Quote:
Originally Posted by Shiraz
I think that GSO/ASA combo is the basis of the Boren-Simon scopes. Lots of images from them out there and they look OK to me.
the ASA corrector specs show it covering the full 8300 sensor.
Worth checking how much sensitivity you lose due to waveband shift in narrowband filters at the light cone edges at f2.8. Might limit how narrow the filters can be or reduce the extra gain you get from the faster scope.
Crikey you are brave to want to go to f2.8 though - wasn't getting/keeping things aligned and focused at f4 enough of a challenge? I would be particularly concerned about image plane tilt with that fast a scope. Carbon fibre will help with temperature stability, but there will be other bits in the image train that are aluminium, so you will still have focus drift with temperature (enough to be an issue at f2.8). Good luck though - sounds like a fun project.
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I did think about the bandpass shift at f3 but using 7nm filters I'm not sure if it will be an issue. If it was I could potentially screw the filter to the front of the corrector and filter it at f4? Not sure if anyone has tried that but it seems to logically be possible.