Sony a7s high ISO in crop vs. FF mode

I

icarusfilm

Veteran
I'm about to depart on a production where we intend to use moonlight as available light. Is the a difference that is noticeable in noise when using crop vs FF at high ISO? Will say a 24 1.8 in crop at 50000iso be similar to 35 1.8 in FF?
 
One thing to consider is that a bit more than twice as many photons are hitting the sensor or twice as many photosites collecting those photons are in use in FF mode vs crop mode, so it would not be too unreasonable to expect over a stop more sensitivity in FF mode.
 
It depends if you are taking pictures or making a video. In video (crop) mode I didnt experienced noticeable more noise. In picture (crop) mode you can forget the A7s. Its very noisy
Benn
 
Not just more noise but larger noise and compression artifacts. I'd do some tests and see where the breaking point is going to be for you.
 
Now I pulled the trigger on a Voigtlander 21mm 1.8.
And its all your fault, at least that's what I'm telling my wife.



cyork said:
Not just more noise but larger noise and compression artifacts. I'd do some tests and see where the breaking point is going to be for you.
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nyvz said:
One thing to consider is that a bit more than twice as many photons are hitting the sensor or twice as many photosites collecting those photons are in use in FF mode vs crop mode, so it would not be too unreasonable to expect over a stop more sensitivity in FF mode.
Click to expand...

I keep seeing this claim and it just doesn't make sense to me at all. Intensity of light is based off the amount of photons arriving at the sensor per area. Changing the camera from FF to crop doesn't change the amount off light coming through the lens or the amount of light arriving at the sensor. Sure fewer photons are being read but those fewer photons are in a smaller area so the resulting brightness is the same. Also the sensor doesn't have to perform any differently than it does in FF mode it just doesn't process the data outside of the APS-C size region so dynamic range should not be affected either.

The only different is noise in that the noise is larger because it is a 2.8k image down scaled to HD rather than 4K. The noise appears larger because everything else in the image also appears larger. Other than that the image is identical to FF, and so far my few experiences with performing a digital zoom in camera seem to confirm this as well. I bet if you shoot footage FF and then shoot crop, bring the footage into a compositor and place the crop footage over the FF footage and scale the crop footage down proper size you will see almost no difference between the FF footage and the crop overlayed footage.
 
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