Vivitar 28mm f/2.5 on Sony A7R
How does this old Vivitar do on a modern A7R?
The Vivitar 28mm f/2.5 lens is a serial number 37x which indicates it was made by Tokina. I don’t have a lot of details for this lens, appears to have 6 slightly curved diaphragm blades and a large for focal length 58mm filter thread.
Lens curtesy of Lloyd Shell. Check out his great work at: http://lloydshell.zenfolio.com.
Note: 4k video is 2160 LW/PH
Note: HD video is 1080 LW/PH
Comments on the Results
Central sharpness and resolution are very good at f/2.5 and excellent by f/4. Even from wide open the lens is good in the central region. However, corners are not a strong point of this lens.
There is some field curvature, but nothing dramatic.
Distortion is average with 1.2% barrel.
Lateral CA is noticeable in the corners.
Flare resistance: Haven’t checked.
Measured Focal length is 30mm at 1:35 magnification
Pros and Cons
- Center Performance at most settings
- Corner performance at any setting
The colors are selected based on overall MP, don’t compare the colors between systems. So relative to max sensor resolution this doesn’t do as well as the lens does on the A7 relative to its (lower) sensor resolution, but it still resolves more detail on the A7R then it does on the A7.
This lens is nice and strong in the center, although at infinity focus it looks hazy all over the frame from f/2.5. Center is very high resolution from f/4, pretty much maxes out the A7R. This lens might make a nice central subject lens on APS-C or full frame, but I might look elsewhere if you need corner performance.
Consider donating, it is about $50 a lens to rent.
I know some people like comparison crops, but remember, real images have things like field curvature and focus variations so it is sometimes hard to make these match perfectly. The full image is underneath and the crop areas are from top to bottom: center, 24×36 corner, and APS-C corner (24×36 Partway).
Don’t trust this first shot too much
Above: f/2.5 (I think focus is in corner on this shot for whatever reason)
Above: f/4 (I notice corner is sharper than f/8 shot, so again, think focus could be in corner)