Vivitar 28mm f/2.5 on Sony A7R

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.

SAM_1012 SAM_1013

Optical Performance

VivTok28f25_A7r_files001
VivTok28f25_A7r_files002
DSC00366__0.5 sec_YBR51_18_multi_cpp
VivTok28f25_A7r_files003
Please click on the tab you want to view. Only 1 tab may be active at a time. MTF, Distortion, and Lat CA data acquired using Imatest
MTF20 Chart maxes at vertical resolution of the sensor which is 4912 LW/PH for A7R. Anything above that is meaningless. The MTF50 chart is set at the value where the best lenses perform in the center, or about 3850 LW/PH on the A7.
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

Effective Resolution

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.

Aperture Weighted Center Partway Corner
f/2.8
13.6MP
23.8 MP
3.9 MP
1.7 MP
f/8
20.2 MP
29.9 MP
11 MP
8.7 MP

Bottom Line

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.





Crops

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
TokViv_wideOpen
Above: f/2.5 (I think focus is in corner on this shot for whatever reason)
TokViv_f4
Above: f/4 (I notice corner is sharper than f/8 shot, so again, think focus could be in corner)
TokViv_f8
Above: f/8

8 Comments

  1. areichow says:

    I have a copy of another Vivitar 28mm f/2.5 – serial 22xxxxxx, 67mm filter thread, FD BL mount. I think this is the Kiron version. I wonder how it would compare to your VIvitar 28mm f/2.8?

    It’s not the greatest lens – big, heavy, weak wide open, and very susceptible to flare. The contrast wide open is poor enough that it’s very hard to use with focus peaking with my usual JPEG settings. It’s one of the first MF lenses I got for my NEX-5R.

  2. admin says:

    I will test one, I think I have a couple copies of that lens. I really like it for infrared, never really tried it for color. Probably right though, most of these older inexpensive lenses weren’t great wide open.

    Eric

  3. areichow says:

    Cool, thanks!

  4. Tg-Ranger says:

    Thanks for the review, i picked one up a while back but never got to use it i now have a Sony a7S would you know which adapter i need for that?

  5. admin says:

    Depends on what mount the Vivitar is for, any markings on it?

  6. Tg-Ranger says:

    I could take a photo of it? It serial is 2222XXXX if that helps!

  7. Mike says:

    I had one of these 28mm 2.5 lenses in 1974. Remember they were made for film cameras some 40 years ago. It was my primary lens on a Yashica TL Electro X body. I made hundreds if not thousands of beautiful imagery until they came out with a 17mm 35 wide angle lens. Then I switched to that one and never looked back.

  8. Johan says:

    I have the same lens. It was decent on my Pentax film camera, but as you note, it is not a very strong performer on a modern digital camera. There are much better 28mm lenses out there (like the Pentax Takumar 28mm).