Couple of questions - Sony a6000

Started 7 months ago | Discussions thread
mrbenji
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Re: Couple of questions - Sony a6000
In reply to Slynky, 7 months ago

So, the a6000 tries to recover some of the resolution lost to lenses that aren't up to that 24MP quality...I'll have to read it later. Thanks !

He's referring to Sony's "Diffraction Reduction" technology -- that doesn't actually have to do with compensating for glass that a sensor out-resolves. Instead, it's intended to compensate for the effects of diffraction... diffraction is a physical effect that causes reduced fine detail at high (small) apertures, regardless of how good the lens is.

A drawback to higher-megapixel sensors is that diffraction begins at larger apertures vs. lower-megapixel sensors of the same physical size (APS-C, FF, etc.). As I understand it, however, "diffraction limits" aren't hard limits beyond which image quality drops of a cliff, but rather are the beginning of a downward curve, i.e. they are the aperture number beyond which effective resolution begins to gradually erode.

I can't seem to find the most helpful (to me) diffraction calculator I've seen in my wanderings, but iirc a 16MP APS-C sensor starts showing diffraction effects at around f11 -- but as it's a gradual decline, that doesn't mean that the effects of greater DOF on sharpness will be overwhelmed by diffraction at, say, f16. In other words, there are situations where your composition and overall sharpness (due to DOF) will be clearly better-off at f16 or even f22, despite diffraction.

I assume the comparable diffraction limit for 24MP APS-C would be nearer to f8, but you've got higher resolution to begin with, so with a good lens I'd hope the effective resolution @f16 would remain superior to a 16MP APS-C @f16. With my layman's understanding of physics I certainly can't think of any way the effective resolution could be *worse* on a 24MP vs. a 16MP sensor of the same size, all other factors being equal.

I'd be interested, however, to hear from others who understand this better than I do.

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Sony a6000 Sony Alpha NEX-5 Sony E 18-55mm F3.5-5.6 OSS Sony E 50mm F1.8 OSS +5 more
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