Quote:
Originally Posted by Shiraz
Clive, thanks very much for the info - never seen specs for lateral charge diffusion (assume that is what it is) published for any astro sensors, except maybe Kodak's claim to produce "low smear" chips.
This could possibly explain why planetary imagers find that going well beyond Nyquist sampling requirements yields additional detail - maybe we are using oversampling to deal with sensor diffusion blur. Heavy handed oversampling may also be worth pursuing for DSO resolution improvement as well. Regards ray
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Hi Ray...
There may be two factors at play here... electrical charge diffusion and/or light spill through the side walls of the pixels. Without some manufacturer specific 'secret sauce' the signal spill may be inherent to all CCD's made from any given substrate... I don't pretend to know the answer to that.
Incidentally, if anyone wants to simulate the effect of adding the equivalent of 1/4 wl of spherical aberration, just add a 35% central obstruction to your OTA.
Interesting that RC's have a 35% central obstruction basically by definition, and they seem to work fine more often than not. The fact that they routinely deliver higher resolution images than Newtonians of similar aperture might be just a function of the over sampling achieved by the longer focal length.
Also, (i'll re-iterate the point) the fact that optical tube assemblies with 50% central obstructions are practicable as prime focus telescopes should serve as a data point for how much spherical aberration can be tolerated in this application... at a guess, this is equivalent to 1/2 wave, give or take.
~c