Question on Super-Bias

[Lammertus]

Hi all,

I've been trying to make a super-bias but once the Bias-frames are integrated
and I do the super-bias process, the result is a vertical banded image, whereas
the integrated bias frames look rather uniform.

The camera I used for this try is ASI224MC and the imaging program APT.
Camera setup to do 200 bias frames of 0.001 second each with 1 second
wait time in between.

What am I missing or doing wrong with the super-bias??
Edit: I forgot to mention that I did not debayer the frames.

[msmythers]

The vertical banding is correct. That is the actual structure of the bias pattern. You should look at this posting if you haven't already. http://pixinsight.com/forum/index.php?topic=7266.0


Mike

[Lammertus]

Hello Mike,
Thank you for pointing me to that link, which as a matter of fact, I already
went through eventhough still with a lot of questions.

For example how to adjust to 16bit STF, if I do a screentransfer and stretch
with the same parameters the maser-bias and the master-dark things look
rather smooth.
After just clicking super-bias, I obtain a vertical banded image with which
likely I won't obtain any benefit.

How do I adjust to 16 bit's in order to get this smooth looking super-bias???


Sorry to ask soo many things, I'm just a beginner and have many things
to go through!

Best regards,
Mert

[TobiasLindemann]

Mert,
as Mike said, the vertical stripes are correct. They are also visible in your masterbias, but are predominated by the noise.

16bit STF is standard, if you want to change to 24bit STF you have to click on the 24 in the upper right section (see image). With the superbias applied you see very small steps in your image, because it is so smooth. So 16bit is not enough to display these steps and you have to change to 24bit. But this changes only how the image is displayed and not the image itself. The superbias is already correct as it is.

Greetings
Tobias

[Lammertus]

Ah now I see, thanks a lot for pointing that out to me!
As a matter of fact I just reintegrated the darks into 1 master-dark
then integrated the Bias frames and did the SuerBias process.
After that I subtracted the suoerBias image from the Masterdark and
effectively the result is smooth!

Again, thanks a lot to all!!
Mert