New telescope advice

[schmourghenne]

Hello everyone,

I used to have a friend that would would introduce himself with "Well, I'm a bit of a d---head, but I'm ---- "(name deleted). It's like brain poison - everytime I have to introduce myself, this phrase runs through my head and I have to struggle not to smirk.

Anyway, I have had a cheap (and irritating) telescope for a few months and due to a recent improvement in my finances I am looking to get a new telescope. After much thought I have (sort of) come to a decision based on the following premises:
My car doesn't work and I have a new mortgage (can't afford/ don't want to get another car), so I'm stuck with the light polluted Brisbane skies. Conclusion - small(ish) aperture
The henceforth mentioned mortgage is on a flat with no backyard so I need to take this to the park. And I'm lazy. Conclusion - (very) portable
I am a bit of sociophobe that simply cannot turn up to a bunch of people who are enjoying themselves and start asking questions (unless I'm drunk, and I get the feeling that would be frowned upon). So learning from people at star parties and astronomy clubs would not be sustainable even in the short term. I know where to find the bigger planets but nothing else. Plus, I get much more pleasure from the hobby through observing than 'hunting'. Conclusion - Goto mount.
I currently have a 90mm refractor on an eq2 mount that is too shaky past around 100x. It gets pretty annoying when a stranger would ask for a go (I'm in a park & everyone loves telescopes) and touch the eyepiece, knocking Mars completely out of view. Conclusion - small size tube/ sturdy mount.From the above, I am fairly sure I want something from the Celestron Nexstar SE series. The only thing I am having trouble deciding on is whether or not I get the 4" or 5" aperture. I have spent the last few weeks on various forums, but still feel like that donkey that starved to death between the two bales of hay.

Any advice or opinions would be appreciated. Any at all. If you think my dot points are misguided, please let me know. But the answer I'm really after (unless there is a spectacular logical fallacy in my reasoning and you point it out) is whether it will make enough of a difference to be worth the extra $400 to go from the 4 inch to 5 inch aperture.

Thanks!

P.S. Any ideas what I could do with the refractor once I get my new scope?

[Blue Skies]

5" for sure! That extra inch will make a difference, particularly with the planets.

[ballaratdragons]

Keep the refractor as a guidescope :D

Seriously, you might be able to swap the refractor for some good EP's. Place a notice in the Buy/Sell section in the 'Trade/Wanted' (http://www.iceinspace.com.au/forum/forumdisplay.php?f=32) area and see how you go :thumbsup:

[Solanum]

Hi,
I'm pretty new to the observing game myself, and there is a large number of people here know more than me, but are you REALLY sure you want a 4-5" Nexstar? When I was looking for a scope I was debating a Meade ETX125, which is very similar to what you're suggesting. The standard advice on this forum is get a Dob. Eventually, I followed it and am really glad I did. Going from 5 to 10" aperture is a BIG difference in what you can see.
Given the difference between refractors and reflectors potentially you aren't going to be able to see much more in the Nexstar 5 than in your current scope - though presumably the optics will be much better. I think you may be disappointed.
Given you want something easy to move, have you considered a somewhat larger, better quality refractor? (note I don't have one so haven't much idea of cost, might be a fair bit).
If you can be bothered carrying an 8" dob into the park you would have a whole new experience and save some money (they're portable but not all that easy to carry about).

[ballaratdragons]

If you did want to go the 8" dob way, and are worried about carrying it, you can make a sling to carry it. Quite simple to do and the 8" is light. but awkward, but the sling takes away the awkward.

And the base is light and comes with a carry handle :thumbsup:

You say you want GoTo, but no GoTo is very light to carry to the park, and they can take a while to polar align each time.

[Gargoyle_Steve]

How much are you willing to spend all up?
Here's an alternative recomendation for you to consider.

Buy an 8" dob - $500 inc delivery.
Lets say $600 instead, get a collimation (guide) tool as well.

Buy a furniture trolley to move it easily - $50 max at Super Cheap Car accessories.

(Dave Waldo, one of our local SE Qld members here, modified his simply and cheaply to also function as his height adjustable observing seat (http://www.iceinspace.com.au/forum/showthread.php?t=16656&highlight=height+adjustable+seat+tr olley+dob).

http://www.iceinspace.com.au/forum/attachment.php?attachmentid=22207&stc=1&thumb=1&d=1169251168 (http://www.iceinspace.com.au/forum/attachment.php?attachmentid=22207&d=1169251168)

Another local member (Dr Morbius aka Randall) bought himself a Digital Setting Circle system 2nd hand here on the forum for $200, a quick bit of cunning repair and it was singing like a bird at Astrofest recently - but even if you have to buy the best and pay brand new price.....

Buy an Argo Navis for the dob - $1000
This will make the scope PUSHTO not GOTO (ie your muscles move the scope, the Argo navis tells you precisely where to push it to) but the Argo Navis system is arguably better than any GOTO you're likely to buy.

Total cost : $1650 - 8 inches of aperture, best guidance system money can buy (and totally Australian product), easy to wheel to the park, observing seat included!

How much Nexstar aperture can you buy for that price?

[ballaratdragons]

I can just picture schmourghenne or Everard wheeling their trolley down the street :lol:

An 8" dob with a carry sling and no-one would take a 2nd look, but a trolley down the street! That would make me look! :lol:

Great idea Steve, but geez, wouldn't it look funny :rofl:

[schmourghenne]

Thanks for the fast replies, people!

I am interested to read that two people are saying go 8" or bigger. As far as aperture is concerned, I have been under the impression (from what I've read) that light polluted skies mean that large apertures ie > 6" are generally wasted.

Anyway, the nexstar 4 has a central obstruction of 11% by area, which would give me a slight boost of around 15% light gathering. The 5 has a central obstruction of 12% by area, which would give a big boost of around 70% over my 90mm refractor. But does that really make an appreciable difference for light-sky targets? (That was a real question - I wasn't being rhetorical, even though its sounds like it... :))

Also, the nexstar 4 weighs about 9.5 kg with tripod while the 5 has a total weight of around 12.5 kg. The physical size is also a big issue as I find I need three hands now for the OTA, the tripod (I used to carry the tube and mount assembled, but that was very awkward) and accessories bag.

The main things that drive me crazy about my current telescope is firstly the shakiness which I cannot fix despite replacing everything with steel and brass. And secondly the focuser which is so stiff that winding it moves the whole scope. It's also the little things like the declination circle being out by 3-4 degrees or the eyepiece that came with it rattling for no reason that make me feel like I am using something pretty ordinary. :mad2:

I think, too that I am at best a casual observer/dilletante in that I enjoy looking at an object much more than finding it which was my reasoning for a goto mount. I would much prefer to just hit a button and be looking at what I want to look at. I am intrigued by the suggestion that auto aligning can be difficult however.

Call me Shirley, but the thing I am most hesitant about (scared of?) with reflectors is collimination. I'm sure there are several indulgent guffaws greeting that admission, but I have a tendency to laziness in that when something recreational gets difficult, I find a reason to not do it any longer. There's a long line of ex-girlfriends that will attest to that... :rolleyes:

I hope I'm not appearing to be argumentative, but the difference in aperture is not so much of an issue for me as portability and ease of use. At the moment I'm at the start of the hobby and looking for a scope that's light and easy to use. That's not to say that I won't go to the 5 inch if it is really worth it, but as I mentioned before, I get the impression that there is no real difference in smaller scopes until you get to 6-8 inches or more.

[Gargoyle_Steve]

Ah well - if someone's a sociophobic carless flatbound astronomy enthusiast who wants as much aperture as possible with smart guidance for minimum cost you have to pay a price somewhere, don't you?
;)

I reckon that's such a clever idea for a package I might just go ahead and set that all up myself!

Oops, hang on, I already did! :lol:
Except mines a 12" dob, and I do have a car and a yard - but it does have the Argo Navis, and I do move it around on a trolley!

To answer another of your comments / questions schmourghenne as far as light polluted skies go more aperture will still show you more objects. There's no substitute for dark skies, but since we can't get you past the local park it looks like you're stuck with skyglow, etc. 5 inches does give a good jump up over the 90mmm refractor, but you will still find yourself wishing things were brighter, better defined - that's where the extra aperture helps.

[Gargoyle_Steve]

PS : Aperture not so important? OK, buy a 6" dob - $299 at Andrews Communications, even lighter, save the extra money to pay someone to collimate for you!

*grin*

[schmourghenne]

Wow.

Now I'm disappointed that I can't go to the dark sky camp you are touting, Steve.

Just think, a whole weekend of you being snide whenever you join a conversation. We could all parse our sentences slightly grammatically inexact and you could point it out in between telling everyone how you are the coolest astronomer to walk the face of the earth. Good times...

Perhaps if you read the post, you'd see that I'm not talking about "most aperture for minimum price", I was actually asking whether there is an actual or theoretical difference in seeing between a 4" or 5" scope in the city.

But that's fine, Steve. I'll work it out myself.

Thanks [cough] for your "help".

[nightsky]

G'Day Schmourghenne,
Your in a similar position that I was a year ago, I wanted a Goto scope which was light to carry and easy to set up.Although I do have a backyard I'm to old to be carrying a bigger and heaver scope in and out of the house so I bought a Meade LX 125,as the lads have said in this thread and it applies to most people "you'll want a bigger scope,the larger the mirror the more you will see" known as "aperture fever" Thats what happened to me,so I bought a Meade LX90 8",then I a bought a Meade 10" and now have that in my Observatory. So here's my 2 bobs worth,taking into consideration that you live in a flat whether ground floor or top floor. I would be going for a scope similar to the Meade LX 125 you should be able to get one for well under $1000 the only hassle you will have is you will have to setup and align the scope each time you go to the park,also you will be going through a lot of batteries.And don't be to hard on the lads believe me they mean well they have given me and others a lot of good advise over this last year.Anyway whatever scope you decide to buy I wish you luck and clear skies.Here are a few links to check out second hand scopes in Oz.
Cheers
Arthur
http://www.astrobuysell.com/au/index.php
http://www.geckooptical.com/cgi-bin/gecko/index.cgi

[Starkler]

I really don't know where this comes from. Whilst its true that all scopes will give their best under dark skies, its my experience that small scopes are less useful under light polluted conditions than larger ones, unless looking at planets and the moon only.

With a larger scope you can still bump up the power to mitigate LP and darken the background. In contrast a small scope runs out of light very quickly at higher magnifications, and this is compounded by ambient suburban light and lack of dark adaptation.

In short, I find small scopes next to useless in light poluted conditions.

[rmcpb]

The beauty of a larger scope under light pollution is it can handle the narrow band filters better because it simply gathers more light from the object of interest which gives better viewing.

As for your first question, its a no brainer, go for the largest aperture you can handle and if that is a 5" then that is it and it will be worth it.

[nightsky]

G'Day Schmourghenne,
This link will show you just how easy it is to align the Meade LX 125 if you decide to buy one ,Also afaik you don't have to polar align for visual observing.
http://www.meade.com/educational/etx%20videos/index.html
Cheers
Arthur

[ballaratdragons]

Touché! :lol:

[schmourghenne]

Thanks Arthur.

I have been looking for a decent Australian second hand site for telescopes. Plus, I think I might have found a pretty reasonable deal on a 125 with accessories - hopefully it hasn't already gone.

[Blue Skies]

The comment about the 6" being better under light pollution is an oldish one, a bit like the old adage that a 4" refractor is the equivalent of a 8" newtonian. Not any more!!!! In the past the quality of refractors was far better than relfectors but the reflectors have caught up and are more or less equal (unless it's Astrophysics refractor, of course, they are the best. And yes, I have looked through a 4" Astrophysics refractor so I do know what they are like.) I think I'm really trying to say is don't take a rule of thumb comment as the definitive, there is often no 'right' or 'wrong' with telescope situations, only what ever produces a satisfying experience is the 'right' choice to make, be it big or small. I often say there is no shame in having a small telescope, the only shame is not using it to it's fullest potential.

However I think Schmourghenne and thought his situation through reasonably well, and a small goto Maksutov like the ETX125 might be just what he wants. I still say go the 5" if thats around the size you want. As large as you are willing to carry!

Gotos can be hard to set up, they are not always as whizz-bang-Bob's-your-uncle as the advertising suggests, which is what someone else has tried to point out, but you've already had some experience with using a telescope and finding your way around the sky so this might not be such an issue.

[Gargoyle_Steve]

Schmourghenne I'm not quite sure what prompted your sarcastic response to my genuine replies to your posts - you had asked questions, I was trying to reply and make a suggestion in a forthright and honest fashion, no disrespect was intended. I went to some effort to search for the thread on Dave's trolley, knowing that a picture was worth a thousand words. I now feel VERY happy that I went to such efforts to provide you with information.

Those here who know me, and there's more than a few, know that the portrait you have painted of me is far from correct. I am NOT self opinionated, in the habit of making snide remarks, a member of the grammar police, etc. My comments re carless, sociophobe, etc were directly taken from what you had said about yourself - except you also described yourself as lazy, I didn't repeat that for fear of giving offense.

As for the comment I made about most aperture for minimum price the fact is that MOST people want to achieve that (myself included) - unless you are in the habit of preferring to spend more money than is necessary to achieve a goal. Thats why I suggested a dob, that's why I have one myself. You had also mentioned how much having a shaky mount irritates you, again at the price there's no more stable mount than a dob.

From your original post I took it that you were a person who had a sense of humour - I was obviously wrong. I won't offer other suggestions, I'll simply hope that you find a scope package that suits your requirements.

[iceman]

I agree with Steve.. I think the sarcasm directed at Steve was unwarranted. He was offering genuine advice that the rest of us would've offered too.

As for second hand scopes, the IceTrade Classifieds are the largest and busiest 2nd hand astronomy classifieds in Australia. Keep an eye on them if you'd prefer 2nd hand rather than new.

[schmourghenne]

Steve, from reading your reply, I see that I completely misinterpreted your reply and I wholeheartedly apologise for my aggressive response.

In most of the forums I visit there is a culture of treating new posters as second-class or unworthy. I react badly to this type of culture wherever it exists whether it is on the internet, at work or anywhere else.

From reading many of the posts on the Ice in Space forums, I see that this is not the case here and again I apologise to you and anyone else I may have offended.

[Gargoyle_Steve]

No problem - we were ALL newbies here (except for Mike of course!) and members of this forum generally are all pretty much mature and considerate enough so that no one, newbie or pro, ever gets treated badly.

I was brand new to this forum and to astronomy only 18 months ago, and it was the wise advice that I received here that has guided me in most, if not all, of my astronomy purchases. I know I have a hell of a lot to learn yet, but from my perspective as a "recent" newbie who has been through the same sorts of questions that you're going through now, I thought my input as to an alternative suggestion may be valid to your decision making process.

I look forward to hearing what you end up doing scope wise, and of hearing how great your "first light" session with it goes.

Remember that there ARE groups of IceInSpace members who meet up regularly (each month around new moon) and that you would always be welcome at any number of these meetings should you ever wish to attend.

Cheers!

[ngcles]

Hi Schmourghenne,

I'd have to very much agree with the advice that Steve offered.

Have to admit up front I'm a big fan of Newtonian reflectors that offer by far the best value for money.

Specifically regarding the questions you are looking to get answers to.

The true power of a telescope (assuming good optics) is the light gathering power. You can compare different apertures simply by comparing the square of the diameter. The central obstruction is negligible in assessing light gathering power.

4" = 16

5" = 25.

Therefore the 5" will produce images that are nearly 50% brighter than the 4" and means you can see objects 50% fainter. It will also have slightly better resolving power meaning you will get a little more detail in the image too.

However the 8" aperture suggested has a light gathering power of 64 -- 300% more light that the 4" and 250% more than the 5" and has about twice the resolving power.

An 8" dob doesn't generally come with goto but as pointed out, if fitted with an AgroNavis (the best DSS in the world - and Aus made), you can have push-to. A dob with push to is _dead easy_ to use. The Autostar and Nextstar systems are good but the Argo is even better -- wouldn't be without it.

Unless you have a midget car (assuming you get it fixed one day or another), the tube will fit across the back seat, and the mount in the boot.

As you have already recognised, it will need collimation from time-to-time. I know this can seem frightening, but it is like riding a bicycle. I know I'm an old-hand but I've got a truss-tube dob that is more demanding generally than a simple hard tube. Out of the ute after an hour riding the road it takes 2 mins at most to get spot on. The first time you do it it will take 20 minutes, the second time 10, the third time 5 mins etc etc. It isn't hard I promise you if you have the right tool (also cheap). Owning a newtonian means you should also remove and clean the mirror occasionally, but if kept capped it only needs to be done every 12 months. Remember a Schmidt corrector plate also needs occasional cleaning.

Owning a Schmidt will not relieve you of the need to collimate occasionally and collimating a Schmidt is somewhat harder and there are no tools to help. You have to do it on a star or an artificial star.

In terms of price, the 4" Celestron and the 8" dob with push-to will be comparable. The 5" will actually be a bit dearer than the dob. You don't get tracking with the dob, but you do get a vastly better view due to the increased aperture. Which is most important to you?

In portability, the 5" won't be easy to tote around all in one go -- your hands will be very full. The 8" is certainly a bit harder and bulkier, but with a sling for the tube you can carry the whole lot short distances without too much hassle.

Yes the dob is heavier and bulkier but is not real hard to move around. It will take up more room at home but if stored assembled with the tube upright and capped it will only take a foot square of floor-space somewhere. All catadioptric telescopes are prone to dew build-up on the corrector so counter measures need to be taken. Attacking this problem properly can be a mite expensive.

In the end, buying a telescope is a bit like buying a car. It is a personal choice and is made with your personal needs in mind. In my opinion you should carefully consider the advantages a 8" with push-to has to offer. It's has some very considerable advantages. But it is after all your choice.

Re this light-pollution business, it is an urban myth -- aperture rules.

Hope this is some help.


Best,

Les D
Contributing Editor
Australian Sky & Telescope