Olympus OM 24mm f/2.8 on Sony A7R
How does this classic, and very compact prime hold up on the Sony A7?
This is a copy paste of the A7 review, but I added charts for A7R and updated comments as appropriate. One of the things I love about these old OM lenses is how compact they are. This is notably shorter than the other wide lenses from the time, and it had a fairly short flange distance.
The lens is fairly compact and dense, weighing in at 185 g. It has 6 slightly curved aperture blades, and a standard for the class minimum focus distance of 0.25m. It has a 8 elements in 7 groups, which is fewer than others in its class. It has standard 49mm filter threads. Aperture adjustment is only in full stop increments and is marked to f/16.
Note: 4k video is 2160 LW/PH
Note: HD video is 1080 LW/PH
Comments on the Results
Central sharpness and resolution are excellent. Even from wide open the lens is sharp in the central region. However, corners trail notably. It is important to note that based on shutter speeds between the different f/stops, the markings are not accurate. For example, going between f/2.8 and f/4, only dropped the shutter speed from 1/25 to 1/20 (due to vignetting wide open I usually see between 1/2 to 2/3 stop change in shutter speed, but this was only about 1/3) By the time you reach f/16 it is more like f/11. So at least my copy of the lens only goes between f/2.8 and f/11. This is important to consider with the resolution chart above. Compare f/16 on the OM to f/11 on the Canon.
There is heavy field curvature, so that the corner performance is only reached focusing in the corners. You can still get good cross field performance at f/11 (marked) or higher and if you don’t focus in the center. The little hickup at f/4 is just from slight focus variations due to the heavy field curvature.
Distortion is similar to most of this class lens and is complex with primarily 1.8% barrel. Maybe a bit more barrel distortion but a bit less wave.
Lateral CA is noticeable in the corners wide open, but is not severe.
Flare resistance: Haven’t checked.
Measured Focal length is 26mm at 1:35 magnification
This lens has a color shift you will want to correct using Adobe Flat Field or Corner Fix (or equivalent). It has moderate cyan tinted corners on both the A7 and A7R. This persists through a good portion of the frame (probably what I would consider partway and corners).
Shot at f/8 (f/11 marked). Click on image to see larger size and cyan corners.
Pros and Cons
- Center Performance at all settings
- Small Size for Class
- Corner performance until f/8 (f/11 marked)
- Color shift (cyan)
- Full stop aperture clicks
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.s
|f/8 (f/11 marked)||
Compared with the A7, the A7R does much better in the center, a tad better partway out, and about the same in the corners with this lens.
I would avoid this lens for across the frame sharpness, at least based on my sample. A better sample could have better corners, and I will keep my eye out for ones to test. I can’t imagine a better sample avoiding the color shift issue, and since the Canon has virtually none, it makes this lens a hard sell. It still is very compact and build quality is nice. A friend is loaning me a Pentax 24mm f/2.8 I will test as well.
The lens is very strong if you are only concerned with center sharpness.
Consider donating, it is about $50 a lens to rent.