Torn between a large aperture Dob and smaller scope with tracking mount

[Spud]

My only real post away from the Welcome forum, so hi .

Looking for a bit of advice on my first decent scope. Really need to make the right choice from the start as finances aren't going to allow me to buy anything else in the foreseeable future.

Love the idea of a large Dob to see more of the DSOs, but I also fancy having a go at taking a few photos of closer objects.

Something along the lines of a bargain second-hand Skywatcher 250PX with an EQ6 mount would be great, but I don't rate my chances.

Digital camera I have is an old Nikon 995, not sure how suitable or what limiting factors this has on buying a scope suitable for astrophotography, but I certainly can't afford a new camera as well as a scope.

Have zero interest in a Go To type mount, would rather find objects myself, which I see as part of a valuable learning process I need to go through.

Initially I was thinking of a 12" Dob, but now I'm thinking it would be quite difficult to handle and wouldn't allow any photo opportunities beyond one or two of the brighter objects.

Ideally I'd like to keep costs below £700.

TIA

[philsail1]

Hello "Spud!"

I've never owned a "Dob" so I can't comment on the pros and cons of owning one. However, if you have even the faintest desire to take photos through your scope, then I would suggest going for either a Celestron CN8 (8" Newtonion Reflector) mounted on their CG5 motorised mount, or a Skywatcher 8" "Explorer" Newtonion reflector on their celebrated HEQ5 motorised mount. Either of these scopes will give you a lifetime of pleasure (Unless you do succumb to "aperture fever"!!).

I've owned the Skywatcher, and it is an excellent all round scope, which gives very nice views of the Moon, Planets, starfields and most of the deep sky objects.

The reason I mention the Celestron CN8 on the CG5 mount, is that the scope is virtually identical to the Skywatcher, and the mount is very good (I've got one), but a bit lighter than the HEQ5 mount, which does make it a bit easier to move about.

Both mounts (in my opinion) track excellently - though the general opinion you will receive, is that the HEQ5 is the one to go for. The Celestron mount is the simpler of the two.

If you haven't already done so, do think about "portability," "where are you going to set your scope up," and "where are you going to store it," before rushing in to buy.

Also, wait until you have received more advice from colleagues on Star Gazers - as there are some very good "Refractor" telescopes out there, which might suit your needs better than a reflector - although for the money, you do tend to get more "inches" of light gathering power in a Newtonian reflector.

By the way, I have a basic Canon A570is Digicamera with which I take "Afocal" astro shots, and it produces very good photos of the Moon and Planets, and reasonable photos of even some deep sky objects. As long as your digicamera has some manual settings (especially a shutter speed of at least 15 secs min for deep sky stuff), it will take decent shots. You can buy a "clamp on" adapter to attach you camera to the eyepiece of your scope too.

Best wishes,

philsail1

[Spud]

Thanks philsail1

Some good points you raise there.

Been looking for the two scopes you suggested.

Found a Skywatcher Explorer 200P HEQ5 Syntrek, not sure if that's the one, but it's out of my price range at over £850, unless I find a used one.

Failed to find a Celestion CN8 and so far only the CG-5 GT GOTO mount. I'll keep looking though.

[Sam]

Hi Spud,

I have a 8" reflector on a EQ6 Syntrek. I used to have it on an HEQ5 and that was a brilliant setup. The 8" is a good size for seeing DSOs and looking at planets. Having it on an EQ driven mount gives you the imaging option as well. Second hand kit should keep you under budget.

Sam

[Doc]

You can take photo's of the Moon and planets with a dob. If you are interested in DSO's then no a dob is no good.

If you struggle finding time for the hobby then a dob is much simpler to set up and to start observing. An Eq mount takes a while to set up and polar align.

Then you have the added aperture of a dob.

[Spud]

You can take photo's of the Moon and planets with a dob.

Initially I was thinking of a 12" Dob, but now I'm thinking it would be quite difficult to handle and wouldn't allow any photo opportunities beyond one or two of the brighter objects.

If you are interested in DSO's then no a dob is no good.

Are you sure about that?

[Ben Ritchie]

Personally I reckon it's better to think about what you really want to do ... imaging or visual ... and go for one or the other.

On the used market £700 will buy you a nice 12" Dobsonian, some nice eyepieces and will keep you busy visually for years ... but not ideal for imaging. Or it will buy you a HEQ5, a small apochromatic refractor (80ED, say) and a used 350D and you'll have a great budget imaging setup, add a ST80 and DSI/QHY5 as a autoguider when you have the money and that'll give you years of imaging fun. But the (lack of) aperture will restrict what you can see visually unless you've got cracking dark skies.

The middle ground is less clear-cut to me. Yes, your money should get you a 8" or 10" EQ-mounted Newtonian which will cover both visual and imaging, but it's still a compromise - not the aperture of the Dob, but bulky enough to tax the mount a bit, you need coma correctors for any sort of large chip DLSR/CCD and that's extra cash.

So (having been there, got the T-shirt) i'd look to go one way or the other for what you really want to do in the short term. They're not exclusive options, you can experiment with lunar/planetary imaging with a Dob, and do a fair bit of visual with a small refractor. But overall my view is that (on a budget) trying to do everything with one setup is a mistake

[Doc]

Yes Spud I'm sure.

There are quite a few websites dedicated to AP with a dob. objects like pplanets and Moon don't need long exposures so do not need to track the skies. Take loads of frames and stack them in Registax.

I have a 16" dob and have added wheels and handlebars and it's outside in One minute annd ready to observe straight away.

[rawhead]

Don't underestimate the time and hassle of hauling out and setting up a big scope on an EQ mount. Usually completed in the time it takes to cloud over....

I'd go for a 8'' (Easier to collimate) / 10'' dob....

Cheers

Jon

[Spud]

Doc

I misread your post, sorry.

I took it literally, i.e. "If you are interested in DSO's then no a dob is no good."

rather than

photographing DSOs with a dob is no good

[Doc]

Sorry Spud my mistake.

Visually a dob excells at DSO's.

[Spud]

Sorry Spud my mistake.

Visually a dob excells at DSO's.

No probs.

Just a quick visit to http://www.apostrophe.org.uk/ and we're all sorted.

[Spud]

Ben

I'm so glad I didn't rush into buying a scope. Your post makes total sense, cheers.

As you say I could do both visual and imaging with a 8" Newtonian, although if I had to choose just one then it'd have to be visual. So it's looking more and more like a Dob. Maybe I'll get a Dob and then think about saving for an imaging setup in the future. At least that way round I'll get to see more objects, I think.

[Spud]

Don't underestimate the time and hassle of hauling out and setting up a big scope on an EQ mount. Usually completed in the time it takes to cloud over....

I'd go for a 8'' (Easier to collimate) / 10'' dob....

Cheers

Jon

rawhead, I'm glad you mentioned that. When I've toyed with what size Dob to get, I hadn't factored ease of collimation into the equation. I knew 12" would be real hassle to get in the car, so 10" would be more suitable in that respect as well.

If I bought a Dob, would an unheated detached shed be no good for storing it?

[Ben Ritchie]

Maybe I'll get a Dob and then think about saving for an imaging setup in the future.

Worth remembering too that you can have a lot of imaging fun on a very limited budget - a lesson I wish i'd learned earlier. The temptation is to jump in with relatively long focal lengths, CCDs and all the gadgets that go with them but something like a DSLR with a 50mm lens only needs a very basic tracking mount, star-trail images don't even require that - look at "Dangerous Dave"'s star-trail images to see how good those can be.

Plus a bit of webcam imaging of the Moon and planets through the Dob and you might be able to get your imaging fix without spending much more cash - worth remembering how few clear nights we really get too, so the reality is that you can keep busy for a long time with budget-friendly webcam and widefield imaging before running out of things to image.

[Ben Ritchie]

If I bought a Dob, would an unheated detached shed be no good for storing it?

It's fine - I keep my 12" solid-tube in an unheated, detached shed without a problem.

For me 12" is fine, because i'm (almost) never putting it in the car - it breaks down into OTA and base and I just lug the two bits out into the garden. For frequent travel you probably want to look to either a 10" (or even 8") and/or a truss design rather than solid tube.

Solid tube is nice if you're not traveling though, as collimation is pretty stable - just a quick tweak before observing.

[Spud]

Whatever scope I get, traveling with it would be only occasionally.

I know if I buy a 10" I'll wish I'd got a 12".

Think I'll try and get to look through a 10" and a 12" before I decide on which to get, just to see if I think the difference is worth the extra expense and weight.

Cheers, Ben, I'm off to tidy the shed.

[John]

Do try and find a way of looking at and through some scopes if you can Spud. Physically a 12" dob is a very big piece of kit - in fact any 12" scope is a pretty massive affair. I upgraded from an 8" dob to a 12". The difference in the views are noticable but not earth shattering - the viewing conditions from my back garden are not ideal which takes the edge off the larger aperture I suspect. Under really dark skies I'm sure the difference would be more marked. I suspect the difference in performance between a 10" and a 12" would be much less obvious most of the time.

I keep my 12" in the house which means it needs 45 mins or more to cool before the images settle down. It is pretty manageble though and I suspect the only practical way for me to have a 12" aperture scope.

John

[Chris Stacey]

I upgraded from an 8" dob to a 12". The difference in the views are noticable but not earth shattering -

John

I would like to upgrade from my 8" dob at some point (I might put off getting a refractor and not bother stepping into imaging and just go all out for a "bells and whistles" dob instead). Would you recommend going for a say a 16" to get real noticable differences then?

[The Warthog]

If you really want to do astrophotography (which I believe is the Devil's work and best left to him ) or just for the sake of having a tracking mount, the Skywatcher 8" on a motorised EQ5 mount seems to be hard to beat. It's still a bit of a backbreaker to set up, but not nearly as bad as a 10", but it still gives you lots of light grasp, and fits well withng your budget.

[John]

I would like to upgrade from my 8" dob at some point (I might put off getting a refractor and not bother stepping into imaging and just go all out for a "bells and whistles" dob instead). Would you recommend going for a say a 16" to get real noticable differences then?

Having never looked through anything larger than my 12" it's difficult for me to say Chris. On paper the 12" should out perform an 8" by some margin and it does show fainter objects more easily and a bit more detail in the brighter DSO's but most DSO's are still faint and fuzzy at 12", just a bit less so than at 8". My viewing location does have some light pollution and, during the winter, there is heat rising from the surrounding houses all of which does not help and possibly affects a larger aperture more than a smaller one.

I'm not dissapointed with my 12" scope - having been in the hobby for 25 years and having owned loads of scopes my expecations were realistic and the 12" does show more and has more potential than any scope I've owned before.

I guess I've realised that the increases in performance with astro equipment are incremental and there does seem to be a law of diminishing returns, certainly if you are observing under less than perfect conditions which many of us have to.

As they say though "your mileage may vary"

John

[Ben Ritchie]

I agree with John, for me moving from an 8" to 12" wasn't a "oh wow" change - the extra detail is there and some things that were averted vision objects in my light-polluted garden become directly visible, but it's not dramatic. In fact, the thing I noticed most at first was colour, red giants in open clusters and OIII-green in nebulae stand out in the 12" whereas everything was more monochrome in the 8". However, after a bit of time with it i've certainly come to appreciate the extra light grasp too and it does bring a lot of targets into reach.

One day I like the idea of going to an 18" truss, but not yet

[mdstuart]

I have a 10 inch dob and so far over about 18 months I have logged 50 galaxies and there are potentially another 500 or so I should be able to find so that should take me 18 years....so I would suggest you do not need anything bigger?

[Doc]

As Ben has said the main difference is colour. The colour is nothing like you see in photographs but more colour is apparent the bigger the aperture.

[Chris Stacey]

Thanks John,

As far as light pollution goes I'm pretty lucky, only a few houses in my road and hundreds of acres of farmland behind my back garden. Based on what you, Ben and mdstuart have said I reckon I would be better waiting and making a big jump to a 16" or bigger. It's a major price difference though between say a 12 and 16, another grand on top.

I'll have to see if I can get a look through a few of those sizes before making my mind up - maybe pop to a star party and try some other peoples rigs, gage it from there.

Mdstuart - I am perfectly happy with the 8, I've got years of learning and exploring ahead of me with it. You know what it's like though, I like to have a project I'm saving for in the background - I just can't help it. lol.