Imaging Scope Changes

[adamsp123]

I am after a some advice regarding the possibility of changing my Imaging scopes.

I am quite keen to image smaller DSOs, especially Galaxies, but I feel I need a scope of greater focal length that those I possess to increase the image size. On top of that I am considering to compliment a long focal length scope by adding a short focal length refractor as well in the mix.

Thus I am looking for some advice on potential candidates for both scopes.

My mount, since I have upgraded it to Nexatlux (modded Vixen Atlux), behaves very well and is quite capable of handling quite heavy loads.

I was wondering if an 200-250mm RC or similar folded optics solution would be a good choice or a large F5 Newtonian, although I would prefer an already optically corrected design of scope so I just bolt on the camera without further corrective optics.

The choice for a short focal refractor seems to lead me towards the TS 65 Apo with corrector lens included, although I have seen some early reports of problems with these I have also heard that they are now of good quality.

I don't want to spend too much money, so Takahashis etc are out, but any advice on either chioce,and I would consider 2nd hand, would be gratefully appreciated.

cheers Pete

[andrew s]

Pete - Have you thought about using something like a Powermate to increase the FL of your existing scopes rather than buy a new one? Not as much fun but could save some money. Andrew

[Tinker1947]

Galaxies are mostly faint and distant, so you need as much light and a decent focal length, a Newtonian (12") on a good mount, a NEQ6 won't cut it if your imagine with a 12" something like a CGem DX....its not a cheap hobby.......

http://www.firstlightoptics.com/celestron-mounts/celestron-cgem-dx-goto.html

[adamsp123]

Andrew, never thought of that idea, so I will investigate.

Tinker, a 12 inch Newt was a scope I would consider as it would be relatively cheap and my Atlux mount should handle easily but I am somewhat put off by the size ie physical length versus a folded optical design, but not ruled out.

[Luke]

One thing to keep in mind with using a powermate is that it will slow down your telescope. So I guess your Mak Newt with a 2x powermate would be F10.6. I guess that's more usable than my F7.5 scope - at F15 it would be no-go for galaxies for me with my DSLR at that speed.

I do use the powermate with the F7.5 scope for the moon sometimes and I'm planning to try some of the brighter DSOs with it.

[ollypenrice]

Barlows and Powermates are pretty much out of the question for DS other than on the odd bright PN. Too slow. The Atlux is a big mount but is it accurate? You need accuracy at long FLs. I'd certainly use an OAG.

If it is then the RCs are pretty good though the basic versions are not mechanically perfect which is why several places, including Ian King, are working on new OTAs for the original optics. There are the Edge series but they are slow at native and I think the image circle is small with the only reducers available. Something to check. The Meade ACFs work with the AP reducer and give decent results. I'm surprised they are not more popular.

Olly

[adamsp123]

Luke and Olly, Thanks for your input, it is true I wouldn't want to "slow" the scope down more than necessary.

Interesting about the RCs and as far as the mount goes it tracks very well now I have ditched the starbook (and its DEC bounces) for the NexAtlux controller, handles the heavy 190MN plus other bits easily.

I am slowly leaning towards a 300mm F5-ish Newt, I already have a coma corrector if I need one plus they are relatively cheap but I will keep other scope designs in mind.

[Sp@ce_d]

I know it's slightly off topic but doesn't sensor/pixel size also come into play here? For instance would dropping down from the 383 to the 314 also go some way for the scales/FOV involved?

[andrew s]

Pete - a 300mm F5 Newt is a good choice (I have one) but I would look at the size of the DSO you want to image and see if it will show any detail at the image scale of the 300 F5. One of the reason I mentioned Powermates is that the image scale needed to see small galaxies if difficult to provide without some amplification either by a secondary mirror (SCT or RC) or via a Powermate or Barlow . This is one of the reason large RCs or SCTs are used for small galaxies even though they are quite "slow" when compared to say wide field APOs.

Regards Andrew

[adamsp123]

What I would hope with a scope of suitable focal length is being able to 2X bin the data on my 383L+ and still get an usable arcsec/pixel.

Objects I would look at imaging with a long FL scope would be the likes of M51, M1, M27, M57 and many of the "larger" NGC galaxies.

As far as a widefield scope I would like some ideas if anyone uses one.

[Sp@ce_d]

What about finding a second hand WO ZS66 apo? I picked one up a few months back, haven't found a reducer yet but the GT81 flattener works well with it.

Here's a couple taken with the 1000D so you get an idea of FOV.. ( edges cropped off to clean up)

[adamsp123]

What about finding a second hand WO ZS66 apo? I picked one up a few months back, haven't found a reducer yet but the GT81 flattener works well with it.

Here's a couple taken with the 1000D so you get an idea of FOV.. ( edges cropped off to clean up)

The pics look good and show the sort of wide angle view I would like - so that scope will go on the potential list.

[adamsp123]

Just posting an update - I have just found out from Martin at FLO that the Skywatcher 300P newtonian OTA weighs a massive 25Kg or there abouts.

That has rather dented my idea of maybe moving to this scope for imaging, the OO scopes seem to be much lighter but more expensive and also I have some doubts about their quality/service as some people have posted negative feedback on some forums.

Oh well keep on looking