LensRentals has loaned me a Hasselblad XCD 55mm f/2.5 V lens for testing. There have been reports of extreme amounts of focus shift in V-series lenses. Focus shift is usually caused by undercorrected or overcorrected spherical aberration. I haven’t seen that myself, so I took a look today. I have a test I used to perform for this, but I don’t have the space to do that test anymore, so I focused wide open on a Siemens star at about 7 meters, and stopped down, making captures without refocusing. Developed in LIghtroom with defaults except for white balance to the background and sharpening turned off.
The image is a little sharper at f/4.
We are losing a tiny amount of sharpness at f/5.6 due to diffraction.
At f/8, diffraction takes a greater toll.
At f/11, visible aliasing is gone.
Pretty fuzzy at f/16.
If you compare the above images to the images in this post, where focus was optimized for each aperture, you’ll see that there is no apparent focus shift.
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