Unable to calibrate out column defect

[JimMcKay]

Hi all,

I've had my 383L+ for well over a year. About a month ago the camera developed a column-like defect which I have been told is typical of the 8300 chips.  It starts on one side of the frame and extends about half-way across the frame. I shot a new series of calibration frames and tried to calibrate my most recent set of images. The result is now I have a dark line extending into the frame. When I examined the calibration frames, the dark shows no line, the flat shows no line, but the bias frames show one or two of these lines. I suspect that something must be up in the short exposure of the bias frames.

Anyone else with a 383L+ camera seen this type of defect and how did you manage to address it?

Thanks,

-jim

[joelshort]

I have seen this too, but unfortunately I don't have a good solution to give you.  Have you tried calibrating without using the bias frames?  My understanding is that bias frames aren't necessary if using darks and flats.   I'm just curious if you see different results without using Bias.

[Kh3ldar]

I have this issue with my new 460ex - my solution is to apply a bad pixel map to the master bias frame in Maxim then you don't get the black line (I reuse the same master bias every time.)

Alternatively dither when imaging and the line should theoretically average out

Hope this helps,
Stephen