Cannot get rid of hot pixels

[fbecker65]

Hello.

No matter what I try (Hot Pixel Suppression or Darks) I cannot seem to get rid of these trailing hot pixels. I do not use a Guidescope since the images are only 30 or 60 second frames in my ZWO 533MC Pro at -15 degrees. What am I doing wrong?

[admin]

Hi,

did you try adjusting the 'Hot Pixel Sensitivity' when using the hot pixel removal option? You can do that while watching individual frames (with a stretch) and see what level is required to bring the hot pixels under control - see https://docs.sharpcap.co.uk/4.1/#Hot%2F ... %20Removal

Dark frames should also bring them under control, but make sure that you take enough dark frames and that they are taken at the same sensor temperature as the light frames.

Finally, -15 is probably colder than you need to go for the 533 sensor, modern sensors don't suffer nearly as much from thermal noise as older ones, so the key thing is getting the camera to a constant temperature (maybe -5 or 0C) rather than as cold as possible.

cheers,

Robin

[fbecker65]

Robin,

Thank you for the reply.

I have tried suppression at 2 and 8

I have taken 15 darks at the same temperature and gain.

I will try using the 0 degrees.

[admin]

Hi,

I often use 15 or so as the hot pixel sensitivity threshold. The way to set that value correctly is to set the camera up taking darks at the desired gain and exposure. Then apply a strong display stretch (use the auto stretch button) to see the noise in the image - you may even want to stretch further so you can actually see the hot pixels in the individual dark frames. Once you have got that set up, turn up/down the hot pixel sensitivity until you see a good reduction in the hot pixels.

You will never get rid of all of them mind you - the more you stretch, the more you will see as pixels that are only a bit 'warm' get brightened by the strong stretch.

cheers,

Robin

[fbecker65]

Thank you for the recommendation.

I will let you know how it goes after I figure this out.

[fbecker65]

Robin,

I did as recommended.

You can see that the temperature is at 0 degrees, gain at 100, exposure at 30s.

I have the Hot Pixel Removal at 1 and at 10. I cannot seem to get it higher than 10.

I see no difference.

[AstroChessPilot]

Check your flats and darks to see if those hot pixels are in those images. I had a similar experience with this and new clean flats and darks was the solution. Sometimes it took multiple attempts to get clean flats and darks.

[carlomuccini]

They came to me by setting my 533MC in RGB16
Since I set it to RAW16 they have disappeared with Hot Pixel Removal set to 10

Carlo

[fbecker65]

Thanks to both of you.

I will get new flats and darks

And make sure I am in RAW 16

[carlomuccini]

... let us know ....

Carlo