Olympus OM 24mm f/2.8 on Sony A7R

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.

SAM_0615 SAM_0616

Optical Performance

OM24f28_A7r_files001
OM24f28_A7r_files002
DSC00174__1-4 sec_YBR52_18_multi_cpp
OM24f28_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 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).
DSC00174
Shot at f/8 (f/11 marked). Click on image to see larger size and cyan corners.

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.s

Aperture Weighted Center Partway Corner
f/2.8
18.5 MP
28.1 MP
10.5 MP
4.3 MP
f/8 (f/11 marked)
23.4 MP
30.6 MP
18.3 MP
9.8 MP

Bottom Line

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.





9 Comments

  1. Putut says:

    Looks like you have a bad copy. I have compared quite a few MF lenses using the A7, and the OM 24 2.8 is a VERY nice wide angle lens.

  2. admin says:

    Have you checked yours to see if you see cyan tinted corners? It is fairly minor, but obvious on the white test chart.

  3. Putut says:

    There is quite some vignetting at large apertures, but very minor color shift. Nothing compared to the NEX 7 with the SEL 10-18 (I have done a direct comparison).

  4. Muik says:

    Hi. I have been looking and looking in my pictures and I have not been able to see those cyan tinted corners in then. I will try on some other surface and come back, but your conclusions just came like a big surprise to me.

  5. admin says:

    It is quite noticeable on snow. Which I have seen far too much of this winter 🙂 See my test shot though, the white balance in the central region is different then in the corner region. In real world shots it probably won’t really be noticeable in most situations (until you have some object with the same white balance across the frame). The ZEISS 24-70mm is actually just as bad or worse, but corrections should take care of it.

    Just to add, vignetting exaggerates this, if you correct vignetting it will probably be difficult to spot. From my perspective (reviewing lenses), the Pentax and Olympus both have some greenish cast to the corners and the Canon FDn f/2.8 does not have near as much so my inclination is to recommend the Canon. This is not saying the others are “bad”.

  6. Organo Pleno says:

    Olympus changed the lens diameter a bit of the two lens elements just behind the aperture for the latest series of the OM 24/2.8. These elements are a bit smaller compared to the earlier versions. This made construction more easy (no screw in rings to hold them), but performance worse. I have had all versions of this lens (even the last AF version). The earlier Zuiko MC is the best version. The older H. Zuiko lenses are also very good, but the lens coatings are a bit less good compared to the MC and later versions. The latest Zuiko version (and also the 24/2.8 AF) is the worst version due to very poor corner performance. That is a pity, because corner performance is excellent with all earlier versions.

  7. Helmut R says:

    Since a couple of month I have a Zuiko MC Auto-W 2,8/24 mm for my Sony A7R as wide angle lense (besides of Sony/Zeiss 2,8/35 mm and 1,8/55 mm). It really is a great lense!! (What I still am missing for this camera is an autofocus macro/portrait lense say 2,8/80-90mm)

  8. Bill Stanton says:

    Hey Organo (or anyone else), at what serial # does the OM Zuiko 24/2.8 go from the smaller elements to the newer, less sharp corners version?

    Or should we just stick to the pre-200xxx lenses and leave it at that?

  9. tiltedplane says:

    I use this lens on my A7r and have to say that it’s really terrific. I’ve tested sharpness against the Sony 28mm f/2.0 and the Nikon 14-24mm and they are all remarkably similar. I’d say the Sony comes out ahead in sharpness at f/2.8, but barely, and from there on it’s a tie, to the eye. Other lenses (like the kit zoom) are terrible by comparison.
    Just for some field feedback.
    Oh, and I have the latest MC version of the 28mm f/2.8, which I’ve heard is visibly better. Though there is still a lot of CA to deal with.