Quote:
Originally Posted by Atmos
Although no exact it would be kinda a like:
1) ZWO 150mm f/4 with ASI1600 (16mp MFT)
2) SW 300 F/4 with Canon 1D MkII (16mp FX?)
In short, both are imaging at the same image scale but the 12" sucks in 4x the amount of photons. #2 may have more read noise but that just means longer subs to over come that so #2 will give a more more detailed image with greater contrast. 4x the number of photons for the same resolution.
Because twice the read noise requires 4x the exposure and twice the aperture equals 4x the photons per second, they may very well cancel each other out. Subs should end up the same time but the #2 will have much greater contrast.
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Well, possibly, however the cameras, in this example, are not equivalent, the Canon, in its natural state, is uncooled and the thermal noise will be significant compared to even an uncooled ASI1600 (which uses the whole body as a heatsink) and has minimal internal processing which generates heat). Shooting longer subs on the Canon will substantially increase the thermal noise effect and as sub numbers increase the sub quality will decrease - without substantial cool down delays between subs ( which are not very effective in dslrs anyway).
For comparative purposes, the cameras would need to have equivalent thermal noise impacts throughtout the duration of the test.
