Wedges - worth it?

[animaal]

I have a Celestron CPC800, and I've been very happy with it for visual use and for planetary imaging. For DSOs, I'm considering getting a Celestron HD Wedge Pro, but I've read here that it probably won't be as good as a GEM.

So if I was to buy a GEM setup instead, can anybody advise me what kind of kind of equipment would I need in order to get better results than my CPC800/wedge? I'm guessing it would be far more costly than the wedge, but I'd like to know for sure before proceeding. Thanks.
 

[brantuk]

Imho the only real difference is in the setting up. It just takes a little longer with a wedge and fork mounts so probably best suited to an obsy rather than an astronomer on the move. But so long as you achieve polar alignment then the actual imaging is no different to imaging with a refractor or newtonian. Of course you'll need a reducer as well to speed up the f-ratio to f-6 (your subs would take too long at f-10), but otherwise it's generally the same as imaging with any f-6 scope on an eq mount.

If you went the EQ route then you'd need at least an AVX or HEQ5 - or preferably an NEQ6 Pro, CGEM, or AZEQ6GT. Loads of folks have imaged successfully with a C8 or C925 on an eq mount. An EQ mount is maybe a more flexible arrangement if you have more than one ota, or if you are travelling (eg star party or club night), and there are the usual scope type differences, but other than that I find it pretty much the same.

[nmoushon]

For DSO imaging you will want at least the HEQ5 if not an EQ6. You can obviously go higher if you want. But you will need more than just a mount to start imaging. Because of the long focal length you will want to get a guiding setup. For long focal lengths the best option is to use an OAG with a guide cam though a ST80 with rings works as well but not as good. You will want the reducer/flattener as well as imaging at F/10 is very very slow. Its doable if you are wanting to image galaxies but if you want to imaging nebula then you want the reducer.

[animaal]

Hmm, those mounts look quite expensive, plus an OTA to go with it. I like the simplicity of the Alt-az for initial setup - especially at meet-ups, where I don't think I'd be doing any major imaging.

I have a 0.7x focal reducer and an OAG (I picked one up cheap, figuring I'd need it anyway), so the wedge looks like it might be the way to go for me. I wan't sure if the wedge would scupper my chances of takling decent images, but it doesn't sound like that would be the case.

Thanks for the advice!
 

[brantuk]

I have the Celestron Wedge and it is a very nicely engineered chunk of metal. The adjustment knobs are big and chunky and it's rock solid - dead easy to adjust and very smooth movement - much better than the older version. It's really just a question of setting it up and getting polar aligned which is no biggie really. You may have to do a drift alignment to get the tracking spot on and an oag is the way to go. But with the 800 just watch your clearance between the base and the camera when pointing at the zenith - the 925 has bags of room but the 800 is pretty tight.

[ollypenrice]

I never had much joy with wedges and would never recommend them for portable astronomers, though I've seen Annie Morris in action here and it can be done - to her remarkable imaging standard. There is a bit more to it than just 'wedge versus GEM.' Long focal lengths require very precise guiding and this does not come 'plug and play' from any sub premium mounts, whether NEQ6 or American forks. It doesn't always come from premium ones either!

It sounds like the screamingly awful old American fork mounts and wedges have raised their game since I last wasted months and a small fortune on them but don't expect it to be dead easy to do deep sky imaging at long focal length on anything. At the risk of being rudely 'off topic' I'd just ask you if you've considered entering the deep sky imaging world at a shorter and far more forgiving focal length. This would be what I'd recommend.

Olly

[kirkster501]

I have used one.  Twice.  It was the biggest PITA ever and left me traumatized enough to sell on immediately and re-evaluate where I was going with AP.  Some make them work though so don't let my ranting put you off.  But it was not for me, and not for many others either.  Far to much faffing around in our fickle UK skies.  But if in a permanent observatory, with an OAG and faint, small galaxies are your thing then it may work for you.

[animaal]

Mixed opinions then. I think I'll try it anyway. I've tried one session taking short exposures without a wedge. The result was far from impressive, but I was chuffed. It looks like decent results are possible, although not easy.

If it turns out to be more trouble than it's worth, I'll take Kirkster's lead, and sell it on.

Thanks.

[kirkster501]

Mixed opinions then. I think I'll try it anyway. I've tried one session taking short exposures without a wedge. The result was far from impressive, but I was chuffed. It looks like decent results are possible, although not easy.

If it turns out to be more trouble than it's worth, I'll take Kirkster's lead, and sell it on.

Thanks.

Yep, just see how you go mate.  Is there any way you can leave it set up when you've got it all aligned?  Throw a tarpaulin over the mount and wedge?

You'll need to check out drift alignment.  And for that you ideally need a East and West view where the scope will be placed.  A PITA and head banging procedure to do when you've finally set up and it clouds over just when you're ready to set the camera going!  Trust me, been there and got the T shirt.  OK it's doable and worth if you're in Arizona and know it will be clear for hours. But in the UK/Ireland?

The wedges are also HEAVY and getting a CPC on top of the wedge is not for the faint hearted and you need to be strong enough to do it alone to remove at three in the morning.

Seriously mate, think about these things and don't just think "sweat the CPC asset". 

[ollypenrice]

I'm grateful to Steve for having used the kind of language I would have used if I were being more honest, but I've upset LX200 devotees in the past and now give only a very muted hint of how deeply I detest their fork and wedge system!

If you go for a wedge I would say, Go for a good one and try for second hand then you won't lose too much when if it doesn't work!    The so called 'Supawedge' was shockingly expensive and consisted of some rough castings, un-machined and with sloppy-fitting bolts. And that's it. When you adjusted one axis the other axis moved. When you did a final tighten on either axis they both moved. When you eased either in order to re adjust, they both moved again. Happy days...

Olly