Best DSLR or ILC for Night Sky Imaging?

Started Nov 8, 2017 | Questions thread
rnclark Senior Member • Posts: 3,755
Re: Best DSLR or ILC for Night Sky Imaging?

swimswithtrout wrote:

rnclark wrote:

As we've seen in past discussions, the lens is far more important, given a relatively modern sensor. Nightscapes do not push a sensor unless you cripple it with a tiny aperture. Except for some models that eat stars, any recent camera, paired with a good lens, like 35 mm f/1.4 or24 f/1.4 will do a great job



Though if you can shoot at ISO 12,800-100,000 for 29 sec., with very low noise before the star eater even shows up at 30 sec, using one of your preferred f1.4 lens',there is a very strong point to push the Sony A7s !

Nikon/Pentax buy their chips from Sony and have the same "modern" performance, it's Canon that keeps falling further and further behind.

If you are looking for a "one shot" camera for nightscapes, fixed tripod, than it's impossible to find a better camera than the Sony A7s . It's a "one of a kind" camera optimized for low light photography, and shooting on fixed tripod and it's short exposure limitations will make the "star eater" a moot point.

sharkmelley wrote:

If you don't mind the large pixels then the Sony A7S is the best out there in terms of sensitivity in low light

There is another factor being overlooked here. In nightscape photography, we are using relatively fast lenses, and really fast if using f/1.4 lenses. That means collecting a lot of light from the sky very quickly. And modern lenses are quite sharp wide open. If the lens limited resolution one would not see much difference in star star size as sensor pixel pitch decreases. So the signal we get from stars and other small detail in the night sky is a combination of signal from the star, nebula, galaxy, etc plus the signal from the sky.

Large pixels collect more light from the sky reducing contrast with faint stars and other small detail. Thus large pixels in this situation produce lower contrast which becomes a significant loss (of contrast) on small faint objects. Thus noise from the sky will swamp faint signals on small objects, like stars, and other small details.

This effect is shown in Figure 9 here: where pixel sizes of 6.54 microns is on the left, and 4.09 micron pixels is on the right.  (The Sony A7S has 8.4 micron pixels.)

Again, with fast lenses, noise from the sky is far greater than read noise and dark current (unless imaging in a really hot environment, like Phoenix in August).

And you can synthesize any size pixel you want by binning. For example, bin 7D2 4.09 micron pixels 2x2 and get 8.18 micron pixels, or 3x3 and get 12.3 micron pixels.  Watch your image quality degrade.

Optimum pixel size for the sharpness of current fast lenses is 4 to 5 microns.


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