First light Atik 314L+ Lots of hot pixels?

[Tommy B]

I had a chance last night to try out my Atik 314L+ colour camera for the first time. I wasnt expecting much as I knew I'd spend most of the time getting to grips with the camera and software but I did end up with an image.

Its out of focus and noisy due to bad seeing and me not cooling the camera enough but what concerns me are the high number of hot pixels present (see attached photo). The images are converted from fits files to Tiff's using Artemis RGB but the hot pixels are present right from the preview image in Artemis Capture to the stacked end result. Is it common to see this many on these cameras? my dslr has nowhere near this many and thats a bigger chip.

Thanks.

Tommy B.

[dmahon]

Most software has a routine to remove hot pixels and if you dither between frames stacking will get rid of them too.

[swag72]

What temperature were you cooling to? I ask as there was a noticeable difference in hot pixels for me once I got down to -5 and more.

[Tommy B]

I was'nt running very low at all. I think I had the cooler running at 1 degree C and ambient wast about 6c to 7c. Strangely on one frame the hot pixels cycled their colours. They all seem to be Red, Green and blue like the bayer matrix so im wondering if its maybe a problem with colour alignment and these pixels are actually stars?

Pretty much a 90% chance of a clear sky tonight so I'll get that cooler down to a better level and experiment some more.

Thanks;)

[Tommy B]

Just done some reading up and it appears they may be stuck sub pixels! Which are broken and will permanently show red green or blue. I have gone through the images and they occupy the same pixels even when there is movement in the frame. Anyone else ever get this?

[ncjunk]

Yes, i have an old art285 which has a few hot pixels so i have to subtract Darks and slightly move the mount every now and then between subs so the hot pixels dont appear in the same place on every sub.

[Tommy B]

Yes, i have an old art285 which has a few hot pixels so i have to subtract Darks and slightly move the mount every now and then between subs so the hot pixels dont appear in the same place on every sub.

Thanks for the tip. Yesterday night I followed your advice about moving the mount once in a while and that seemed to remove the stuck pixels for the most part;)

However, I decided to take a dark frame with the camera to see the extent of bad pixels and Im quite shocked. I knew ccd chips were always going to have the odd bad pixel but my dark looks a bit excessive! "See attached image"

What do people think?

[AstroLuke]

Thats quite a few hot pixels there! o: Maybe you should dcheck if its the camera in general or if its only the one you have! If its only yours maybe you can get it replaced?

[RobH]

That's more than you would normally expect on a 285 chip, but not excessive.....you should see a dark from a kodak 8300 chip....they look like it's snowing!

Darks should remove them easily enough.

Rob

[martin_h]

That's more than you would normally expect on a 285 chip, but not excessive.....you should see a dark from a kodak 8300 chip....they look like it's snowing!

Darks should remove them easily enough.

Rob

Your'e telling me!! badly tuned TV set springs to mind..