Quote:
Originally Posted by pmrid
These cameras have a mechanical shutter and it occurs to me that in short exposures, such as you do for flats and the like, there may be an artifact created by the opening (and closing I guess) of the shutter.
Anyone else experienced this?
Peter
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Yes!
I owned a U47 for time. Apogee use Melles-Griot shutters with an iris closure.
They cause non-linear flat field exposures that has a measurable effect up to about 10 seconds.
I found this made taking sky-flats (read most accurate) nearly impossible.
The only fix was to take dome flats, and adjust the field illumination source to allow 15-20 second exposures with 30% full well capacity.
P.S.
I ended up returning the camera due a plethora of (other) problems.