ASI294MM Pro speckle problem

andrew s

I have been testing my camera using TSX with all the latest software. I find the occasionally I get speckle noise near the centre of the frame. See attached. Any advice would be most welcome.
Regards Andrew

andrew s

Better images

andrew s

I should have said its intermittent attached it's ok but I can't find a consistent way to cause or cure it.

w7ay

@andrew s#58299 I find the occasionally I get speckle noise near the centre of the frame.

Try running the camera without turning on the cooler, and if the speckles are consistently absent, then it is very likely to be caused by ice (ice tends to form near the center of the sensor).

If the cooler has nothing to do with the speckles, the problem is elsewhere.

Chen

andrew s

Thanks but I don't think it's ice. This is being run on a test rig inside and it's very dry here. In addition it just goes without turning off the cooler. I will look at the sensor to check if water is somehow trapped in the body of the camera.

Regards Andrew

andrew s

I have now tried the following. I took a series for flats from 25 to -5 c and the images were normal until -5 c when the speckles appeared. I then returned the camera to 0 c and the pattern was normal with no speckles. I then went down in 2 degree increments from 0 to -10 and the pattern was normal with no speckles so if it is moisture it is behaving very strangely. On further cooling to -15 c the speckles did not return. Regards Andrew

Tech@ZWO

@andrew s#58309 Could you send us a fit file for analysis?
It looks like dew problem.
Usually we recommend slowly cooling the camera to solve the problem, which like the way you tried.
Before letting it cool down to target cooling temp, please keep it at 5℃ for 5 minutes, then cool it down to target temp and if this continues to appear, it will basically disappear in 5-6 minutes.

andrew s

Here is a crop of a 2x2 Frame. Thanks for your advice it seems to work. Thanks Andrew

andrew s

Sorry up load fits shows in reply when I edit but does not seem to be included in post.

Tech@ZWO

@andrew s#58396 Yep, i didn't see that.