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Length of bias frame

Starpartyguy
in PixInsight
I remember some weeks back a mention of bias frames for cmos cameras, where Adam suggested they should be 30 seconds long. I’m currently at Cherry Springs hoping to image tonight. I have a QHY 268 m, binned 2x2. I took 30 3 minute darks. And hope to shoot M101 if it stays above the trees long enough. Is 30 seconds appropriate for flat darks?

Comments

  • BlockHeadBlockHead
    Whoah... hang on there partner!
    We have to be very careful about language here!

    Bias frames are zero second (or insignificant) exposures. What I think you are confused about is that I say that for normal CMOS and CCD cameras you can use a bias to likely calibrate flats (or lights) for exposure times up to 30 seconds (if you do not have significant dark current). This means you can take flats at any exposure time you would like and calibrate them with a single master bias. This I said.

    You can also create matching darks to calibrate the flats. This will also always work.
    The point is...for many cameras you do not have to spend extra time creating darks of different lengths. This is true for cameras that do not have amp glow or other electronic signatures. If you do have amp glow and things... yes, you should make matching darks to calibrate flats.

    So in your question... you did not say how long your FLATs are. They are probably short..and require either just a bias or matched darks a I describe above.

    -the Blockhead
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