Gso rc8 + 11002

[Tandum (Robin)]

My first look at the RC8 with the big sensor jammed down it's 2" throat where pretty rank. My T-threaded OAG got in the way badly and had to go plus CCD Inspector was showing almost 80% curvature on the subs so there where lots of comets around the edges.

I got a guide scope on top so got rid of the OAG and borrowed an Astrotech 2" Flattener. The flattener ends at a t-thread but flats seem to fix it up pretty well. The curve is down from 80% to under 40%. I'm seeing some flex out of the guide scope but I was expecting that. Also I am seeing flares in a lot of these test shots which I've never seen before so there may be an issue there as well. There is one in this shot, top left quarter.

Next on the list is to replace the droopy focuser and then a tweek of the mirrors but it looks to be sort of working.

This is RGB only, about 4 each, 60sec subs, really just slapped together for a look.

[OneCosmos (Chris)]

Hey Robin, I think that's a great image - really. I always find globulars quite difficult to process in to an attractive result - and you certainly nailed this one

[RickS (Rick)]

Robin,

Looking much better!

It would be great if you could figure this all out so it will be easy for me when I move to a big sensor on the RC10

Cheers,
Rick.

[Tandum (Robin)]

Cheers Chris, only 15minutes of data, really looking for bent stars

Rick, don't you have one of these? You've got 91.5mm back focus to play with on that thing. Do you know distance to sensor on the sbig with all the bells and whistles?

[RickS (Rick)]

Originally Posted by Tandum

Rick, don't you have one of these? You've got 91.5mm back focus to play with on that thing. Do you know distance to sensor on the sbig with all the bells and whistles?

I do have one of those flatteners, Robin. I haven't worked out all the distances and adapters yet. It's surprising how quickly you can chew up 91.5mm!

[naskies (Dave)]

Very nice! I've yet to try out my RC8 on DSOs using my full-frame SLR. Are you happy with the Astrotech flattener?

[Tandum (Robin)]

Originally Posted by naskies

Very nice! I've yet to try out my RC8 on DSOs using my full-frame SLR. Are you happy with the Astrotech flattener?

The extreme corners have distorted stars, Bottom Left and Right attached. I'm not sure if this is collimation, focuser or flattener or all of the above. I'm not brave enough to fiddle with the mirrors until I know the focuser is square but I would assume if the stars are distorted, they should be equally distorted around the whole image. Another focuser won't be happening till after tax time though, I need to inject some cash into cutting my tax bill

I added an image without flats and exaggerated to show the image circle.

[naskies (Dave)]

Thanks for posting those, Robin. Hmmm... I'll be very interested to see where your investigations take you.