AFS-S issue - Returning my XT5

robert1955 wrote:

Erik Baumgartner wrote:

robert1955 wrote:

Erik Baumgartner wrote:

robert1955 wrote:

DanFry wrote:

Yannis1976 wrote:

DanFry wrote:

BeatX wrote:

What? Did I just read again, that another X-T5 user reports false focus box confirmation in this new improved Fuji auto focus system? What is going on here?

If you refer to my post, then no, since I am not (yet at least) an X-T5 user. I was talking about diffraction, with APS-C 40 MP @ f/8, forgot to say that key word. Diffraction negatively affects the level of detail in an image, be it otherwise in focus. That's my understanding at least and one of the factors that make me hesitate to upgrade to the X-T5 for my mostly landscape photography.

Dan

I think that diffraction starting point is related to sensor size and not its resolution, but could be wrong. Personally I haven't experienced with the XT5 any worse IQ due to f8 yet...

No, that is not my understanding. Diffraction is a function of pixel size only, the smaller they are, the more diffraction as you close down aperture. That is my firm understanding, but happy to be corrected with a scientific exposé

Dan

Implication of that would be that there is no diffraction if the sensor is film, which is not the case

The effect is much the same. Film has grain size, digital has pixel density.

Are you saying grain causes diffraction?

No, I’m saying grain size determines the resolution potential of the film, as does pixel density in a digital sensor.

Well, we were talking about the possible influence of pixel size on diffraction. Dan was saying that it is only pixel size which cause diffraction. I say he's got that wrong, it is the size of the sensor [including film] that is the main cause

Neither is the cause of diffraction, light passing through the aperture blades is the cause of diffraction. As the aperture is stopped down, diffraction causes the size of the smallest possible focused beam of light to increase in size (known as an Airy disk), The pixel density or grain size will determine whether or not that now larger beam is fine enough for detail to be fully resolved at the single pixel level. With very densely packed pixels, at some point a decreasing aperture size will produce an Airy disk that is now too large to cover individual pixels exclusively. As the beam is now only able to cover multiple pixels, the resolution becomes limited. As APS-C sensor pixels are typically more densely packed, diffraction typically becomes an issue at wider apertures than FF, but a super high resolution FF sensor like the Sony A7RV (61MP) will suffer the same diffraction limitations as a 26MP APS-C sensor because the pixel density is about the same.