8" - SCT vs Reflector vs 80mm frac

[iapa]

8" SCT, 2032mm fl (f10) vs 8", 1000m fl (f5), vs ED80, 600mm fl  (f7.5)

These will be set up (calcs are rounded for f-ratios):

• SCT with 0.63 focal reducer/field flattener (fr/ff)= 1280mm fl, f6.3
• Newt with 0.9 coma corrector (cc) = 900mm, f4.5
• Frac with field flattener (ff) = 600mm, f7.5

Currently primary use is imaging (DSOs primarily, I do very little planetary) with APC sized DSLRs using 2" adapters etc. until the adapter for the camera which will be whatever is suitable for each ff/fr/cr lenses e.g. M48 for the 0.63 fr.

These will be used on either CGEM-DX or AVX mounts with either Orion 50mm 162mm fl or 80mm 400mm fl guide scopes

Which should I get rid of (I am ignoring the fact that the newt is damaged - if the vote is to keep newt I'll get a replacement) as these are taking significant amounts of space in the house now

 

[Tim]

Short answer? The Newt.

Long Answer. The Newt. It is occupying the most space, is the hardest to collimate, dews up the easiest, requires a guidescope or OAG and isn't easy to get an OAG to fit in front of the camera, and it is broken.

If you lose the SCT you lose your planetary and lunar views, and although you say DSO imaging, what about small objects like M76, The Cats Eye, the Eskimo, The Blue Snowball, M97, M57, M1, most of the M's, and a whole sky full of planetary nebulae.

If you lose the Newt you aren't going to miss it on those objects. 

By keeping the refractor and SCT you could also lose the two guidescopes and get the OAG with the money, thus saving you even more room. 

In an ideal world keep all three and just lose the guidescopes. Unless you plan to image the upcoming comets by tracking on the comets, in which case an OAG wont help you.

For me the purest pleasure when imaging comes from using my refractors, simple, sharp, just get on with it.

Tough choice you have to make.......

[ecuador]

I had the same scopes. First I got the newt (200PDS), and if I only wanted one scope I would probably be happy with that one, but I was missing some wide fields, so I got the 80ED and then I also got a C8 for even longer focal length, a little better planets and more portability, and eventually I stopped using the newtonian. I left the newtonian at the Summer home where it is the only OTA (as I said it is a fine all-around instrument).

So, keep the 80ED and the C8 is the suggestion. I personally did not stay there. E.g. a reducer for the 80ED will give you one more focal length to "play" at. I also upgraded from the C8 to C9.25 (a good deal just happened - that was not planed) and I found out it works better with the reducer (less vignetting on my DSLR) and the ~1450 focal length is an even better complement to the 600mm of the 80ED.

Edited December 20, 2016 by ecuador

[iapa]

14 hours ago, Tim said:

Short answer? The Newt.

Long Answer. The Newt. It is occupying the most space, is the hardest to collimate, dews up the easiest, requires a guidescope or OAG and isn't easy to get an OAG to fit in front of the camera, and it is broken.

If you lose the SCT you lose your planetary and lunar views, and although you say DSO imaging, what about small objects like M76, The Cats Eye, the Eskimo, The Blue Snowball, M97, M57, M1, most of the M's, and a whole sky full of planetary nebulae.

If you lose the Newt you aren't going to miss it on those objects. 

By keeping the refractor and SCT you could also lose the two guidescopes and get the OAG with the money, thus saving you even more room. 

In an ideal world keep all three and just lose the guidescopes. Unless you plan to image the upcoming comets by tracking on the comets, in which case an OAG wont help you.

For me the purest pleasure when imaging comes from using my refractors, simple, sharp, just get on with it.

Tough choice you have to make.......

I didn't find collimation too much of an issue on the newt  - just watched a few videos for collimating the SCT and that looks scary

Dew strips on all three have minimised that issue - when I remember to use them (forgot on Sat night and the SCT corrector froze over).

Have an OAG - just sorting extension tubes to get the right spacing to the sensor. If I didn't given it's half the costs of replacing the 200PDS....

Damn - I think I have covered all of your points

 

 

[ecuador]

1 minute ago, iapa said:

I didn't find collimation too much of an issue on the newt  - just watched a few videos for collimating the SCT and that looks scary

Collimation is easy if you use a planetary/guiding cam and the program Metaguide.

[iapa]

14 hours ago, ecuador said:

I had the same scopes. First I got the newt (200PDS), and if I only wanted one scope I would probably be happy with that one, but I was missing some wide fields, so I got the 80ED and then I also got a C8 for even longer focal length, a little better planets and more portability, and eventually I stopped using the newtonian. I left the newtonian at the Summer home where it is the only OTA (as I said it is a fine all-around instrument).

So, keep the 80ED and the C8 is the suggestion. I personally did not stay there. E.g. a reducer for the 80ED will give you one more focal length to "play" at. I also upgraded from the C8 to C9.25 (a good deal just happened - that was not planed) and I found out it works better with the reducer (less vignetting on my DSLR) and the ~1450 focal length is an even better complement to the 600mm of the 80ED.

I chose a different route - 200PDS was second reflector, then a C8 came up at a good deal. The refractor was my replacement for the 200PDS when it bounced off the ground (hence broken).

I've got the FF for the ED80 already. A reducer for the Ed80 sounds interesting - bring it down to f6.3, same speed as the SCT with the reducer. May be good to get different fov images of the same target at the same time

[ecuador]

1 minute ago, iapa said:

I've got the FF for the ED80 already. A reducer for the Ed80 sounds interesting - bring it down to f6.3, same speed as the SCT with the reducer. May be good to get different fov images of the same target at the same time

If you wait a few days (until it clears out) I can tell you how the £75 Altair 0.8x reducer compares to the TRF-2008 on the 80ED, since I have both. They are supposed to take it down to f/6

[iapa]

Waiting is good - while someone else does the comparisions 

 

[ecuador]

On 12/21/2016 at 11:02, iapa said:

Waiting is good - while someone else does the comparisions 

 

Turns out that the Altair Lightwave works very well with the Evostar 80ED, see my review here!

Edited January 11, 2017 by ecuador