QHY8L - Calibration Frames ! ! !

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QHY8L - Calibration Frames ! ! !

Postby pscammp » Wed Mar 23, 2016 7:49 pm

Hello All,
Got to ask this as it's driving me mad !

I have a QHY8L which has a Skywatcher coma corrector on an extension tube and an IDAS P2 LP filter
on the very front which is in a 10" newt @ F4. I am having problems with, I assume, calibration frames
which I see on the net...I'm not the only one !

I have x10 Bias, x10 Flats (incorrect Angle) and x10 Darks

I only managed to save x10 Lights as due to a problem I lost the other 20 of them, the following is what
I get when processing them in Pixinsight using the BatchPreprocessor script and loading the resulting
image for a stretch with the STF tool -

Integration.jpg


Obviously I have overexposed corners and also a large area to the left over bright also. Unfortunately, the
Flats were taken at a camera angle of zero degrees the following day but the Lights were exposed at an
angle of 99.1 degree's on the scope during the imaging session itself. I lost the original Flats when I lost the
x20 Light frames. I redone some Flats at the correct angle and it sorted out some of the inner glow to the
left but still left me with over exposed corners.

The Flats used in the above image are at 22000 ADU, I also done a library of x10 Flats each with ADU's ranging
from 9000 ADU all the way to 32000 ADU in 3000 ADU increments but the corner glow is identical in all the tests
I did, so this is driving me mad as all was fine and simple with my old EOS 1000D.

I see from trawling the net that some say to do Flats above 4 sec's with a QHY8L and others say do them short
like you would with a Canon - No difference, still corners overcompensated. Also Bias vs Dark Flats - No Difference
same corner glow.

Im loading up a Bias, Flat, Dark and Light frame in case anyone can see where the problem may reside:

https://dl.dropboxusercontent.com/u/493 ... C_0001.fit

https://dl.dropboxusercontent.com/u/493 ... C_0002.fit

https://dl.dropboxusercontent.com/u/493 ... C_0002.fit

https://dl.dropboxusercontent.com/u/493 ... C_0018.fit

The Flat above is a 22000 ADU (used in the pic at the top) at an exposure time of 14 sec based on the advice I read
on Stargazers Lounge to get it above the 4 sec mark. I had my EL light panel with x6 sheets of white paper in front
which allowed me to build the FLAT library of Flats between 9000 and 32000 ADU ranging with exp times of 4 secs
to 20.1 sec's.

The center of illumination in the images were quite off center due to my focuser being not lined up correctly with
the imaging train which I have since corrected in case anyone spots that in the Light and Flat.

So......

With Gain and Offset set at 10 and 117 and image acquisition being performed by SG Pro and stacking in Pixinsight.....

Does anyone know where im going wrong, why the corner glow at all ADU options ?? Maybe the Flats are not the problem ! !

Do my FLATS and BIAS frames really have to be above the 3.65'ish sec's to ensure they are not exposed within the dual
readout mode of the camera ??

Can anyone actually fully agree on exactly how Flats and Bias (or Dark Flats) frames should be captured and processed
with the 8L ??

HELP !!!

Many Regards and thanks in advance for any help
Paul

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Re: QHY8L - Calibration Frames ! ! !

Postby julianr » Wed Mar 23, 2016 8:00 pm

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Re: QHY8L - Calibration Frames ! ! !

Postby craig a » Wed Mar 23, 2016 8:21 pm

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Re: QHY8L - Calibration Frames ! ! !

Postby julianr » Thu Mar 24, 2016 1:41 am

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Re: QHY8L - Calibration Frames ! ! !

Postby julianr » Thu Mar 24, 2016 1:43 am

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Re: QHY8L - Calibration Frames ! ! !

Postby pscammp » Thu Mar 24, 2016 6:08 pm

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Re: QHY8L - Calibration Frames ! ! !

Postby pscammp » Thu Mar 24, 2016 6:31 pm

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Re: QHY8L - Calibration Frames ! ! !

Postby julianr » Fri Mar 25, 2016 2:22 am

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Re: QHY8L - Calibration Frames ! ! !

Postby pscammp » Fri Mar 25, 2016 7:04 pm

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Re: QHY8L - Calibration Frames ! ! !

Postby carastro » Fri Mar 25, 2016 9:19 pm

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