Noise in Image?

gordonewen

I use my 120MM for solar imaging and usually get very good results. However, in the last few weeks I have noticed I am getting a vertical noise pattern in my images - see the photo attached, you will see it best if you zoom in on the image. The capture info is below:

ROI=1280x960

FPS (avg.)=16

Shutter=0.405ms

Gain=13

USBTraffic=53

AutoExposure=off

Brightness=0

Gamma=41

Histogramm(min)=2

Histogramm(max)=196

Histogramm=76%

Noise(avg.deviation)=10.08

Limit=1200 Frames

Sensor temperature=25.0 °C / 77.0 °F

Can anyone advise on the origin of this noise and how I can get rid of it?

I shot a video of the sky (defocussed so no detail) under the same exposure settings and processed it with a lot of stretch on the image and got the second photo attached. Is this the origin?

I note that so far I haven't seen this with video recorded at 2.26ms exposure.

Any advice appreciated.

Gordon

Sam@ZWO

Hi Gordon

this usually happen when change gain from a very big value to a very small one

just like in your case.

there is a column noise correction of the sensor, and different gain have slightly different column noise.

so you'd better start FC at a relative resonale gain. then you won't see these vertical noise

we will try to improve our driver too make this column noise correction more smart

gordonewen

Sam, thanks for the feedback.

Gordon

jcarels

Is this the same problem and how do I avoid it. Debayer was on GR and bilineair. At first I could see the debayer pattern on the screen in firecapture (debayer was on). Then I changed exposure and gain and the pattern seemed to disappear.

I didn't change the settings since the last time I took (good) images.