Advice on first Telescope

[aganod]

Hi I am looking at my first telescope and would like some help choosing.
The ones I have looked at so far are

Celestron NexStar 127SLT Computerised Telescope

Celestron NexStar 130SLT Computerised Telescope

Skywatcher Skymax 127 (eq3) with the Supatrak auto-tracking mount

Skywatcher BKP 130.

I was looking at using this first one to learn my way around the sky and locating objects.
I am already looking at a 12 inch Bintel Dob after learning a bit more.
Any one that has any advice would be appreciated.

Thanks David

[Amaranthus]

Do you have some links to the various models you have in mind, so we can see more info? I think the 1st is a Mak and the 2nd is a Newt - not sure about the others. GOTO would be an advantage, especially if you are in light-polluted skies.

[Allan_L]

Hi David,
Welcome to IceInSpace :welcome:
Have you read this two part article: General Principles for Choosing your first Telescope
http://www.iceinspace.com.au/63-260-0-0-1-0.html

Its a few years old now, but still a good place to start.

Where are you located?
The best advice is to get you along to a (preferably free) observing session, where you can look through various equipment, and talk to owners who have travelled the path you are starting upon.

In reference to the smaller 4 scopes listed:
To steal a quote from part 2 of the article, be careful you do not finish up with a telescope that can automatically pinpoint countless objects that are far too dim for it to see.
And...
Any object within the grasp ... is either visible to the naked eye or fairly findable with a decent star atlas.

Having been down this road myself, my experience is that (they are all good scopes but) you will soon run out of things to see with these scopes, and be running for the larger aperture DOB before too long.

My recommendation, to save some time and cash, look at buying a DOB up front, 8" is good, 10" is better, 12" is starting to get a bit awkward to move about. And you can get it with GoTo up front too.
Personal preference: I would recommend Skywatcher goto DOB or an Orion.
This one looks to be excellent value http://www.bintel.com.au/Telescopes/Dobsonian/Orion-SkyQuest-XT10G/1472/productview.aspx
But the Bintel (GSO rebadged) and Meade are also highly regarded by many on this site.

Good Luck with your purchase

[Pinwheel]

Hi David & welcome to IIS, I have a Bintel 302-b 12" Dob. It's a great scope & some even call it a Light bucket. The only negative really is it's size & weight, It's like moving a hot water system around...:lol: But mounted on wheels helps it to get around. If your in my area, your most welcome to have a closer look.

[PSALM19.1]

Hi David,

Truth be told, all of the scopes mentioned will make you say "wow" quite often as you gaze heavenward! I learned my way round the sky the old fashioned way...without any Goto and electronics...this is maybe the hard (?) way to do it, but has the HUGE advantage of meaning you can spend less money on electronics and more on aperture! An 8" Dob will only set you back $500 or so and give superior views than the smaller electronic scopes you mentioned. If you can handle the size and weight of a 12" Dob then I say, go for it! Honestly, it won't take that long with a bit of practice to find your way round the sky and even a 12" Dob will not cost the earth for magnificant views! Lots of fun ahead...!!:welcome:

[AstralTraveller]

I know people who have bought a goto to learn there way around the sky and it hasn't worked. The best that happens is they learn a few calibration stars and not much else. Other times they don't even manage that. I'm afraid nothing beats a star atlas (I used Nortons) a red torch and a pair of small binocs (say 8x32) if you want to learn. There are real uses for goto but IMHO teaching isn't one of them.

As for the scope, if you can handle the 12" why not put the money you save by not buying the 5" and put it towards an Argo Navis?

[brian nordstrom]

:thumbsup: mmm m :question: , 12 inch and 'Agro Navis' , nice .
Brian.

[raymo]

Unless you have a large vehicle I would go for the collapsible Flex Dob;
it holds collimation very well, and is more convenient to transport.
raymo.

[aganod]

Thanks everyone for the great advice. I am still deciding on what way to go.
I was thinking of starting with a smaller one with the electronics so I could easily take it with me sometimes and then getting the dob to just use at home.
I live on the coast just south of Perth in WA. I was also wanting to start trying
some photography as well.
Here are the links for 2 of the telescopes.
http://www.celestron.com/browse-shop/astronomy/telescopes/nexstar-127slt-computerized-telescope

http://www.celestron.com/browse-shop/astronomy/telescopes/nexstar-130slt-computerized-telescope

The other 2 I saw them in a shop and have included photos of the details.

http://s30.postimg.org/yvom6wspd/sky1.jpg

http://s30.postimg.org/u67v9sggh/sky2.jpg

Thanks David.

[Pinwheel]

If you want to do Astro-photography then that rules out a Dob. You simply won't have back focus due to it's focal length. You should look for an 8" F4 Newtonian with a solid EQ mount with star tracking ability.

[raymo]

That blanket statement is not right Doug; Skywatcher Dobs work fine
at prime focus and with EP projection.
raymo

[OzStarGazer]

Yes, raymo is right:
http://www.iceinspace.com.au/63-201-0-0-1-0.html

[Pinwheel]

I wish I knew that earlier when I bought my 12" Bintel Dob!

[raymo]

It has been stated by myself and others on several occasions when this
subject has come up, but it is easy to miss individual threads amongst
thousands of them.
raymo

[Renato1]

Personally, I don't think you'll learn anything much about the sky using a GOTO. And if eventually you get a GOTO Dob, well it won't matter.

My thoughts are that if you are eventually going to get three or more telescopes, one of those 5" computerised telescopes will be fine.

But, I think everyone should give consideration to having a small short tube refractor that they can pick up, walk out with, and start viewing. They are extremely handy both in their own right, and for iffy nights when you might only get 20 minutes of viewing and so can't be bothered lugging out the heavier or more complicated telescopes, and for when travelling.

Regards,
Renato

[raymo]

I don't wish to hijack the thread, but just a quick comment. Doug, if
you're good with D.I.Y. you could move the primary mirror up the tube
the required amount, or look for a new or used low profile focuser if your scope nearly comes to fo

David, if you do get one of those small GoTos, don't get the SLT 130. The tube is too long for the
single arm mount, and vibrates severely when touched. The 127 SLT is much more stable.
raymo

[OzStarGazer]

I think you are right! This is similar to all the kids who are not so good at maths because they always use a calculator or an app... :lol:
PS: They also say that you learn better in a crisis than in a normal situation. So when you have to find something yourself and make an effort it will stick in your head somehow...

[cometcatcher]

Nothing sticks in my head for very long. :P I like goto, it is wonderful. :) Try finding a magnitude 9+ comet without digital R.A. / Dec readout by star hopping and see how long it takes.

[Camelopardalis]

As you can see David, there are those who enjoy the journey and those that enjoy the destination :lol:

Personally I started off a long time ago (in a far away galaxy...) with a manual mounted refractor and got a huge amount of satisfaction from it. I've recently added one added to my armoury again. You can do a lot worse than something like a 120mm achromatic refractor on an AZ3 mount.

It's always good to learn the sky, but it'd remiss to dismiss GOTO. The best thing I like about goto scopes is the tracking...once you've found an object it continues to keep it in the field of view as the Earth turns. Especially useful at high magnification.

The main issue IMO with the SLT scopes are they are motorised only...when your power source is exhausted, that's it, time's up. At least with a manual mount or a Dob mounted scope you can still move it, even if you have to track manually.

I usually use an equatorially mounted scope and while most of the time it's powered, motorised and I'm using the goto, when the battery runs flat I can just release the clutches and drive manually...it's good to have both :D

Then comes the issue of aperture...more aperture allows us to see more detail and/or fainter objects. IMO about 8" is a sweet spot where there's enough aperture that you can see plenty of detail on planets and globular clusters (for example) but the scope still remains relatively manageable.

If you have a local telescope shop or astronomy club or society, I'd recommend going along to have at these things for yourself. A 12" Dob for example is quite a beast :D

[OzStarGazer]

Can a GOTO also be used in normal mode with a finderscope?

[Camelopardalis]

Depends on the mount...some mounts, like the SLT and SE series from Celestron have no clutches to release, so moving it manually can (and likely will) damage the motor gears.

Many of the goto Dobs are built to allow manual pushing without loss of sense of direction, so the computer knows where it is, and tracking continues once you let go.

[Meru]

Hi Dave,

Welcome to IIS! As Allan has pointed out the link, have a read. It's quite good to read. I would very much recommend you purchase a 8" dob. I owned both a 10" & 8" dob and have to say, unless you got dark skies the extra weight and hassle of moving a 10" is definitely not worth it (for me anyways :P).

I believe Dobs are the best type for visuals and especially for beginners. The money goes towards good optics and simplicity of use - something you definitely need whilst in the dark learning for the first time. Anything with computers will probably make you spend more time reading the manual than gazing! Plus they have better resale value than the SLTs. I personally think the SLTs are just a good marketing strategy for making money of those who haven't done their research which you clearly are :)

Try joining an astronomy club or see when the next public viewing night is (Bintel can probably help you there).

[raymo]

On the SLTs you can slacken nuts on both axes so they can be moved by hand without damaging anything. Most modern day GoTo EQ mounts
don't have any manual slow motion controls, but the motor controls can be operated to point the scope where you want using the finderscope
without going through the GoTo setup procedure, and you can set it to
track your target.
raymo

[Allan_L]

Not sure about other DOBs, but a Skywatcher GoTo DOB definitely can.
You can use it manually, without even switching the control system on.
You can use it switched on and star aligned, but still manually push it to objects (the system still knows where it is pointed).
You can use it switched on but not aligned. This will be for manual pointing, but you can use the motion buttons to slew manually to an object.
You can use it switched on, and just levelled, pointing North, for manual pointing to an object, and it will Track it in sidereal mode.

It has a slip clutch system that allows any combination of manual pushing the scope fully or partially to objects.
I like to use the finder to push the scope to the near vicinity of an object quickly, then hit the slew button for the system to fine tune to the object. (its is quicker, and saves battery power)

Celestron Nexstar SE series definitely NOT.

Celestron CPC series has torsion nuts on both axis, these can be slackened to allow manual movement of the scope, but doing this will throw out the star alignment.

[julianh72]

I have a 130 SLT (Newtonian) which I bought second-hand. You can move it easily by hand in Altitude (up and down), and you can adjust the tension in the Altitude bolt so that it doesn't slip. However, it seems to be absolutely locked in Azimuth (side to side), and I have seen numerous forum posts from owners of SLT schools which confirm the same thing. I'm not game to push it any harder to see if it can be manually slewed.

So an SLT is really only suitable as a powered scope. It can chew through the 8 x AAA batteries pretty quickly (perhaps 4 to 6 hours use), so I strongly suggest having two sets of 8 x AAA NiMH rechargeable batteries, and just swap and recharge after each night's viewing. On a long night's viewing, you might even need to swap out part way through the night. (Or do what I have done, and get an external rechargeable 12 volt battery pack - I have a 7 amp-hour SLA (Sealed Lead-Acid) which is quite compact, and good for several night's viewing.)

As for the tube vibrations mentioned by Raymo in an earlier post - they're noticeable, but not excessively so. Make sure all tripod bolts are nice and tight, and make sure the dovetail is also properly tightened, and the Mount is perfectly fine for visual use. I have actually put my SLT mount onto a heavier EQ-2 aluminium tripod, and it's actually very stable indeed for a low-cost GoTo telescope.

[Pinwheel]

Thank's Raymo I am aware of the mod to remove around 2" of tube length. I just don't want to hack my 3 month old Dob just yet!

http://www.iceinspace.com.au/63-441-0-0-1-0.html

[raymo]

I used to hang a small car battery under the tripod which made it much
more stable.
raymo

[OzStarGazer]

Thanks for the replies re using GOTO in normal mode! :)

[AstralTraveller]

Well, there you go - I'd say the exact opposite. A 10" gathers 100/64 = 1.5 times the light of an 8" for about 1.4 time the cost. But, more important (and after you have forgotten the cost), the tube lengths are basically the same so anywhere you can fit or carry an 8 you can also fit or carry a 10. I put a carry handle on my 10 and that helps a lot. No more cradling the tube. Just carry it in one hand like a large, odd shaped, suitcase. My first scope was a 10" f/8 (that was a beast to move!) and I've always found eights to be under-powered.

[Pinwheel]

Before I bought my 12" F=5 dob I had an 8" F=4 on an EQ mount, both are timely & heavy to move from house to my viewing area. However the views from the 12" are so much more superior to the 8", there really is no comparison.

[raymo]

Hi Doug, I have to agree that the 12 is much better than the 8, but we
need to remember that we were comparing the 10 to the 8, and the difference is nothing like as great. The view through my 10 Dob is better
than my 8, but not greatly so. The only time that the difference is really
noticeable is when scanning starfields, when many more stars are
visible.
raymo

[Pinwheel]

Agreed, My point is these day's you can buy an 8",10" or 12" for pretty much the same money plus or minus a hundred here or there.
All input is important to a newbie thinking of taking the plunge.

[aganod]

I picked up a second hand Saxon 90 Maksutov-Cassegrain to try out why I am deciding what to do. Will there be much difference between the 90 and the 127 in viewing? What are the main differences between the other types of scopes and the Cassegrain?

David

[raymo]

There are many basic types of scopes, and even more hybrid scopes that use features from two or more designs. You could write pages describing them, so I suggest googling " astronomical telescopes".
raymo

[noeyedeer]

don't discount that dobs with an app like skeye (it's free on droid) can be used as a push-to if you Velcro your phone to the scope n do a star alignment (the more the merrier), have it level .. etc.

even just scanning the sky through the eyepiece is an experience and then stopping on some fuzzies and chucking in a higher power eyepiece reveals something totally astounding.

if I were you I'd get the dob .. learn the sky manually it makes it more of an experience .. instead of pressing a button, and possibly getting frustrated ..
matt

[julianh72]

Matt,
I have no problem with your argument that a Dob is a good way to get lots of light gathering power for a low purchase price, and I agree that using something like SkEye is a great way to add "PushTo" to your Dob ...

But I'm intrigued why you think strapping a smartphone onto a Dob and using SkEye to turn it into a "PushTo" is somehow philosophically different to using a GoTo powered mount (with or without an interface to a planetarium app on your computer / phone / tablet)?


Both require that you align your scope - and the procedure is pretty similar for both.
Once aligned, both allow you to check and refine your alignment by targeting a visual target in the area of your ultimate target. (And this can be a huge aid to track down the "faint fuzzies" that are on the limit of your telescope's capabilities - it is good to know that what you are seeking is indeed in the field of view, rather than just HOPING that it is in view after a bit of star-hopping!)
Both allow you to point to your target reliably, but one drives the scope and stops on target, whereas the other requires you to push the scope and will tell you how far off you are.
Both could be used with no almost knowledge of the night sky - which is "a good thing" in my book - the easiest way to learn the night sky is to ask your telescope to go to Jupiter (or Orion, or Acrux, or ...), get it in view, then look up and see it in the sky.


"Horses for courses" and all that.

[noeyedeer]

hi Julian,
I was just putting it out there that a dob can be used as a push to.

it's nothing philosophical, the OP asked a question and I was adding some info that hasn't been stated about considering the dob.


matt

[aganod]

Wow tried out the scope I got for the first time tonight and got some great views of the moon. It sure is great when you see it for yourself rather than in photos. Discovered the Saxon I bought has no finder scope so it was not easy to find anything else, the moon was easy to find.
David

[Amaranthus]

Get a low-cost red dot sight - effective and easy to fit/use

[opensea64]

I Highly recommend a Telrad finderscope. Although very simple in design its very easy to use and collimate. I found it better than red dot finders as the one I had (sold since) needed allen keys to collimate where the Telrad has adjustable knobs.

[raymo]

You were very unlucky then, as most red dot finders have adjustment
knobs on both axes; even cheap ones. I have a cheap RDF and a Telrad, and have no particular preference, except that the RDF was half the price of the Telrad. If choosing an RDF, just make sure to get one with
variable brightness.
raymo

[julianh72]

+1 for a Red Dot Finders!

The Telrad is arguably the "best of breed" , but even the basic RDF that you can get from Bintel and other sources for under $40 has easy thumb wheel alignment adjustment on both axes, and variable brightness.

[Steffen]

Actually, some of the four-reticle ones (like the WO of which I have two) require an Allen key for alignment, but those a very well made, all-metal and hold their pointing accuracy across many observing sessions. The battery in them also lasts forever. I can't count the times I've forgotten to turn them off when packing up, I've never been caught with a flat RDF battery. My only niggle would be that even at the lowest setting they can be a tad bright under very dark skies.

Cheers
Steffen.

[Monstar]

I have only ever used one type of finder, the cheap RDF that came with my scope and am very happy with it. Only a couple of minor niggles, the azimuth adjuster is in line with brightness adjuster and at first I sometimes used to turn the wrong one, this doesn't happen anymore as my fingers can now recognise the slight difference in size. The other niggle is more me than the scope in that I keep forgetting to turn it of!! This does point to a good point though as I still haven't needed to change its battery

Edit: have just re-read Steffen's post and seems he has exactly the same thing with the on/off and battery so it must be true.