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Just a small point on "megapixels"
If you count an Astro-mono camera in the same way as a "terrestrial" camera you need to look at a terrestrial bayer matrix (RGGB) and realise the likes of Canon Nikon Pentax et. al. interpolate data and place it in non-sensing pixel locations.
With "normal" daylight scenes this causes no problems, but with point or spectrally narrow sources (eg Astronomy) you will lose information.
eg. a 24Mp Canon camera only has 6M red pixels.
Using the same concept then, a 16MP mono camera doing a LRGB shot actually has 64Mp of data, but you can't get it with "one shot"...you need four....
This data not only 16 bit, but spatially more highly resolved (ie you are not interpolating colour data) than a "24Mp" one shot camera.
Plus with a luminance (ie unfiltered) domain, with all other aspects being equal, your S/N will be better as well.
P.S.
Mono cameras also perform significantly better in narrow band. eg. H-alpha , SII, OIII as they fully capturing the selected bands,
as opposed to single shot colour sensor than will render a red, pre-filtered version of say H-alpha, with 18 million green and blue pixels doing..well..not much
Last edited by Peter Ward; 15-12-2011 at 09:59 PM.
Reason: clarification
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