Author Topic: large stripe on dark frame  (Read 2095 times)

DennisUA

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large stripe on dark frame
« on: April 09, 2009, 02:37:42 PM »
I recently changed driver for QHY8 from Toms to latest QHY. The one with 1024B in the name.
Now I have this strange stripe on the right side of my darks.
Any ideas where they come from and to cure them?

Thanks!



abracad100

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Re: large stripe on dark frame
« Reply #1 on: April 09, 2009, 06:22:05 PM »
hello

That is normal, it is called "overscan area". It could offer a lot of useful information for you.

To learn more of it, just google the "overscan area".

A lot of DSLR user don't know what it is, so never stay on the knowledge of DSLR, learn more about the true CCD.

best regards


QiuHY

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Re: large stripe on dark frame
« Reply #2 on: April 09, 2009, 08:03:20 PM »
Yes this is the overscan area. With this area you can do more things:

1. Use it to get the bias level value and the readout noise. 
2. Use it to get best offset value
3. Use it to correct the horizonal bias shift  if there is such noise exsit (Need some software to support it)
4. The new fireware make USB pause only happens in the overscan area. It will not affect image any more.
and there is some more application with this help of the overscan area.

Best regards,

DennisUA

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Re: large stripe on dark frame
« Reply #3 on: April 10, 2009, 01:14:29 AM »
Thanks Qui, abracad!
I wonder if it is possible to automatically crop those ares for regular preprocessing-aligning-averaging?

QiuHY

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Re: large stripe on dark frame
« Reply #4 on: April 10, 2009, 08:16:47 AM »
Hello,
        The crop is very easy to be done in software. I will consider to add a function for it later. But for process the area is not effect anything. You can crop it after stacking .  Tom's software has crop this part yet. If you like the image auto cropped you can use Tom's software/drivers.


Best regards,
« Last Edit: April 13, 2009, 08:19:35 PM by QiuHY »