120mm ED latest wisdom

[PeterHA]

All,
What is the latest wisdom in regards of the Chinese Skywatcher and similar 120mm f 7.5 ED doublets for VISUAL ASTRONOMY especially planets, double starts and moon?
There is a lot of information about them for AP use but I am only interested in VA and I am not certain how they are for that application.
How do they compare to a premium doublet like the Takahashi TSA-120 or a AP Star12ED (long discontinued but still around).
I have a Swiss AYO alt az mount which will carry easily up to 8 kg.
Cheers,
Peter

[Profiler]

They are generally regarded to be excellent bang for your buck however there are, naturally, some differences with premium brand refractors. For VA it is fantastic however it might be worth also looking at the latest 100mm Tak doublet FC-100DC which is roughly the same price

http://www.astronomy-electronics-centre.com.au/

[PeterHA]

Hi Profiler,
With 100m the Tak should collect quite a bit less light and from experience I think 120mm at f below f9 is managable, so I would go for 120mm to get max resolution and light gathering for a refractor.
Cheers

[Profiler]

I think there is something to be said about quality of optics in the comparatively small refractor sizes. The Tak I mentoned is a 100mm real fluorite crystal doublet whereas the SW is a massed produced fluorite substitute. For VA it might be surprising.

[Satchmo]

A 120mm scope collects 44% more light than a 100mm . Taks are always given mystical properties that they can transcend the laws of physics - they can't .

In these sizes for visual you do not need flourite glass - my Orion 120mm F7.5 Epoch shows absolutely no visual colour . It is not really grab,n,go as you need to move it around in the case which is about 13kg all up.

All that being said 120mm is not enough light gathering for any level of satisfying visual observing , bar a look at the Moon or a bright star cluster . Put and off axis- 120mm hole in front of your 12" dob and see how fast you lose interest !

[Profiler]

Traditional wisdom also suggests that whether the refractor is a doublet v triplet is another important variable for contrast in VA hence why the new Tak is specifically a doublet Fluorite crystal primarily intended as a VA instrument.

Additionally, its design makes it very light, portable, easily mounted/balanced and has a super fast cool down period.

Better quality optics (glass) will allow greater magnifications without breakdown in comparison to lesser quality optics. This issue is not simply relevant to looking at bright objects such as planets but also important for viewing dim objects such as DSO's - The current issue of Oz S&T explains this point in nice simple terms as well.

There is something to be said for the old expression quality over quantity. I have personally seen plenty of examples where a much smaller aperture very high quality refractor beats the clappers out of a much larger aperture but lower quality scope.

[Satchmo]

He already owns a 12" Dob according to his sig, which is why I suggested to use an off axis stop too simulate what he would see through an unobstructed 120mm aperture .

In my experience 8" aperture is where the utility starts for a scope on all different kinds of visual objects. Resolution is obviously far superior with a large well collimated quality optics.

[clive milne]

Never mind 120mm, I lose interest at 18 inches of aperture (unless there is a pair of em)

[MortonH]

I'm curious - wouldn't your 150mm Mak be good for visual observation of the objects you mention? If it's f/10 I'm guessing it might be an Intes Micro, and they're excellent!

[PeterHA]

All,
My Doboson is a Bintel and so the optics are OK but not stellar. I take the beast out if I have a lot of time.
My Mak is the one I contemplate to replace, it is optically great it is a early Intes MK-65 with the helical start diagonal focuser unit, a bit hard to get focus for all my EPs and the cool down period is quite long. Before I got the Mak (1992) I had a Vixen 102mm f10 Achromat and the Intes was a step up in resolution.
Now I am contemplating to get something which cools down faster, is still as portable as the Mak is and shows at least what the Mak showed on Planets and double starts. I observe mostly from my backyard.
Cheers.

[Satchmo]

Peter - A 120mm Refractor would definitely be too large and heavy if you are looking to replace a 6" Mak , and not that much gain from your triplet 100mm APO . Have you considered something like a 6" or 8" SCT OTA ? I've looked through a Celestron 6" OTA and thought it was very good.

[issdaol]

Hi Peter,

The TSA120 is actually a triplet APO not a doublet.

I have had a chance to compare our TSA120 side by side with quite a few scopes at some star parties which had amongst other scopes Skywatchers (one was the Black ED) and Televue and on the same targets there is a difference that you can notice visually.

However you have to remember there is a big difference in price as well so it comes down to if that difference is worth the extra dollars to YOU.

For me personally, when it comes to visual observation then I want the best optical performance combined with best build then I look at the dollars.

For me personally 120mm is the smallest I would go for a APO. If you want quality visuals at a higher diameter reflector design then the Mewlon 250 and 300 is very good.

Hope this helps

Cheers

[Profiler]

Hi Peter

If you are:

1) In a light polluted area

2) Want to use something conveniently in your backyard (which is light polluted)

3) Want something easily portable

4) Want something that cools down superfast

5) Want something that is primarily for VA only

6) Want something primarily for looking at planets and double-stars

I would recommend a good quality doublet refractor. You wouldn't even really need a 120mm refractor. When you want a light-bucket use your Dob

In line with Phils comments the TSA-120 has be considered by a few Tak experts I have met as probably the best refractor Tak has made all variables considered. However, it is expensive and is certainly designed for AP purposes - that is - to go well beyond VA and also be superb for AP purposes as well. If money is not an issue then simply buy a top shelf refractor such as a TSA. However, if you can specify your variables about exactly what you want then you can certainly get something else (i.e. smaller) which will certainly do the job and cost less. For the variables you have mentioned a good quality doublet around 100mm would give you the best bang for your buck and images through the EP.

[PeterHA]

Thanks Phil and Profiler,

That is where these forums shine: making experiance accessible!

Based on what you guys have written, and the very good description of my scenario in Profiler's last message, my path forward takes shape:

If I have time I take my 12" dobo and thats it, especially for nebula, GCs, PNs.

If I have not much time and want to look at planets, double starts and other similar objects I should consider a doublet, on my AYO with DSC this would be a nice VA setup.

I see the following options here:
Skywatcher 120mm f 900 ED, that size/ weight is still OK on both my mounts, is not longer and not much heavier than my old Vixen 102M achromat.

Takahashi FC-100D, that is very light, good optics but only 100mm, would be great if they would make a FS-120

A used Star 12ED which is 120mm f 1020 (I know someone selling one)
Question is: will the Skywatcher or the FC-100 be on par with the 150mm Mak. If taking the central obstruction and difraction effects into account the Mak resembles something like 120-130.
If I get close with any of the above, the faster cooling down and better focuser of a refractor would probably do it for me.

If anyone wonders about the 100mm achromat if have in my signature, this is a kit which was sold 2000 in Germany by BW optics. It's a 3 element Achromat f6 (intended for military Binos) which only works up to 100x and also only because I have 110mm glass path before the focus. Without a glass path anything above 60X looks not good. Great for travel only 400mm long and enough size for some fun on holidays on an alt az mount. This is no planet machine..far away from it.

[MortonH]

Last weekend at Katoomba I had my SV110ED and Skywatcher 150mm Mak (f/12) set up side by side on my dual-scope mount. I had a 22mm Panoptic in the Mak (82x) and a Pentax 10mm in the SV (77x).

In general, I was surprised at how similar the views were. In other words, while the Mak was a bit brighter the contrast in the SV made up for a lot of it. However, I should qualify this by admitting that there was no dew shield on the Mak, which might have improved the contrast.

Steffen had his Intes MK-67 there and it also showed more contrast than the Skywatcher Mak, which was no surprise. I'd assume that your MK65 performs similarly to the MK-67.

So, extrapolating my setup to your question, I might think that a good 120-130mm refractor would perform similarly to your Mak on many objects, and also allow low magnification views that the Mak can't achieve. I think the 100mm would be quite a bit dimmer.

However, the question is how do you define "good" in relation to the quality of your Mak? I've never looked through a 120ED but I imagine the contrast would be a bit below the Tak and AP scopes you mention.

Don't know if this helps or not :shrug:

Good luck!

[Profiler]

I am sorry Peter I can't help with this question other than to concur with you that I likewise wish Tak's new doublet flourite refractor came in a 120mm or larger size.

Suffice to say the discontinued Tak FS-128 has an absolute cult following which might explain why Tak is gradually and somewhat tentatively going back to flourite doublets.

[bigjoe]

JUST MY 2 CENTS I CONCUR WITH MORTON AND SATCHMO I cant understand?, youve got a quite portable excellent mak already! FOR WHAT ITS WORTH .IVE HAD refrs. A 4" UNITRON REFR from astro many moons ago for instance, and though great on planets, dsos where unresolved and dim.for portability ,optics, brightness, resolution , a 6 sct from celestron easily beat a 6' gold sw mak i had also in every facet and it was no slouch! the bd mak may be better, as fresh coatings, schott glass etc as would be a new intes.there seems to be very little to be gained going for a cumbersome refr of that length! anything bigger and it will be unportable
ps: everything needs some time to cool down optically, some longer than others ,theres NO free lunch! cheers

[Wavytone]

Peter, you already have a 150mm f/10 Mak. A smaller refractor will do absolutely nothing of use for you, IMHO, unless you want to use it as a very big finder, or guide scope.

FWIW I have a 102mm ED doublet APO refractor, an Alter M703 (7" f/10) Mak, and a Skywatcher 180mm f/15 Mak.

My refractor does produce a good diffraction pattern with only the barest hint of colour - surprisingly better than I expected, however f/7 is too short to be much good on planets (the combination of f/15, cassegrain optics and longer eyepieces is much better) and for DSO's disappointing except in very very dark skies. Katoomba airstrip is ok for fun, but IMHO its not that dark compared to really good sites.

My refractor doesn't get much use, frankly because the two maks do significantly better on DSO's (aperture), planets (where high agnification resolution counts) yet small enough to be dead easy easy up. When I do take I out, it usually ends up serving asa very big finder 4 degree field) for the f/15 Mak, which once aligned, can stay at medium to high power. An expensive luxury, perhaps.


A 120mm f/7 won't be noticeably better - having looked through a couple.

[Satchmo]

The range of high quality short focal length , long eye relief eyepieces, available today make an F7 ratio telescope perfectly suitable for planetary observation .

[Profiler]

I can't comment on comparisons of one non-descript refractor can supposedly do against another.

However, in my personal experience I have been able to compare a f7 TV-85 against a Vixen 102M which, IMO, was an excellent F/10 achro refractor as well as a Vixen 140 and a host of Skywatcher big achros up to 150mm. On every occasion there was simply no contest, with or without any combination of VR filters etc the TV-85 beat the clappers out of the others in terms of the crisp, clear and detailed image rendered of Saturn (for example).

However, two important variables (both of which Wavy mentions) to keep in mind. First, and most important is LP and thus your location. In a suburban light polluted back-yard I couldn't see any difference in DSOs between a 140/152mm refractor and the TV-85.

Second, quality of eyepiece does make a big difference. You need to be consistent the whole way through with the optical path. Probably the absolute best eyepiece for the 'specific' parameter of light pass/contrast are the Pentax XWs. There are many other excellent eyepieces which are superior on other attributes but for this specific variable in viewing DSOs through a refractor I found the XWs to be best.

[MortonH]

Hadn't considered that so much as the scope itself. Next time I get away from the city I'll need to redo my side-by-side using my 21mm Pentax XL instead of the 22mm Panoptic.

[brian nordstrom]

:shrug: Peter I would put my Istar 127mm f8 achro up against your TV85 on Saturn any day , the Istar would win in every way .
that's my opinion .
As would any 120mm Ed doublet on the market today .
I find the 120mm class refractors to be the best all round scopes , size/performance ratio .:thumbsup: .
Brian.

[Profiler]

Sorry Morton - XLs don't use Lanthanum glass - only the XWs. The XL are akin to the Pans so I wouldn't expect much of a difference between them in light pass/contrast.

[MortonH]

Well your Istar isn't exactly your average achro, is it? :D

But the OP's question is about comparing a 120ED-type scope against his existing 6" Mak. I came across a post on Cloudy Nights the other night where someone did this comparison and said they were about the same in terms of image brightness. But obviously different animals when you consider portability, resolving power, etc.

Then there's the actual optical quality of the scopes being compared. Is a Skywatcher 120ED as "good" as an Intes MK-65? I don't know. :shrug:

Personally I'd like both!

[MortonH]

Thanks. Didn't know that. Must compare the XL and Pan when I get the chance.

[Profiler]

":shrug: Peter I would put my Istar 127mm f8 achro up against your TV85 on Saturn any day , the Istar would win in every way .
that's my opinion ."

This is an example of the problem - I am not speculating/espousing my opinions of what might be but empirically reporting my direct observations of a TV-85 versus the other specified refractors. The Vixen 102M is an absolutely superb f/10 planet killer with 100% Japanese glass - but the TV-85 still beat it providing a superior crisp, clearly resolved image of Saturn.

As far as planetary observing at high magnification is concerned I am doubtful any achro under f/12 will rival a top shelf APO - but rather than affirm a view I will accept the challenge and next time I am in Darwin we can see for ourselves.:thumbsup:

[bigjoe]

Buddy if i can help.Even v good refr. Will NOT break the laws of physic, optics.Legendery status is quite often just a marketing ploy,to suck in the inexperienced and gullible.Slightly sharper image yes but a Properly cooled mak around7" mark would kill it for resolution as would a 9 1/4 sct.just depends what your expectations are.Waste of money in my view!
Now if it where one of the other scopes mentioned.wow! Ill probably end up with a 7/8 mak myself!:)

[PeterHA]

All,

Thanks for all you valuable input.

After this input from a variety of people I have come to the following conclusion:


For now I will keep on going with my Mak, but I will address the shortcomings:

Change the focuser to a Crayford style (lookig for a used one to adapt) as the helical + extension (plug-in not sliding) is a pain
Store the scope dust protected in a location closer to ambient temperatur to get quicker cool down
Long term I will try to direct compare to a 120 ED, one member has offered via PM.
Depending on what this comparison shows I will either be happy with my Mak or hunt for a 120mm ED or try to have a look through a premium 120 APO.

Cheers,

Peter

[Profiler]

Joe - I am specifically talking about a smallish high end APO refractor vs a larger Achro on bright object viewing such as planetary observing at high magnification - I am not commenting on a Mak for DSO etc:)

[Steffen]

I bought my MK-67 a Moonlite CR focuser for its 10th anniversary :P

They have an adapter plate for the MK-65 as well, all you need to find is a 2nd hand CR (Newtonian) focuser.

Cheers
Steffen.

[bigjoe]

Prof.Focusing and cooling are critical withh these maks, scts.Esp maks thats why it appears, quite often that a smallish ed will beat them on planetary.A little bit blobbier
Etc A new focuser os almost a given!
But point taken. For quick views etc you cant beat good 80/ 120ish glass.But my preference is some apperture as other people as well as myself want to actually see resolution on globs and say wow!, and not say" i cant see a thing"?esp now near the zenith in sydney,plenty to see.Cheers.PS: Hope you and all are well and prospering.

[Satchmo]

Profiler - Saturn as an example of comparative performance between Acros and Apos is a classic red herring for an example . Saturn is fairly monochromatic (yellow ) in colour and looked good at high power in my Chinese 6" F8 achro where as Jupiter was bathed in false colour. On Saturn I would certainly expect your 127 Achro to outgun an 85mm Apo....

Re 120 ED quality - my Orion Epoch 120 ED F7.5 shows a perfect star test and no false colour , I doubt a very high end APO will show a significant improvement on that to justify 2 or 3 times the expenditure.

[Profiler]

Hi Joe

Yes - good to hear from you as well and hope you are getting some time under the stars in between the LP. What are you using these days?

[Profiler]

Hopefully this isn't speculation and based on actual observations with top end TVs, APs and Taks.

I think it best to simply conclude that we agree to disagree. I have lost count how many cheap and expensive refractors I have personally compared over the years but if money isn't an issue I know which are, from my actual observatons, better.:)

I just can't comprehend how so many people (including myself) around the world are apparently hoodwinked into wasting money buying high end refractors or how companies such as TV, AP and Tak can possibly stay in business if any of these mass produced Chinese scopes or Achros were anywhere as good.:)

Why would anyone bother spending almost 5k on a TSA-120 if a SW BD120 for approx. 2k was just as good:shrug:

[MortonH]

Probably a good decision to take your time. Please share your thoughts when you compare the two scopes.

[MortonH]

Maybe not quite "just as good", but good enough for most people?

[issdaol]

Unfortunately there are many theoretical opinions or opinions based on speculation. Also different people have different preferences and eyesight. The only sure way is to tell by looking through the scopes and if possible do a side-by-side comparison.

If you are ever near Canberra you are welcome to test drive my TSA-120.

Cheers

[bigjoe]

Hi prof.I use mostly a 10"SCT, 80mm acro and 5" mak at the moment.lovely views of saturn one night with a 5mm nagler and parks in the mak.Sct better than all when its ready.But Ive spent my doe on nice, House, merc,jag etc.So the tak 150 is off the agenda. Id rather finish up with a nice mak Prob should have got the mewlon, bd, or intes instead of going car mad again
Cheers prof and all.:) ps dont do this on a mobile pulled over somewhere.Its very difficult to say the least.Engine turned off! . Of course!!!

[Profiler]

Hi Joe

Good to hear (except for the car issue) and it sounds like you have spent your astronomy money very wisely as the most useful piece of astronomy equipment is your own backyard to look up at night.

Take care my friend:thumbsup:

[Profiler]

A Fiat will get you to work as well as a Ferrari would but I can still understand why someone would want a Ferrari. ;)

If driving simply consisted of going to work and nothing else then there would be no point.

However, if you needed to get somewhere really fast (for example) and ensuring all four wheels stay on the ground as you take a hard turn I know which car would be the better and thus, in reality, there are big differences.

[Wavytone]

And an 8" SCT or 7" f/15 Mak will easily slay the 120mm apo's - all of them - on all scores. Even a close match for weight, and for lower cost.

There's a lot to be said for a 7-8" cassegrain over a refractor of smaller aperture. In many ways it is a shame that Celestron and Meade are being killed by the Chinese clones, and unable to come up with any significant innovation to survive.

[TheFacelessMen]

I can think of at least one score where the APO is ahead .....

What About Mirror Flop :P

[andrew2008]

Hi Peter,

Buy the 120ED. There are lots of very good tools for viewing these days and you need to find what YOU like. If you want quick views on a whim nothing that requires cool down will beat it. Time is in short supply and waiting at least an hour for a scope to cool on most occasions i observed soured it for me. Then there is no stress about lack of contrast and mirror alignment. I had an 8"SCT and 80mm ED set up one night and preferred the 80mm view until the SCT reached equilibrium. But even then the lack of contrast annoyed me. It was quickly sold.

Don't make my mistake and see if you can try the 120 first but don't let people talk you out of it. Many people are extremely happy with them.

[Profiler]

+1 - Precisely

We live in a market/industry driven world. If refractors are trumped by reflectors why does anyone make them anymore?

If the top tier refractors didn't demonstrate any significantly superior features in comparison to the mass produced Synta refractors why do companies such as Tak, TV and AP continue to exist let alone why anyone would buy them at triple or more the money?

[Profiler]

+1 Yep

These are all the points I made in an earlier post when I listed variables 1-5

[Steffen]

An implementation detail. There are Cassegrain designs with fixed mirrors (like the one I've got, or Peter's MK-65). The ones with moving mirrors can be retro-fitted with Crayford or R&P focusers.

Cheers
Steffen.

[Steffen]

Maybe for the same reason jewellery is made (and bought), even though it has no practical utility. People like to show off, those things are status symbols.

Now, with refractors that's clearly not the whole story, because they do perform nicely. The question is, can one justify to spend an extra 100% in order to reap a 5% benefit? And if so, its that because the extra 5% are absolutely necessary for one's application of the scope, or is it more like wearing a diamond bracelet?

Cheers
Steffen.

[brian nordstrom]

:rofl: Because of us millions of un-treatable , "Refractor-holics" out here .
HI , my name is , Brian , and I am a refractor-holic ........

One more thing , refractors look like REAL telescopes ;). especially our 120-150mm f7.5 -f10 babies .
Don't they ? :help: .
Brian.

[Profiler]

Or maybe the difference is even more than a tiny 5% but you have to take the plunge into the big $$ first to appreciate this point

[alocky]

Those f10 things look ridiculously short.
It doesn't look real until it's f15.;)
cheers,
Andrew.

[brian nordstrom]

:lol: How about a compromise Andrew , how's about f13?
Brian.

[Steffen]

There is no doubt that big, slow refractors have a certain allure to them. How about this 680mm f/30?

:thumbsup:

[bigjoe]

I like steffens jewellery analogy the best.I myself find it impossible to deny myself opportunity of showing off in a "fancy car".Some people also would like to re iterate or imply the fact that they would only use tak,tv or similar, and all else is beneath them. I think this can be
seen as just another common human failling.Is it just a pathetic and desperate need for attention that most of us possess.Who knows.
Ps:While this is gettin a bit phallic.Has anyone looked at a pic of the big Alvin Clark lately?
Oh I forgot.Its only an achro! Waste of time looking through it in my view. haw ;)

[Profiler]

That is indeed one impressive looking piece of artillery:eyepop:

A telescope and anti-aircraft weapon all in one

[LewisM]

The allure of refractors is irresistable. I have tried EVERY permutation and combination and flavour of telescope over the years, learned to HATE some, tolerate others, but I ALWAYS came back to refractors. I had aperture fever, I lost it again, thankfully! Aperture-schmaperture.

I cannot rave highly enough about my Vixen FL102S refractor, a scope sadly discontinued some time ago. It is a superlative instrument, with incredible contrast and clarity. It is the ONLY telescope out of MANY I have kept, and plan on keeping, including having owned Takahashi and others.

People told me I really shouldn't image DSO's through it at f/9... I proved them wrong. I also image with the dedicated focal reducer at f/6.4.

It is now THE only scope I own, but should have another refractor for travelling etc next week.

I had a few Skywatcher ED refractors - good bang for the buck. Not a fan of ED glass, but that is a personal thing, being a pure devotee of fluorite.

[bigjoe]

Point taken Matt. Refractors are gorgeous just to look at, especially antique ones Ive got one myself!. Not my intention to put anyones noses out of joint here. Just an attempt at levity.nothing more.We all have to poke fun at ourselves once in a while myself
included!cheers buddy.:):shrug:

[LewisM]

I can guess Jenny was not home when you took that photo on the table Matt :)

[LewisM]

I managed to accidentally spray paint (should I say airborne aerosol particles better) the wife's leather shoes with epoxy white paint. Normal paint would have dried in the air before contacting the shoes (I did it in the driveway, and they floated inside the garage), but epoxy having such a long cure time does not.

I got it off with ballistol oil, but I was called all manner of derogatory names for the better part of an hour.

It was fascinating to see just how much DID get a misting of it! Goes to show...

[alocky]

Put a decent dewshield and guidescope on it and I might agree :whistle:

[Profiler]

Although I fully appreciate that the hobby of astronomy is a broad church and has a following catering to many different tastes I, for one at least, have never been interested in the "appearances" of the equipment (other than to assess condition when purchasing 2nd hand). For me a 'telescope' is something I look through to see the universe - not something I look at.

In this context my own experience has always been that the images always tend to be better with the more expensive refractors. I loved my first short-tube C-80 but when I purchased a Tak FS-60 it simply outperformed the C-80 and the same trend continued thereafter with gradually larger and larger refractors. Ultimately, the single most important rule of thumb with refractors based upon actually looking through them was that quality trumps quantity. There really wasn't any emotion to these experiences other than what can be seen in the eyepiece and not what is seen when looking at the telescope.

[MortonH]

A Saxon 120ED has just been listed for sale. Temptation for the OP???

[LewisM]

THAT is BEAUTIFUL!

[LewisM]

Simplicity is BIG bonus IMHO for refractors - nary have to worry about collimation, cool down time is pretty fast, usually pretty manageable and light, and generally don't need a gigantic mount to swing one around the sky.

That Saxon 120 in the trader is a FANTASTIC buy for someone!!! Same quality as the Skywatcher, at an incredible price! Wouldn't mind it myself, but I won't.

[Profiler]

Wow - we have come almost full circle from post number 2!:D

[LewisM]

Good points Richard. I must say the differences in viewing with my FL102S vs the SW ED100 I had was remarkable (an even WIDER gap betwixt the FL102S and the NG120 I had). QUALITY will always trump QUANTITY, but there is also horses for courses... and that is NOT being a scope snob!

I have looked through a couple SW/Saxon 120's, and they are GOOD. I would not rate them incredible, but the extra aperture does not equate to a better image, as evidenced comparing them to 18mm less with the 102 (and 19mm in a TV 101).

I will disagree a little though, and that to ME at least (and several refactorians I know), external cosmetics ARE important. Makes the experience more pleasureable, in an almost intangible way.I like my stuff to look good and perform well, and to the point of less functionality, dislike things like velcro, zipties, etc on my mounts and telescopes. I will also repaint to match or repair. It's the Virgo in me :)

I know a couple here are the same way inclined too :)

[Profiler]

Hi Lewis

You are quite right and I certainly understand some folks also like the looks of refractors - this is what I meant by the broad church with different tastes comment.

I am, personally, not entirely in that camp although, of course, I do prefer any telescope in good well kept condition as opposed to one that has been a dogs breakfast.

The thrust of my point is simply 'why' we do have expensive top tier refractors is more than simply their cosmetic appearance - they do perform as well otherwise we would all have Skywatcher ED120s and there would be no FL102S anymore:)

[alocky]

That's what I love about this hobby - everyone has a slightly different angle on it. Personally, I love looking at my old Unitrons, which is why my house is decorated with them. Rarely though, do they get outside, except for lunar and solar duties. I have other scopes for looking through, because even the 8"f7 newt I knocked together as a kid in the 80s still wallops even a good 5" APO for any observing I do, and isn't much harder to live with.
But it's entirely up to the OP - for the double stars and planetary grab & go visual the new 120mm ED scopes are going to perform as well as any 5". True connoisseurs will, no doubt, easily pick the difference in contrast and aberration control between a SW and a tak 120, but I rarely want to spend the time trying to see it. There's stuff to look at up there! Then again, some people would rather spend their time star-testing telescopes than observing - but that's how they enjoy the hobby!
cheers,
Andrew.
cheers,
Andrew

[Satchmo]

Perhaps you just enjoy the freedom from the possibilities that larger aperture offer ?

In my experience out in the field the refractor lovers seem to be satisfied with fairly dim views of fairly bright objects with no descent image scale and don't look at anything much beyond that - but they are passionate about the 'quality' of what little they see.

I like to see most globulars for instance resolved into a blaze of stars - my 120ED resolves only a handful due to poor light gathering power - though it is sharp as a `Tak' - it sits in its box most of the time.

I've been observing 40 years now and I really don't get it with the refractor thing- honestly . I want to see faint stars , I want copious detail on planets , star knots and dust lanes in galaxies etc - and for me that doesn't hint below 8" aperture .....Perhaps someone can enlighten me ? :shrug:

[LewisM]

Just a personal preference Mark. I am NOT a fan of diffraction spikes at all, so imagery especially for me through a refractor does it for me. I do not like introducing unnatural artifacts into an image.

Visually, well, I just love the contrast afforded by a GOOD refractor. Sure, I may not see as much detail, and I do not delude myself that I can, but I just prefer it.

[Larryp]

Ditto, Lewis:)

[MortonH]

I reckon if it was practical for me to own a large scope and use it regularly I may feel the same. But for various reasons at the moment I can't own a large scope. Maybe I'm under some sort of self-delusion so I don't feel bad about what I can't have!

[alocky]

I must say I've yet to find anything that looks better in a smaller scope. My 25 takes less time to set up than my old starfinder 10". And collimation really isn't the big deal people make it out to be. Hell - it only takes me seconds to set it up - 10 in fact. Here's proof :)
http://www.youtube.com/watch?v=Qf7K9Z8dGGk&feature=youtu.be

[sn1987a]

Happiness is seeing the veil nebula for the first time!.:thumbsup:

[TheFacelessMen]

The original quote was a poorly considered blanket statement that is clearly not 100% correct.

It's still a shortfall in the design which can be extremely annoying. I have owned 3 SCT in the past so I know from firsthand experience. Also you need to spend more money than just retro fitted Crayford or R&P focusers because many need mirror locks as well.

Also the fixed mirror systems you mention are not referring to the usual traditional lower cost Meade and Celestron SCT's but generally more expensive heavier, Cassegrains and Maks so again the blanket statement is very misleading.

[Profiler]

That's easy to answer - you need to actually buy a top shelf refractor such as an AP130GT (for example) and spend a decent amount of time actually using one rather than repeatedly telling and thus convincing yourself that your ED120 is just as good.

As I keep on saying over and over and over again. If the top tier refractors werent significantly better then companies like Televue, Astro Physics, Takahashi, APM etc etc would be out of business decades ago and we would all be using Synta tech ED120s:)

[LewisM]

Just came in from an aborted refractor imaging session. Cloud limited choices to west only, and that was not where I wanted to image, so visual I went.

I had a great time with the FL102S and a GOOD selection of top notch eyepieces. NGC4755 was easily resolved into the colours expected, and I had no difficulty seeing even the dim stars. I then went to a-Crux, and again, resolved it easily.

Slew to M83, and even in this light pollution abhorrence, I was able to happily make out the core and some arm detail. No issue at all.

The only other scope I have used that pleased me almost as much visually was a 180mm Maksutov.

[bigjoe]

Bizzarely.Most people on the cloudy night reviews say and admit their taks are beaten by 8" dobs 9 1/4 sct etc on planets when seeing permits.Its just more to do with pinpoint stars, that crisper refractor view id guess.Most nights rarely allow over 1" arc seeing anyway so the tak 128 will strut its stuff and look fabulous doing it(not a tin can).cheers
Ps:I suppose a lot also comes down to what else you do with your lifemoneywise etc.

[Camelopardalis]

No design is perfect, otherwise everyone would use the same superior type of scope and we wouldn't be having this debate...

Mass market scopes are now starting to include some of these features in the design - Celestron's Edge HD scopes have mirror locks and the newer Meades have built in zero shift focus. They're not inexpensive...here...but the Edge HD stuff is becoming fairly popular in the US with good reviews and promotional pricing. It's just they're expensive here :mad2: But it's not like additional rear mounted focusers don't exist.

[Profiler]

Hi Joe

I know this is the age old debate of reflectors v refractors which isn't what I was actually talking about at this point but rather the differences amongst the quality of refractors - not the competing merits with reflectors. The real problem is that there are too many competing variables to make valid comparisons and hence these endless debates/discussions.

For example, I acknowledge a 12' SCT will beat a 100mm refractor on DSOs. However, from personal experience the folks with a 100mm refractor will be out under the stars 4-5 times more often (all factors taken into account) in comparison to the folks with the SCT due to the set-up/portability/cool down issues. So how do were equate these totally different merits when the old expression is the best telescope is the one you use the most.:shrug:

Moreover, given that a huge part of astronomy is the idiosyncratic variable of atomsphere suggests that the person who is out the most on different occasions is going to have better opportunities for better views and in a quantitative framework will simply see more. Likewise, the person who gets out the most is also likely to get out to different locations such as dark sites. I am happy to accept any challengers who believe their dob is more portable than my TV-85 - body builders and weight lifters with dobs are excluded from this contest:lol:

[Kunama]

Great video clip Andrew, what I really love about the 25" dob is the portability of it all. . . . . ;)

Seems people are forgetting the old "Horses for Courses"
what surprises me and saddens me is the number of people on here and other fora who admit to not being able to find enjoyment in anything but a lightbucket. :sadeyes:

Some have even admitted they would not partake in astronomy if they only had access to a small/medium refractor to work with. :shrug:

Personally I find it an enjoyable challenge to locate faint objects with a small scope like a 120mm F7.5 it is never going to reveal the Veil to naked eye, but what it does within its design parameters is immensely enjoyable to me nonetheless. :astron:

[LewisM]

Agreed 110% Matt. Last night's viewing, for all but the briefest of time, was breath-taking, even in my light polluted suburbia. Absolute pinprick's of stars, with a dearth of colours.

From plonking the mount down to full 3 star alignment then off to perfect GOTOS - 8 minutes. Break down at the end of the night - 2 minutes maximum, including carrying it back into the storage room. And that's just with my own hands.

I personally find telescopes with ANY central obstruction annoying. I have VERY light sensitive eyes, and I can easily detect the shadow of the central obstruction and it really bugs me.

There is something intangible about a GOOD quality refractor that is hard to beat or ignore. If I want to see the whispy details, I'll attach the CCD and do images of it - sure, it'll take MORE subs than a light bucket, but I will get there in the end and without artificial design induced artifacts.

[Satchmo]

My point is that the price point of refractors can lead to a stunting of growth in your horizons as an amateur astronomer. My 120ED is about 13kg in its case - similar to a 10" F5 Newt and a 10" is a far far more useful machine for astronomy than a 5" scope ( I hang on to mine with the idea of imaging one day ) . Theres definately a grab n'go zone for refractors and I can understand some people wanting to stay there !

I have no problem with those that stay in small aperture land all their lives- I do have a problem with people who claim their scopes defy the laws of physics.

[Satchmo]

Lewis - central obstruction shadow or vignetting occurs when the image of the central obstruction in the exit pupil is actually hardly smaller than your eye pupil. If you have noticed this then you must have used low magnifications giving an exit pupil much larger than your eyes' opening and your eye is just not opening up nearly as much as you think either due to ambient light levels and or age. This is not a fault of the telescope - you need to calculate the exit pupil and judge whether you are likely to lose light - is my eye going to be 8mm pupil in this lit urban enviroment or more likely 3mm ? Perhaps I should use a higher magnification.....

[bigjoe]

Hi prof, kunama, all.Yes i did exactly that last night on saturn,and enjoyed the view more in the smaller mak than10 sct.Sure there was more resolution in ths sct but the lovely steady crisper image in the mak was visually more pleasing.So go figure!I think we can also confuse resolution with actual sharpness and clarity of image.More bands were seen in the sct BUT the mak served up the more pleasing image hmmm v interesting.Even tuc47 looked good in a nagler with only partial resolution.So there you are then.Or is some of it also the thrill of hunting down faint stuff in smaller apertures also?

[Kunama]

Mark I agree with what you're saying and I think anyone planning on owning only a single scope with a view to it giving them a satisfying visual experience should look at the 8"-10" reflector as an allrounder. Personally, as I previously discussed with you, my future plans (after I finish the 2 80mm F15 refractors currently being built) include the building of a "Photon Hog" to complement my current 120mm scope, something from 12.5" to 18" range.

Yes there are always going to be claims of small scopes bending the laws of physics, personally I have had enough time with 80mm to 150mm refractors to know where their limits are for VISUAL. Within those limits and expectations these scopes are very enjoyable.

I agree it would be a shame for someone to never venture into the territory of the 12" and larger scopes, even if only borrowed views at starparties.

BUT we digress, the OP asked whether the difference between an ED120 and a top shelf APO 120 was sufficient to warrant the extra $$$$. For me, yes but is it necessary to spend that amount for visual, NO.

[issdaol]

:confuse3:

Not sure what you mean or validity of this statement. I don't see how the price point of refractors can stunt anyone's growth as an astronomer provided they can afford it and use it to best advantage.



I don't think anyone is claiming that their scopes defy the laws of physics. But there is more to scopes and image quality than just how Big the Aperture/Mirror is. A crappy 20 inch mirror will most probably be worse than a 5 inch APO. Similarly a excellent 20 inch mirror scope that is poorly mounted and aligned in a poorly designed tube/truss will require a lot of effort and maintenance to use.

Also not everyone has small trucks, trailers or wagons to cart around some of the massive "so called cheap" dobsonians

The other thing that I find interesting is the armchair critics that provide seemingly expert comments/advice on scopes that they have never owned or used. ( Not to mention the scope owners that love to try and say that Tak, TV, TEC or AP owners were ripped off or stupid for having paid more than their cheaper Chinese scopes ).

The point is many people have different uses, preferences, budgets etc so their choices may be different for different reasons.

[MortonH]

My experience at Katoomba last week may be what Mark's getting at.

I spent most of the evening happily fiddling with my new mount and the two scopes I had on it - a 110mm ED refractor and a 6" Mak (also new). About 10 metres away were a couple of guys with a decent-sized Dob, I'm guessing around 14"-16". While I was content to find stuff I hadn't seen before, thanks to the Sky Commander on the mount, I was aware that while I was looking at grey "smudges", the other guys were describing glorious spiral arms and other sights that are beyond the reach of small scopes.

I don't feel stunted because I still have a lot to see with my current scopes, but I am certainly aware of their limitations in the detail they can show. And so the next time I get the chance I plan to spend a bit of time away from my own scopes and pester the owners of the big Dobs for a proper look through them. :D

And as for price point, it is interesting to think what kind of medium-large Dob I could get for the money I've spent on all my "small" gear...

[Satchmo]

Thats simple Phil - if you believe that you must own just high -end refractors you are probably never going to own anything bigger than a 6" refractor and that is going to really narrow the horizons of what you can see. ( And I have indeed been looking through all kinds of telescopes including Tak refractors for 40 years. )

I am not arguing retractors against massive reflectors in this thread - I'm saying that a good 8" to 10" scope is where the field of what you can see and how many objects blows right open and your 4" APO regardless of how much you pay for it is not going to come close in overall usefullness . Phil , I notice you have a 12" Tak Mewlon as one of your two telescopes so you are not limited to 120mm aperture ...

And other designs can do very well, in low contrast resolution of planetary detail . We once had a shoot out betwen a 10" Newtonian and an Astrophysics 7" F9 Starfire refractor under very steady skies and everyone agreed even on Jupiter the view in the 10" won hand down. W must remember that smaller scopes just cannot resolve the seeing which is usally diffraction limited at 4 to 6" aperture - any larger scope unless the seeing is really good will give the perception of a loss of sharpness earlier than one that breaks down a view into airy discs at a similar magnification in X per inch. So the smaller aperture scope has the `sales' advantage of superficially sharper images , becasue it is not capable of resolving the turbulence in the atmosphere.

Anyway I'm not sure what conclusions about improvment of a Tak vs cheaper 120ED which was the subject of the thread. My comment is that if your refractor returns a good star test and is colour free then it is going to be near perfect at the focal plane no matter how much or how little you pay for it . I would maintain as an experienced optician that a lot of the fervent chatter about Taks is due to good quality control which you pay for . Any telescope with freedom from spherical aberration and astigmatism with well polished smooth surfaces will perform brilliantly at the eyepeice- its a zing you can get with any good scope - that feeling that there is nothing in between your eye and the object you are looking at .

[brian nordstrom]

;) Refractors , gotta love them .
87 posts and still going strong .
:P. Reflecting on this ...

Brian.

[brian nordstrom]

:shrug: against physics , my Tak sky90 f5.5 and SW 102 f5 , both 500mm f/l's , the Tak shows more on luna, planetary and deep space than the sky watcher? .
Don't give me the "Coatings" thingy , ok , the SW coatings are new generation . The SKY90's are 10 years old , technology wise ? don't think so ..
Please explain ..
( See my post in Celestial events chapter titled this , spotted something this morning ....) ..

In my opinion a 120mm SW using an fl53 doublet APO is the bees knees , grab one and enjoy . Gonna be a classic like the ED80 .

Brian

[alocky]

If there's such a thing as a usable, cheap massive Dobsonian I've never come across it. And for what it's worth I also own a Tak, as well as a pretty respectable stable of Unitrons, Meades, Celestrons and a few quality home brew optics. Despite this, I have friends; so add in Astrophysics, TMB, Zeiss, Questar, Zambuto and even the obscure Suching :) to the list of products I've been able to assess objectively over time. Resolution and visual limiting magnitude are a function of aperture. End of story. Get over it. Contrast is pretty much a function of good instrument design and maintenence.

I spent the money on the Tak to get the flat field and good aberration control for photography with a full-frame DSLR. In the world of astrophotography there are plenty of great images online taken with 'lesser' scopes, although once you've stumped up for the upgraded focuser and field flattener you may have been better off with the Tak...
For visual use, which is what this thread is all about, the eye is far more tolerant of field curvature and chromatic aberration than a sensor, and I would imagine that there are few people more qualified than a master optician who owns an ED120 to comment on whether it's as good visually as a reflector of equivalent cost.
I've heard plenty of Tak and AP owners claim that their scope regularly outperforms a scope of twice the aperture, but have yet to see it for myself. And to returen to the topic of this thread, my APO Tak is no better than either of my 30 year old achromatic Unitrons visually, but I love the digital images it produces, and there is no way I could take them through an f15 Unitron.
Cheers!
Andrew.

[brian nordstrom]

:thumbsup: Hear you Brother , the flat field problem in both my fraks , is not there , The 120 SW's good reviews impresses me every time , its gotta be very good .
as good as my now sold ED80 that had none as well . Nice optics .
So it aint flat field ? :D. Buy a Panopotic,by TelVue .
Its Refractors , like a Synta 120mm f/8 APO doublet .
That allow us hard working astronomers the chance to own , use and enjoy a top notch Refractor .
Brian.

[Satchmo]

Brian , the Tak Sky90 is a Flourite Doublet and the SW 102mm F5 is just an achromat ... I would call that a significant `physical' advantage ;)

[brian nordstrom]

:shrug::shrug: Photon thru fare , sthell ratio ? 50 year old eyes , 20 year old eyes ?? , my Takahashi SKY90 shows more than my 102mm f5 Sky watcher , Physics ? man ..
Brian.
Brian ,

[Profiler]

As an aside I don't think referencing the Sky90 is probably the best case example. Although it certainly has some avid fans it is probably one of the few Taks ever made that has attracted criticisms as a poor design. The market concept by Tak was to make something to compete and capitalise on the legendary market niche of the AP Traveller. Some think Tak acheived this but others have criticised its degree of colour in pushing the envelope with short fl to be off-set by the genuine fluorite crystal.

However, once again I want to reiterate that it does have some strong supporters/advocates but I wouldn't regarded it as the best design from the Takahashi corporation.

[Profiler]

With respect to objective coatings there are clear differences in the brands epecially with respect to their durability to such things as sky gunk requiring cleaning, moisture damage/erosion and general longevity.

Ironically, the best example I have personally been able to observe of this point in the short term was with two diagonals (a GSO and TV Everbrite) I purchased at roughly the same time.

Initially, I was immensely, immensely impressed with the GSO providing great performance for an absolutely magic price and disappointed with the Everbrite being super expensive and not really any different to the GSO.

To-day, now roughly three years later however I can see deterioration of the coatings creeping in all around the edges of the GSO mirror - the Everbrite is exactly the same so rather than puffs of smoke and bravado I can accept the TV marketing as not merely hyperbole and their products in the context of life time investment etc.

[LewisM]

I hate to say it, but the only Tak I ever owned - an FS60 - I disliked immensely. The CA on even medium mag stars was REALLY noticeable, let alone on planets. I was very disappointed, though Tak never claimed it to be super corrected (I found it WORSE than a SW achromat I once had). Beautifully made, superb focus (once I got enough damned doodads and adapters to get it to focus!), but the CA spooked me big time. I found the finder better corrected :)

I note NO CA in my FL102S. Nada, zilch, zip. And that's just a high performance fluorite doublet! And it performs beautifully photographically, no doubt because of it's remarkable Strehl ratio.

I have plans for a WO Megrez... be interesting comparisons...

[bigjoe]

Prof hi.If thats true then it could apply to all clones etc when ot comes to longevity o f coatings.Could it be just possible that the Gso which I also have coulld have been used more often and thus exposed to the elements more often and thus cleaned more often etc.leading to loss of coatings.Otherwise Im keeping my fingers crossed with mine

[alocky]

Actually Lewis, it performs well because of its relatively slow f-ratio. Strehl is usually an on-axis measure, and the faster the scope the harder it is to keep under control as you move off axis. That's why the FSQ has 4 elements, and most of the 3 element APOs are a lot faster. Before fluorite glass was available, a flint and crown doublet around 100mm had to be f15 or thereabouts to produce an acceptable fov. That's how vixen killed Unitron!
Cheers,
Andrew.

[Profiler]

I thought about that as a possibility - also - I may have simply been unlucky and got a bad one off the line but usage would be reasonably even overall or if anything more towards the Everbrite. Initially, I used the GSO until I purchased the Everbrite and then I used it instead of the GSO. Either way a bad diagonal isn't a big issue but I think it does highlight issues with coatings and I certainly wouldn't be so blase' with similar problems in objective coatings

[LewisM]

Thanks for that! :hi:

[Richard Gamble]

Why compare apples to oranges?
You certainly do not need to spend 6 grands to enjoy the night sky.
Infact, a humble pair of binos and a good pair of eyes is all you need!

[Kunama]

Totally agree but I can also understand why some people want to take it up a notch or two, it has nought to do with showing off. Whether imaging or visual is ones goal, if we were all content to view the heavens through a pair of binoculars there would be a lot of opticians, telescope manufacturers, accessories makers etc out of work.

I think its great that amateurs like us are able to access equipment of the caliber of Astro Physics, Takahashi, Obsession and SDM for a very reasonable price (compared to owning such equipment a few decades ago, when a good scope cost as much as a family home)

If we all settled on a mediocre scope without critical reviews and opinions on forums like this, then that is all the makers would give us.

Having said that I would not think any less of someone who chose to spend less and were content with what they got for their $$$. There are certainly premiums paid for certain logos. A $6000 Tak is not going to be 4 times as good as a $1500 William Optics, nobody expects it to be.

[Profiler]

+1

Indeed I suspect the ED120 will outperform most bino's on planets - even 2-4k bino's

[Profiler]

I have to admit looking back at this thread - whatever peoples different views may be between reflectors v refractors one thing is certainly clear - 'Refractors' whatever their size or quality certainly do engender passions amongst AA's:rofl:

[Profiler]

Not sure I am following this post. My experience with the issue of coatings more pertains to their longevity and resistance to potential harm. In this context I don't believe there is any contest between the applied coatings in premium brands compared to the budget brands. I have come across plenty of Synta Tech equipment wherein the coatings show signs of natural decay (i.e. not damage from misuse etc). Your 10 year old Sky90 is a tribute to the quality standards of Tak equipment and why it is still going strong even today.

Issues of optical performance more relate to the optical lens design, quality of glass and quality of construction/correction etc Thats my 2 cents worth at least:)

To put this all into perpsective with a hypothetical - hands up anyone who honestly thinks one of the mass produced particle board 10' Synta tech Dobs will still be in one piece if purchased today and used reasonably regularly over such a time period?:D

[alocky]

This is a very good point - I have friends who own and use 'good' quality fork mounted SCTs and have had them for a few years, with no issues. On the other hand, exactly the same scope subjected to the level of use of regular public outreach sessions at Perth observatory has not fared as well, with drives wearing out surprisingly quickly. Horses for courses! Meanwhile, the 100 year old Calver does its thing without any fuss night after night, and in the main dome, the Boller and Chivens has been going about its business for many decades, every clear night. I think this level of quality is another step in cost beyond AP, Tak etc...
regards,
Andrew.

[bigjoe]

In some countries there seems to be a few 30 yr old temma tak mounts still going strong with only maybe the bearings changed (not a hard job),the gearings being made of silicon bronze.So very tuff, even when a lot of them have been overloaded with C11s and all the astro gear. Thats just one of the reasons these mounts are so coveted.Cheers

[Satchmo]

Depends if you are after an heirloom to pass down or not - I'd rather a larger dob with a tired looking mount in 10 years thats actually shown me some serious stuff than a pristine refractor that has not , but will be a nice heirlom for a family member when you are gone.

If you are looking for longevity then you get what you pay for. Most of the SCT's around today will end up in garage sales because their electronics can't be maintained rather than mechanical failure.

[LewisM]

In the past decade, I have owned and resold a lot of scopes; refractors and reflectors (Maks, Cats, Dob Newts, Newt astrographs).

Out of all that mess, I kept 2 scopes - both refractors.

All depends what you want to get out of it and your own precepts. Refractors fit my needs and tick all the right boxes in my lists.

[Profiler]

Yes - but the hypothetical was who honestly thinks a 10 year old Synta tech dob will be in one piece with a functional mirror with coatings etc

[LewisM]

I was surprised that my crappy Bushnell 8" Dob lasted 10 years - and it was cheaper than any Skywatcher. But, it did, with absolutely minimal damage. I resold it here, and it is still going strong.

Though, I have to admit, it was that exact scope that put me off Dobsonians for life. Utterly frustrating! I will say though, it held collimation INCREDIBLY well!

[Satchmo]

The 3.9m telescope at Coonabarabran has to get a new coat every six months :)

Recoats are just basic maintenence- kind of the tax you pay for getting all that light so cheaply! We have allready seen in other recent threads that an 8" refractor free of false colour ( as a reflector is ) can cost around $250,000 .....You would not expect to run your car for 10 years without changing the oil regularly.

That being said , to my knowledge 98% of all the mirrors I have made with a basic quartz overcoat are still in service with their original coatings many which are coming up to 15 years old.

[David Niven]

You will see more per dollar with a dob than with an over prized refractor.
Sharp flourite lens are useless, without sufficient light !
This is especially true for visual DSO imho.

[Steffen]

Probably not a lot of people. But it doesn't really matter, the 10" SkyWatcher Dob costs $800. You could buy a new one every three years and still be ahead (by a large margin).

Cheers
Steffen.

[Profiler]

Its interesting that few can actually answer the hypothetical and instead have to re-characterise and alter the posed issue.

The hypothetical isn't whether recoating of a mirror should be viewed as a routine maintenance issue, it isn't whether you can purchase several new dobs at separate time intervals for the same or less money and it isn't about the perceived visual capabilities of a dob v refractor.

The hypothetical is who honestly thinks after 10 years a Synta Tech dob would still be in one piece and operating fine. This point is made in contrast to Brians Tak Sky90 which is 10+ years old and essentially in the same optimal condition.

Given that no one really seems able to answer this without resorting to conflating the posed issue I think my point is made

[Steffen]

I thought I answered it, not many people would believe that a particle board Dob would last 10 years with frequent use, dewy conditions etc.

What isn't clear to me is the point you consider made. That expensive equipment is expected to last longer? Wouldn't that be a default assumption?

Cheers
Steffen.

[LewisM]

Richard,

As I intimated above, I partially agree, but mileage varies.

My FL102S is around 20 years old, PROBABLY. In pristine optical condition. Can't ask for a better scope in MY opinion.

The Bushnell 8" Dobsonian I had was subjected to some sordid conditions, including living in red dust at a friend's place for 3 years whilst we moved away for work. It survives to this day in pretty much the condition I bought it in, and, after I cleaned the red dust off the primary, there was only 1 TINY coating deterioration spot. I call that pretty respectable for a cheap scope.

I personally have aversion to ANYTHING astronomical being made from either plastic, cardboard or particle board (let alone god forsaken MDF!), but that is a personal subjective objection only

[Profiler]

Yes - you do concede the point that Synta Tech equipment doesn't last:thumbsup:

With respect to the automatic expectation that higher quality more expensive equipment will last longer - well - wouldn't the analogous logic to that assumption extend to the earlier point about the optical performance of high quality refractors aren't going to be the same as Synta Tech refractors:P

Otherwise - as I keep on stating ad nauseum - if a Synta Tech ED120 was the same or even close to a TV-NP127 (for example) then companies like Tak, AP, TV, APM etc would have been out of business decades ago and we would all be using ED120s

[Profiler]

Hi Lewis

I missed your previous post - okay - point noted but then I find it very poignant that you conclude that it also put you off Dobs forever:rofl:

[Steffen]

It does last, just not as long ;) I have a GSO Dob that is about 3 years old and shows no signs of ageing yet. So yes, you do get some use out of them.



Not at all, being shorter lived doesn't mean that their optical performance can't be excellent when new. Talking about Dobs here, see below...



To be honest, I don't understand what the attraction of those 120EDs is, but then, I'm not an imager. I wouldn't touch them with a ten foot pole, given how much more useful scopes you can get for that sort of money…

The complication of this thread is that we've been arguing over three corners – expensive frac (high quality, limited usefulness) vs SW frac (to me as useful as tits on a bull) vs Dob (very useful, not lasting forever but cheap).

Cheers
Steffen.

[Profiler]

You make some good points Steffan and this is certainly a somewhat diverse thread.:)

[LewisM]

Indeed it has. I have looked through behemoth cannons (Obsessions etc), and whilst the views were enjoyable, it wasn't my cup of tea at all. I know others thoroughly enjoy them, but alas, not this little duck.

It's all about what YOU want to get out of it. I intend that my FL102S will out last me, and probably even my Williams Optics Megrez. Longevity surely plays an integral part in my decisions about equipment, but is not the sole factor.

I have had Synta/Skywatcher/Saxon's, and none "grabbed me", even their mounts. While of acceptable quality, not one of them was a keeper.

To each their own.

[LewisM]

This is the only point I would disagree on.

Limited usefulness for a quality refractor... I vehemontly disagree there. If I want to see the faint and whispy, I'll image it (and not have diffraction artifacts). If I want to have exceptional views of the Moon and Planets, I will just drop in an eyepiece. I find viewing DSO's in all but the most behemoth of reflectors absolutely useless anyway.

As I have mentioned before, the ONLY reflector I miss is my 180mm Maksutov - a good scope, but not without it's drawbacks too (image shift, average quality of construction, LONG cool down etc).

[MortonH]

Hey Steffen,

You left your 6" Mak out of the equation! And by some of the comments even this might be considered near "useless" for deep sky observing by some people. :P

Maybe we forget that some observers, myself included, have done a lot less visual astronomy than many people on this forum. Sometimes simply tracking down an "easy" object in a small scope can be rewarding. I haven't even ticked off all the Messier objects yet, so I am easily thrilled by seeing an object for the first time with my Stellarvue 110ED, even if it shows little detail.

Maybe one day I'll have seen so much that nothing less than a 20" scope will excite me... :question:

[Kunama]

That would be a very sad day indeed! I fear some people have already reached that point ..... a shame indeed :shrug:

[clive milne]

This thread has as much win as Edsel future options in 58.

[el_draco]

Not likely. I owned a 29" newt for a few years yet I still get high (haha) using a pair of binoculars.

Despite the physics, size is not always an issue in astronomy... it just offers a few different opportunities for pleasure...:eyepop::eyepop:

[Steffen]

Pure self-restraint :P I try to keep myself from bringing it up at every opportunity :D Seriously though, back in 1999 it was the biggest I could afford and it's still as small as I would go (or recommend to anyone else). Its contrast advantage makes it roughly as useful as an 8" Dob for DSOs under ordinary skies (which is what I mostly have).

The Intes MK-67 is history now, but its Intes-Micro descendants go for less than a 120ED. No contest as far as I'm concerned, unless you need a fast scope for imaging.



I don't think I'll ever stop loving the Intes Mak (unless a Mewlon miraculously shows up at my doorstep :lol: ). However, I'm fairly certain that there will be a 12"-16" Dob in my not too far future as well.

Cheers
Steffen.

[Profiler]

+1

Yes - I think that is a very astute way of evaluating things

[Satchmo]

I've used scopes up to 36" but I think the sweetspots all factors considered sit at 4 or 5 " refractors for wide field and 10" and 16" reflectors for Deep Sky and Planetary .

Tha being said I enjoy the naked eye views from a dark sky now more than ever !