Posts Made By: Tom Lindquist

What you are calling "swooches" are actually "Ears", I believe.

Ears are taken to result from slow rebound of a digital to analog converter (DAC) when driven to saturation. They are common on the SAC-8 camera (long exposure modified webcam), but they are very short (leading to the VanGogh analogy as there is only one "ear" present for a bright star) while yours are much longer. There's a comment already posted along this line.

Several possible approaches:

You can ignore them and put a false floor in the image just above the true background level.

You can shoot shorter subs rather than longer, until the bright star no longer saturates. (so try a second or less exposures?)

Clone tool, etc, to patch background eliminates ears themselves crudely.

An aperture mask with a 60mm or whatever diameter hole placed over the open end of your telescope could be ideal for getting control of these over-bright stars that are saturating when exposure is set for faint nebulosity. That seems worth trying.

Hope this helps.

Tom Lindquist

Charles Hakes said:

I was hoping someone could tell me about the swooshes. These were short (3sec) exposures as I was playing around with image scaling. Obviously very stretched here. Camera temperature was -40C. (almost as cold as my feet felt). Looks like it must be something to do with read noise, (?) but I don't recall this discussed. Thoughts?

Thanks,
Charlie

Charles Hakes said:

I was hoping someone could tell me about the swooshes. These were short (3sec) exposures as I was playing around with image scaling. Obviously very stretched here. Camera temperature was -40C. (almost as cold as my feet felt). Looks like it must be something to do with read noise, (?) but I don't recall this discussed. Thoughts?

Thanks,
Charlie

Charles Hakes said:

I was hoping someone could tell me about the swooshes. These were short (3sec) exposures as I was playing around with image scaling. Obviously very stretched here. Camera temperature was -40C. (almost as cold as my feet felt). Looks like it must be something to do with read noise, (?) but I don't recall this discussed. Thoughts?

Thanks,
Charlie