(02-08-2023, 10:20 PM)Klaus Wrote:(02-08-2023, 07:08 PM)Rover Wrote: Pretty steep pricing, although the feature set is nice. I guess people are going to stop it way way down to shoot small things anyway, so the max. aperture doesn't matter much for that kind of use.
This is a bit problematic - the effective aperture gets smaller at closer focus distances. If you stop down further you will be in diffraction territory already.
Some fellow suggested that it's f/7 at 1:1.
Yeah, well, that is correct. However, it is not so much the aperture that makes this happen, but the enlargement or magnification factor. It happens with ALL macro lenses at 1:1. You lose 2 -stops in comparison to infinity because the projection area on the image capture device, the sensor, is 4X the size of that at infinity. The image sensor sees only 1/4 of the total image projected, which means it only gets 1/4 of the light. IOW, it loses 2 f-stops, just because of the magnification factor. And in this case, that means that the effective lens opening becomes F/7, starting at F/3.5.
Having said that, the real lens opening is still F/3.5 if you shoot wide open at 1:1, from a DoF PoV, that doesn't change. It just only captures 1/4 of the total image projected by the lens.
In addition, diffraction is a relative thing with large magnifications. There is generally no other way to capture such images. The thing to do really is to stack images, and/or use a very short FL for large magnifications, something I did a lot in the past (Fhotar 12.5). Even then the results are never optimal for 3D objects.
Kind regards, Wim
Gear: Canon EOS R with 3 primes and 2 zooms, 4 EF-R adapters, Canon EOS 5 (analog), 9 Canon EF primes, a lone Canon EF zoom, 2 extenders, 2 converters, tubes; Olympus OM-D 1 Mk II & Pen F with 12 primes, 6 zooms, and 3 Metabones EF-MFT adapters ....