Minolta A1 vs. iPhone 13 Pro, or the king is naked

toughluck wrote:

Rishi Sanyal wrote:

Thank you for that DOF calculator, as the one I was using clearly gave me some incorrect numbers. This is the one I used:

https://www.dofmaster.com/dofjs.html

... where if you enter a 2/3" sensor with 50mm focal length, F4.5, 0.5m subject distance, it indicates a DoF of 0.02m or 2cm, which is nearly an order of magnitude off! (It should be 3mm, so given my 0.5m assumption, had I used a correct calculator, I would've said 4-5x less DoF). Also, last night I was digging in the EXIF of your file for a subject distance but couldn't find it, which is why I made that assumption, but now I see the 0.25m distance in parentheses in the depth-of-field field.

So I agree with your calculations, though if we're really being technical here, I'd say that since you're drawing your conclusions from comparing the images at 100% magnification, you should actually use a CoC of 1µm for the iPhone.

But even then, as you say, the the DoFs are comparable, and the differences probably have to do with a number of things: quality of optics, optical performance at minimum focus distance, higher SNR on a 2/3" sensor, less noise reduction on the Minolta... but one can only guess without setting up a controlled experiment.

-Rishi

I'm actually going to try my hand at a controlled experiment. I have several different cameras that I want to check to find out whether detail in the iris is actually possible with small sensor cameras at all, or if diffraction will destroy all detail before it ever reaches the sensor.

If detail is lost in noise reduction, then computational features should show details at least sometimes. If it's lost because the sensor is too small and the lens is already beyond its diffraction limit, no amount of computational trickery will ever improve the result.

Post back with your results. I will say though that between your A1 and the iPhone, the diffraction should be similar, since F4.5 on a 2/3" sensor is ~F18 equivalent, while the iPhone's ultra-wide is roughly F15 - F16 equivalent, so the two cameras should show roughly similar levels of diffraction.

(Diffraction is related to equivalent aperture, or physical size of the exit pupil, not the absolute f-number).