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Gain and Offset for QHY8L


ianaiken

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Hey all,

OK - so I've been running through the scientific method of determining gain and offset as written here linky

My first go came to the conclusion that for my QHY8L the gain should be 7 and offset 120. This was using my aurora flat panel as a light source, which I think was too bright.

So I did a second test, pointing the camera to the ceiling in a lit room. This gave a conclusion of a gain of 14 and offset of 120.

So I am reasonably confident of the offset, but it's the gain and the varied result I'm getting.

Here is a link to my data in excel > linky

Obviously while it's not good weather for imaging I want to get this sorted so when it is I'm ready and not wasting time with poor subs. I see a lot of people with different gains and offsets, with gain much much lower than this.

Any advice / help / suggestions?

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Hey all,

OK - so I've been running through the scientific method of determining gain and offset as written here linky

My first go came to the conclusion that for my QHY8L the gain should be 7 and offset 120. This was using my aurora flat panel as a light source, which I think was too bright.

So I did a second test, pointing the camera to the ceiling in a lit room. This gave a conclusion of a gain of 14 and offset of 120.

So I am reasonably confident of the offset, but it's the gain and the varied result I'm getting.

Here is a link to my data in excel > linky

Obviously while it's not good weather for imaging I want to get this sorted so when it is I'm ready and not wasting time with poor subs. I see a lot of people with different gains and offsets, with gain much much lower than this.

Any advice / help / suggestions?

I used the same method as you, and used an EL panel but dimmed it down with a few sheets of A4 paper to get longer exposure times.

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Well I just did the test again with flat panel and some A4 and this time I get gain=17 and offset=120

So somewhere between 14 and 17 for gain and offset 120. Madness I am clearly doing something not quite right with these varying results. I would have though ultimately I would be getting the same result each time.

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I have 2 QHY9's - mono and colour, one is set to Gain 22, Offset 100, the other is Gain 25, Offset 110.

I did it once then left it, no doubt if I did it again I would come up with different results.

Like Blinky says its only a ballpark setting, I should imagine that a setting of 10 units either side wouldn't make much difference.

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  • 2 months later...

Ha nice one thanks. I bet this was the telephone cable that goes overhead! I recall that the scope was moving through that area during this session (in fact pretty much anything I image has to pass through the telephone cables.

Many thanks!

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