White images after 3 minute exps?

[stephen99]

I am using the Atik 420 mono with the hyperstar. I cannot get any images over about 3 minutes. The image comes out completely white. Over exposed I guess, but what is the solution for this? I should be able to do much longer exps without a problem. I am brand new to the Atik software and using it. I think it has to just be a setting. Just have no idea where to start?

Thanks

Steve

[MikeM]

I don't know about hyperstar but if you don't get a response here you should check the Fastar yahoo group.

[Chris]

Make sure that Auto Stretch in the Display Dialog is checked, if it isn't then the white level may be set low and so the display saturates very easily.

Also move the mouse over the image and look on the status bar, you should see the X Y position and the pixel value. If it's solidly at 65565 then the CCD is saturated.

It's possible that 3 minutes will saturate the CCD, depending on what your source of light is, so if this doesn't help some more information on how you are doing this would help. including saying what the level is with the shortest exposure (1/1000 sec) and what exposure you need to get a level of about 32,000.

[astrodog73]

I've seen this with my 420m - but so far only when binning 2x2, and exposures of 3 min or more I think.... I have no trouble when using normal 1x1 though, have done 10 min exposures no trouble....