Horizontal lines in Flats

[OJ87]

Hi Every one, 

i'm just starting with my mono astrophotographie, today i tried to take Flats using my LCD Flat-Lamp. My cam is ASI 1600mm. i'm tried to get ADU arount 23k , but as i get close to it it showes horzontal lines , Exposure lenth about 0,01293sec. is it normal? Gain was 0 and Offset 50.  i tried to find it out in Internet, but not body mention it. i would be happy for any suggetions. Thanks

[Laurin Dave]

I think the exposure is too short for the camera to operate stably Try dimming the light source with some writing paper or a white tee shirt so that you get an exposure time for your flats longer than 0.1 seconds.. and use matched flat darks to calibrate.  I take the camera off the scope to do darks to make sure there are no light leaks 

[OJ87]

1 hour ago, Laurin Dave said:

I think the exposure is too short for the camera to operate stably Try dimming the light source with some writing paper or a white tee shirt so that you get an exposure time for your flats longer than 0.1 seconds.. and use matched flat darks to calibrate.  I take the camera off the scope to do darks to make sure there are no light leaks 

Thank you, i will give it a try.

best regards

[old_eyes]

On 29/03/2020 at 08:42, Laurin Dave said:

I think the exposure is too short for the camera to operate stably Try dimming the light source with some writing paper or a white tee shirt so that you get an exposure time for your flats longer than 0.1 seconds.. and use matched flat darks to calibrate.  I take the camera off the scope to do darks to make sure there are no light leaks 

My QHY168C definitely did not like very short flat exposures. I now go for a couple of seconds. I also found that the camera was fussy about USB connection with short exposures, so I no longer use a hub and run a cable direct from camera to imaging computer USB3 input.