The problem with the light and the focuser (Michael Timm)

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The problem with the light and the focuser

I have a serious problem with the crayford focuser and light injection. Picture A) shows the problem: This is a stacked picture of 80 frames with 120 secs each. The background shouldnt be so light. I have tracked the problem down. In picture D) you can see where the light enters the system.

The problem is very massive. If i put the system out by cloudy daylight (no sun exposure) and expose 1 sec with gain 256 the picture is nearly pure white (same with 15 secs and gain 0 -> see picture C for an example). Really a lot of light enters the focuser. If i put a dark cloth over the focuser the picture is black. I verified the light-entry-points with a flashlight.

I need some sort of cover for the end part of the focuser. I will track the steps i take to a solution here. Maybe this helps if someone suffers from a similar problem.

In E) you can see the first approach to a solution: My lovely wife made me some sort of a... ehm... condom. It is way better than before, but not perfect. I think some sort of bag will do the job.

F) is an image under nearly the same conditions like C). Daylight, clear sky, no direct sun exposure. Way better!

Original
D
E
F
Final
G

D

Description: The part where the light enters the system.

Uploaded: ...

E

Description: Version 1.0: The Condom.

Uploaded: ...

F

Description: Single shot with condom, 15secs, gain 0.

Uploaded: ...

G

Description: Light entering through the extension of the OAG.

Uploaded: ...

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The problem with the light and the focuser

The problem with the light and the focuser

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