No result using Flats

@rkottink Hi Rob. Have you been using the flat panel in combination with the ZWO DualBand filter before? If yes, I suppose you got good results?

Wouter

@wvreeven Hi Wouter, yes, i've done this all the time. With good results. It seems like i began using APP 1.083.2 i've got some strange results. Sometimes i could work around it or i just used the crop tool.

Anyway, looking at the image and the calibrated image, i can't see any difference.

Kind regards, Rob

@rkottink Can you post a screenshot of the histogram of a single flat?

@wvreeven

Hi Rob @rkottink,

What kind of frames are you using to calibrate the lights? Only flats? Or also bias and/or darks and/or darkflats?

Did you check that all frames for calibration are compatible with your lights? Same sensor gain and offset?

What does APP show in the frame list panel when you apply the masters to the lights ? Are all masters that are created/loaded attached properly to the lights in the frame column?

Mabula

Hello Mabula @mabula-admin,

I'm always using flat frames (masterflats) and Bias frames (Masterbias). 

I was also thinking that maybe the offset was not correct. Normally for the ASI533MC PRO the offset of 17 works fine.

I saw that the offset somehow changed to 83 (way to high).

The light frame had an offset off 83 and the flats of 17.

I took new flats the day afterwards with an offset of 83.

But the results where the same

Below the fits header containing the gain and offset of a light frame and a flat frame

I also checked  the frame tab, all subs are assigned with MB and MF.

Previously i always choose for loading the Lights, flats with default "apply "FILTER" header tag or assign Mono/RGB.

That gives now these strange results.

When i load the lights as default, and the choose for the flats: "All channels" , it also give these strange results.

When i load the lights as default, and choose HA and OIII channels then it seems that there is no difference between the image/lineair and calibrated.

EDIT:I just tested the last scenario. It seems that the MB is assigned, but when i choose for the master flat HA and OIII at the same time is doesn't assign the MF. It also doesn't show in the frame tab.

Kind regards, Rob

Hello Wouter @wvreeven; Hello Mabula @mabula-admin,

I found out that the culprit is the difference in the offset of the Flats compared to the offset of the Lights.

Through some changes in the rig setup, not be able to set the offset in ASI AIR PRO, and using previous flats with another offset led to the strange results.

Also the ascom provided me with a different offset  then what Asi Air by default sets for the lights .

Add the fact that during a session i changed the offset for the lights, it got really complicated.

Below the images of 1 session where the sequential subs have a different offset (Offset 83 vs Offset 17) and the Flats all had an offset of 17. The calibration is the really messed up.

It took a while before i noticed this ( 😳 )

Anyway, i'm glad that i found what the culprit was.

Sorry for any inconvenience and time you put into this case.

Kind regards,

Rob Kottink

Hi Rob @rkottink,

Excellent, thank you for letting us know that you found the cause of the problem 😉

Yes, when you change capture software or hardware or even update the capture software or firmware of the capture hardware, these issues are quite common unfortunately... so as a rule of thumb: if you change the software or software version or change the hardware, always make a new calibration frames with the new setup with same settings as the lights. It can prevent many issues and unexpected results 😉

Mabula