Quote:
Originally Posted by pmrid
Speaking entirely from a lay perspective, I would say that adding a filter-layer such as that window film would have a negative effect on your flats which would no longer be ambient light as seen through a LRGB etc filter but as seen through that filter and that film so your flat represents only that bandwidth which they both allow to pass. Can that be good?
Peter
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The short answer is I don't think it matters, but I'm very open to being corrected on this.
My "lightbox' is made from an electroluminescent panel in a cardboard box. It's kind of blueish anyway and when I do my narrowband flats my Ha and SII exposures are about 5 times longer than my OIII images to get a fairly consistent white level.
Certainly when taking flats through LRGB filters the exposures will be very different lengths to get images with a count around 25k but I'm not using the flats to calibrate colour but just to eliminate gradients and dust etc.
However after seeing Ricks post I think I'll just chuck some sheets of paper over the panel and see how how much light they absorb.