Is FF sensors going to slowly phase out?

Started Apr 11, 2013 | Discussions thread
forpetessake
Senior MemberPosts: 3,893
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Re: it depends on your definition of 'slow'
In reply to tomtom50, Apr 15, 2013

tomtom50 wrote:

EinsteinsGhost wrote:

forpetessake wrote:The f-stop determines the brightness, but you need to integrate over the area to get the total light, collected by the lens, and that's exactly what determines the photon noise part of S/N ratio.

Nope. Larger sensor uses more light (for a wider FOV), but the light falling on the sensor over the same surface area as a smaller sensor doesn't change.

I think you are talking past each other. forpetessake is speaking of brightness in the sensor of lux, lumens/area. It is correct that lenses of equal aperture deliver the same lux, and since lux is lumens per unit area more area means more lumens.

This is a main reason a larger sensor tends to outperform a smaller (I wrote tends, many exceptions exist) sensor. Photon shot noise is related to the number of photons falling on the entire sensor for a given output scale.

Correct. It's also frequently the sensor QE creeps into equivalence discussions. Despite of the fact, that it's always a camera/lens system one has to deal with, it still makes sense to clearly separate the lens and sensor contributions. It's the lens' task to collect photons, it's the sensor's task to convert them into electrons. The first scales with crop factor, the second depends on technology, design, etc. Otherwise, all sorts of convoluted discussions taking place, like 25/1.4 on Olympus OM-D is equivalent to 50/2.8 on old Canon 5D only for DOF, but the old FF sensor has low efficiency so it's equivalent to 50/2 for light gathering and it's equivalent to 25/1.8 on older m4/3 Olympus for light but equivalent to 25/1.4 for DOF, and so on.

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