More GSO RC8 Reflection Tests

[dugnsuz (Doug)]

Hello all,
Clear skies last night, so I decided to test various configurations to try and lose the reflections obtained on the M42 image posted previously...
http://www.iceinspace.com.au/forum/a...e.php?a=105044

Reflections in the test images aren't as marked as those in the above link but are there - look just above the Running Man Nebula.

Imaging train configurations detailed below (no LPS filter used)

From L to R:
Image 1 - Baader 7.5mm Spacer > Camera Adapter > AP 0.67x Reducer
Image 2 - Camera Adapter > AP 0.67x Reducer
Image 3 - No Reducer

Image 1's thumbnail shows obvious vignetting with the spacer/reducer combo and strange little reflection above the running man's head.

With the Baader spacer removed in Image 2, the vignetting is reduced and running man's halo is gone - promising!? Still looks like there's a thin reflection on the right hand side though.

Image 3 with no reducer (FL=1624mm) has no reflections but image is soft - ? collimation issue.

Comments/ Advice appreciated

Cheers
Doug

[Paul Haese]

Looks like it is still there despite the absence of the reducer. Time to go hunting around for the reflection.

1. point to a bright star and just put it outside the field to reproduce the reflection. Then remove the camera and look up through the optical path to see where the reflection is located.

2. Do the above with and without the light pollution filter. This might be causing the issue.

3. If the LPF is the cause buy another screw in version rather than one so close to the sensor.

4. If it is the baffle (not likely) then time for the flocking.

Get back to us again, when you have eliminated a few more things.

[suma126 (Shane)]

just wondering what camera are you useing with the re juicer. is there any rejuicer released yet for a dslr and gso rc8

[dugnsuz (Doug)]

Hi Paul - just to be clear Image No.3 is the one on which no reducer was used. I didn't see any obvious reflections initially but your comments made me look harder! I still can't see obvious reflections - could you describe where they are? Perhaps it's my crappy monitor at work?

[dugnsuz (Doug)]

Originally Posted by suma126

just wondering what camera are you useing with the re juicer. is there any rejuicer released yet for a dslr and gso rc8

Don't know if there is Shane - this is expensive trial and error work based on internet forum hearsay!!
I'm using a cooled Canon 40D.

[suma126 (Shane)]

thanks let me know how you go im very interest in this cheers

[strongmanmike (Michael)]

Originally Posted by dugnsuz

Hi Paul - just to be clear Image No.3 is the one on which no reducer was used. I didn't see any obvious reflections initially but your comments made me look harder! I still can't see obvious reflections - could you describe where they are? Perhaps it's my crappy monitor at work?

Its in the lower right corner, faint though.

Mike

[dugnsuz (Doug)]

Originally Posted by strongmanmike

Its in the lower right corner, faint though.

Mike

Thanks Mike - still too faint to see on my work monitor. I'll stretch the original image when I get home to bring it out.
Doug

[mill (Martin)]

Doug the reflection is in all three images at exactly the same spot and crosses thru the exact same star every time.
It is a pity that the weather is not going to be good here tonight or else i could check it on mine.
Martin.

[Paul Haese]

The guys have hit the nail on the head.

I have done a quick highlight to show you what is going on.

[mill (Martin)]

I found some 30 second exposures LRGB with my GSO RC8 from a couple of days ago.
This is without a flattener or focal reducer and stretched to the maximum for 30 sec pictures.
I didn't find any reflections here so it looks like it is from something else than the scope.

[bmitchell82 (Brendan)]

I was under the impression that they had fixed the baffel tube issue just after it was released.

[mill (Martin)]

Yes Brendan they made small ribs in the tubes but when you look thru them it is still a bit shiny.
So that might be a problem still.
I have to wait till Tuesday night for some test of my own to look for reflections.

[dugnsuz (Doug)]

Thanks all for all the input to this thread - I'm starting to get confused though!! As the reflections don't occur in Martin's scope, is my reflection a problem with my baffle - Interesting to see the same reflection at the same position in images with and without the reducer...back to flocking the baffle?
Do the small ribs on GSO's new baffle cause a problem to apply flocking paper?

Or, are reflections just a problem we have to live with in the particular optical system we choose?

Cheers
Doug

[Tandum (Robin)]

Pull out the LP filter doug. Start with a clear path and work up. I get no reflections in mine

Also get the eggy stars under control, it looks like flex to me by the direction they all point.

[mill (Martin)]

And as Paul suggested, go to a bright star and keep it just out of view and see if you have those reflections when looking in the scope without a camera in it.
In my scope the paint isn't perfectly flat black but a bit shiny, but that is only in the tubes and not in the main tube.

[Tandum (Robin)]

I doubt anyone would see the source of the reflection shown in image 3 by looking up the tube if it's that dim in a stacked image.

[mill (Martin)]

Robin i see shiny parts when i look thru the scope in daylight so it might be Doug's problem.
And checking if it is so won't hurt and only will take out guesswork.

[Tandum (Robin)]

But you just posted an image saying/showing you don't get reflections ?
So you are saying, I see shiny bits but don't get reflections?

What I'm saying is strip back to a clear path, he still has a clip in filter in there, fix the flex/colimation then add bits to see what is reflective. And the horse is a better target.

[mill (Martin)]

Yes that is the whole exercise, taking out all the filters and work from that.
Here is the horse i did a couple of day's ago and there are no reflections at all even tough i have shiny bits in the tube.
I know it could be the LP filter.