Quote:
Originally Posted by gregbradley
Good work on your experiments there. I find the problem in luminance rather than the blue channel (it tends to be in all channels).
So the theory its the colour correction of the scope is likely to be incorrect otherwise it would not bloat in luminance like it does.
I'd say the problem is more too small wells. The other possibility is IR bloat which may affect all of the filters?
Greg.
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Hi Greg, I would say that Peter's results and yours show quite clearly that the problem is a violet halo. Peter showed that a filter that removes the bottom 40 nm or so essentially cures the problem. The only 2 channels that can actually see the violet light are blue and luminance - which explains your lum result. This is not a criticism of the scopes - I am sure that they work exceptionally well - they just don't correct well enough in the violet (which is outside of the design range) to be suitable for use with a camera with small pixels and very high violet sensitivity.
Just to be clear, exactly what do guys mean by the term "bloated". If that just means bigger stars, then that is certain to happen - the Trius will produce equivalent stars that are 4x the area of those from the 16803 (or 1.4x the area of those from the 8300), simply because it puts 4x as many pixels under each star. Everything else in the Trius image will also be 4x the area including galaxies etc. So if you want to compare Trius images with 16803 images, you need to downscale the Trius images by 1/2 first. If you mean that the cores are saturated, that is due to to the combination of very high sensitivity and smaller wells of the Trius - saturation can easily be overcome by using short subs (eg a couple of minutes) and the Trius will allow you do that because of the low read noise. But fixing the saturation will not make the stars any smaller - it will just stop the cores of bright stars from losing detail and going white