4 replies to this topic

[Omniverse]

I'm looking to add a ZWO CAA into my imaging train and I would like to put it before my reducer element. My equipment plan is as follows:

 

1) William Optics GT71 scope with m63 opening

2) m63 to m54 adapter

3) -----------------------------------------------------<<< Insert CAA (m54 scope side to m48 camera side)

4) m48 to m63 adapter

5) William Optics FLAT6Aiii reducer with m63

 

With this plan I'm reducing from 63mm at the scope, down to as small as 48mm exiting the rotator, and back up to 63mm going into the reducer. 63mm > 48mm > 63mm 

 

What worries me now is possible vignetting going into the reducer now. The only thing I have right now is the rotator and I want to know if trying to get the rotator in front of the reducer and risking vignetting is worth it, or if I should go in front of my reducer where the rest of the image train is between m48 to m54 with no current vignetting and deal with taking flats for every change in rotation. 

 

I don't know if that's enough to go on but maybe someone's experience with doing this will shed some light on what I can expect before I spend $200 on adapters. 

 

Finding adapters for this has been a bit tough, especially for m63

Adapters I'm looking at are:

1) William Optics M63(M) to M48(M) Photo Adapter https://davidastro.c...=44967237878045

2) Pegasus Adapter M54 Male to M48 Female https://davidastro.c...=44968076542237

3) William Optics M63 Female to 2" Push-in Adapter for P-FLAT6AIII https://davidastro.c...=44967238304029

 

All of these plus the 16.5mm of the CAA should add a significant bit of length between the scope and the reducer. I'm not sure if that could possibly help? I don't see lengths listed for these adapters so not sure how long they are.

[KGoodwin]

I'm certain you'd vignette your image with that setup.  It would take some math to figure out how much, but I think the answer would be "significantly" given it's an M48 in front of the reducer.  It would be much better to use a larger rotator if you will put it in front of the reducer.  The Pegasus Falcon V2 is M68 on both sides, for example.

[Omniverse]

I'm certain you'd vignette your image with that setup.  It would take some math to figure out how much, but I think the answer would be "significantly" given it's an M48 in front of the reducer.  It would be much better to use a larger rotator if you will put it in front of the reducer.  The Pegasus Falcon V2 is M68 on both sides, for example.

Ya I had a feeling that would be the case. Unfortunately I already have the rotator (didn't consider its placement in front of reducer). I may just use it behind the reducer. My imaging usually involves rotating only once in a night so I should be ok, but may have issues in the future if I need to rotate more. I'll just have to take flats between rotations. 

 

This has been a lesson for me in being stuck in the ZWO ecosystem using an ASIAir. I would have much more options if I didn't use that. 

[KGoodwin]

Ya I had a feeling that would be the case. Unfortunately I already have the rotator (didn't consider its placement in front of reducer). I may just use it behind the reducer. My imaging usually involves rotating only once in a night so I should be ok, but may have issues in the future if I need to rotate more. I'll just have to take flats between rotations. 

 

This has been a lesson for me in being stuck in the ZWO ecosystem using an ASIAir. I would have much more options if I didn't use that. 

If there's no issue with backfocus you definitely want the rotator behind the reducer.  That should not impact how frequently you need flats or whether you need different flats at different rotations.  Is the rotator positioning not repeatable enough to be able to take the flats the next morning by rotating to each location again?

[Omniverse]

If there's no issue with backfocus you definitely want the rotator behind the reducer. That should not impact how frequently you need flats or whether you need different flats at different rotations. Is the rotator positioning not repeatable enough to be able to take the flats the next morning by rotating to each location again?

I will definitely be able to reproduce the rotations at a later date so no issues there. My thought process was just purely based on the thought that I should be rotating the reducer optical elements along with the camera to avoid issues with dust in different positions.