Help in identifying flat/image issue

[rustigsmed (Russell)]

Hi all,

i am wondering if anyone can help out with this issue.
Appears to be in all my flats on a variety of filters (and might be in my lights too - just a bit) - centre zone of image, ending up with black speckling or noise? Fog / frosting / dirty flat panel?

crops of individual flat (with magnifier in DSS v5) / and individual light.

Thanks

Rusty

[rustigsmed (Russell)]

Ok have looked at some more subs this time on different nights (night 1 no specks) night 2 - specks. Scope /camera stayed out and wasn't moved. unfortunately i didnt get flats first night.

[bojan]

Fingerprint?

[Dennis]

Hi Russell

I once saw something similar when I was viewing a Flat in The Sky X Pro Camera Control Module and I had the Histogram set to a funky stretch from playing around with a recent image.

When I re-set the default Histogram stretch, the flat appeared normal as per my other Flats.

It seems that my funky manual settings somehow crushed some of the displayed data, leading to speckles quite similar to yours. The actual data in the file was okay.

Hope its as simple as that.

Cheers

Dennis

[rustigsmed (Russell)]

Originally Posted by bojan

Fingerprint?

hi bojan, it really looks like it doesn't it - i'll take another look but there really shouldnt have been anyone around to put their mitts on the scope!

Originally Posted by Dennis

Hi Russell

I once saw something similar when I was viewing a Flat in The Sky X Pro Camera Control Module and I had the Histogram set to a funky stretch from playing around with a recent image.

When I re-set the default Histogram stretch, the flat appeared normal as per my other Flats.

It seems that my funky manual settings somehow crushed some of the displayed data, leading to speckles quite similar to yours. The actual data in the file was okay.

Hope its as simple as that.

Cheers

Dennis

Thanks Dennis, unfortunately it all seems to be normal. the only thing was I did get some odd things at times - sometimes I switch from NINA to Sharpcap to do a manual refocus (nina doesn't always work for me). i did get banding a couple of times when doing this but reset the camera. but it was across the entire frame not isolated like this one.

[Dennis]

When taking Flats via the Camera Control Module in The Sky X Pro, I inspect the Histogram to check the levels.

The Histogram shows numeric ADU counts for the values of Average, STD, Min, Max, etc. and I always check to make sure that I’m not clipping the whites.

Could it be that the speckles are the results of clipped white pixels being applied?

Cheers

Dennis

[Dave882 (David)]

Russell- could it be ice forming due to a bit of moisture present in the works? If so, drying out the tablets in the oven might fix things.
Also, how hard was your cooler working while taking these shots? I know that I get crazy excess hot-pixels showing up when my cooler is running much over 90-95%. On my old 294mc pro it would show up in a pattern in the centre of the frame very similar to this while on my 2600mc it is more evenly dispersed.

[rustigsmed (Russell)]

Originally Posted by Dennis

When taking Flats via the Camera Control Module in The Sky X Pro, I inspect the Histogram to check the levels.

The Histogram shows numeric ADU counts for the values of Average, STD, Min, Max, etc. and I always check to make sure that I’m not clipping the whites.

Could it be that the speckles are the results of clipped white pixels being applied?

Cheers

Dennis

Originally Posted by Dave882

Russell- could it be ice forming due to a bit of moisture present in the works? If so, drying out the tablets in the oven might fix things.
Also, how hard was your cooler working while taking these shots? I know that I get crazy excess hot-pixels showing up when my cooler is running much over 90-95%. On my old 294mc pro it would show up in a pattern in the centre of the frame very similar to this while on my 2600mc it is more evenly dispersed.

thanks Dennis / Dave - I'm leaning toward ice / moisture. Looking at uncalibrated lights in Blink in PI, the dark pixels don't seem to move. will dry the tablets as suggested. cooler was set to -25. i had the issue on the 2nd night which had a lot more moisture about than the first night. unforunately I took most of my images then!