Over the last few months I have amassed a bunch of old Olympus OM lenses. They are tiny, generally cheap, all of them are optically good, and they fit and work well on my Canon 5D MkII. Here they are:
They're sitting on an antique 12" vinyl record,which helps to give an indication of scale. Moving widdershins you can see an Olympus 21mm f/3.5, a 28mm f/3.5, a 50mm f/1.4 and a 50mm f/1.8. Mounted on the OM-10 is a 24mm f/2.8, plus the Winder 1 accessory and the manual shutter speed adapter. The 28mm f/3.5 is fitted with a generic OM/EOS adapter. My lens has a date code of E06, which means that it rolled off the production line in June 1980. Despite being thirty years old it is still in perfect working order, with no rattles or creaks. Countervailing is a great word, very manly and hard-sounding.
Almost as good as superabundance in that respect. If you're ever writing a report, be sure to put those two words in it. Also, speak truth to power and perfect storm. Try to put two or more of those in a single sentence, e.g. "It takes a brave man to speak truth to power against the Keynesian superabundance that has created a perfect storm". I digress.
In general, back in the day, Olympus sold two and sometimes three lenses in each focal length; slow and cheap, fast and expensive, and sometimes very fast and very expensive, as in the case of the 21mm f/2 or the super-effective 350mm f/2.8, and sometimes very slow and much cheaper, such as the 21mm f/3.5 or the 135mm f/3.5. Or for that matter the 28mm f/3.5, which is the subject of this post. They hover around £40 or so on eBay. The f/2.8 version sells for almost the same; it's more common, and the f/3.5 version has a bit of hype behind it. My gut instinct was that the slower lens would be sharper, because it isn't so highly-strung, although in practice it still needs to be stopped down for optimal performance. That said, it's no great sin to judge an f/3.5 lens at f/8, whereas it would be folly to emphasise the f/8 performance of a much faster lens. The f/3.5 is a carthorse, designed to pull things, whereas faster lenses are supposed to be sexy.
The f/3.5 was the standard budget wide angle for the first half of the OM system's life, during its most popular period, in the late 1970s and early 1980s, and so there are loads available on the used market. Furthermore it has a very conservative specification. The 28mm focal length in general is wide but not eye-popping. Almost all standard zooms and most compact cameras have a 28mm setting - many even start at 24mm - and the chances that you don't already have a 28mm equivalent lens are very low (for crop-sensor cameras, it is the equivalent of a 17mm, 18mm kit lens). The 28mm f/3.5 isn't any faster than a kit lens. Some compact cameras even have faster, wider lenses. On a crop-sensor camera it becomes a very slow 44mm normal and doesn't make a lot of sense.
However, I don't have a crop-sensor camera. I have a full-frame camera, and I am always on the lookout for a full-frame wide angle lens that is sharp to the extreme corners at f/8. There are lots of full-frame 28mm lenses; not many of them are sharp to the extreme corners at f/8. The Canon 28mm f/2.8 I briefly owned wasn't and had a lot of CA. Surprisingly, the Carl Zeiss Contax 28mm f/2.8 Distagon wasn't either - it was hella sharp, just not in the extreme corners. That disappointed me a bit. Is the 28mm f/3.5 sharp to the etc? Let's find out.
Once more I venture to the piss-stinking, visually cancerous Culver Street car park, Salisbury, because it has sharp edges. Ten points if you can spot the used needles and used latex gloves in the images that follow. Here's what the vignetting looks like at f/3.5 (a fair amount) and then f/8 (not so much), shot with a 5D MkII:
Here's the bottom-right corner at f/3.5, no unsharp mask, with the contrast boosted so that you can see the wall clearly (this explains why there's noticeable chroma noise); click for full-size:
It's soft but at least consistently so. Compare with the same subject shot for my review of the Canon 28-70mm f/3.5-4.5 MkII, particularly the 28mm f/2.8 at f/8, which is sharp almost to the extreme corner but goes fuzzy in the last little bit. Here's the 28mm f/3.5 at f/5.6:
It's sharper but could be sharper still. And here it is at f/8:
It's sharp indeed, noticeably better than the Canon 28mm f/2.8 and the Canon 28-70mm f/3.5-4.5. With unsharp mask it actually becomes unnatural-looking, viz:
A Canon 24-70mm f/2.8 might well be sharper, and for £970 I should damn well hope so. The Olympus 28mm will however fit in a shirt pocket, which cannot be said of the 24-70mm. I have also heard good things of the manual focus Nikon 28mm f/2.8 AIS, but that will have to be another post, another day. The Olympus 28mm f/2.8 is also apparently good, but is it better than the f/3.5? I will have to find out.
For the sake of completeness, the image quality doesn't get any better f/11 and becomes slightly but noticeably softer at f/16, the narrowest aperture. I focused and shot with Live View, and used timed delay and a well-braced Gorillapod. Here's the full-size file at f/8, shot with a full-frame 5D MkII, converted with Canon Digital Photo Professional, sharpness +2 (click):
And here's a further comparison, taken from the right edge of the frame, f/3.5 at the top and f/8 at the bottom, auto-contrast. The f/3.5 image has a blurriness about it, although to be fair I can't actually see any more detail in the PRIVATE PARKING sign on the f/8 shot, it just looks sharper:
Here's what the CA looks like uncorrected at f/8:
It's not particularly visible in this worst-case scenario, and can easily be corrected with software. Here's a shot taken from the centre of the frame, at f/8, with unsharp mask:
I usually have a magic unsharp mask setting of REDACTED, but for this shot I toned the settings down a bit. The 5D MkII's files benefit from relatively aggressive sharpening but my secret settings were too sharp.
Conclusion and limitations
My conclusion is that the 28mm f/3.5 is sharp across the frame at f/8 on a 21mp Canon 5D MkII, and when corrected for CA, with unsharp mask applied, the image quality is definitive. That's all I ask for.
The 28mm f/3.5 has some limitations. It's really a bright daylight lens. At f/3.5 the viewfinder gets very dark in low light, especially if you are using a polarising filter. Live View is a godsend in this respect, but once you go indoors you will curse the lens. Furthermore, with a relatively narrow aperture, you will struggle to create narrow depth-of-field effects. On a more tangental level, the combination of narrow aperture and conservative focal length has the effect of nullifying some of the rationale behind carrying a large, bulky full-frame SLR; if you have to shoot at ISO 800 all the time, and all your images are sharp across the frame with near-infinite depth of field, you'll start to wonder why you didn't use a Micro Four Thirds camera instead.
It is often opined that a full-frame camera is a money sink, because the only good full-frame lenses cost a fortune; this is not the case if you're prepared to put up with manual focus and you can do without f/2.8. A kit consisting of the Olympus 28mm f/3.5, 50mm f/1.8, and an OM-fitting Vivitar 70-150mm f/3.8 will go a long way and will cost less than a hundred pounds. God bless thirty years of depreciation. Depreciation has hit the OM surprisingly hard. It never had a romantic element; it never had a mythos, it was too new and modern for legends to grow around it, and it was never sent into the world's warzones and trouble spots. As a consequence the lenses are reasonably priced on the used market, because they haven't been hyped up by passion. A few still command a high price on account of their still-impressive specification; the 21mm f/2 mentioned earlier, and also a late-period 35-80mm f/2.8 zoom.
I can only find one proper test of the 28mm f/3.5, at SLRLensReview, here. They come to the same conclusion as me, and they go on to point out that the 28mm f/2.8 and 28mm f/2 are very similar in the same aperture range. The 28mm f/2.8 is fairly common and is probably the best option of the three 28mms, so if you see one cheap, snap it up.
NB In common with most other old manual lenses, the OM system can be adapted easily to Canon's EOS SLRs with a simple metal ring. Olympus sells an OM adapter for the Four Thirds / Micro Four Thirds system, albeit that this incurs a 2x focal length multiplier (you'd be much better off buying the Panasonic 20mm f/1.7). Judging by this handy table of lens registration distances, an OM-Sigma SA adapter might be possible assuming the SA mount is physically large enough.
Apart from that, any adapters would have to involve an optical element on account of the different lens registration distances. There is an OM-Sony Alpha adapter which works on this principle although it is apparently only suitable for telephoto lenses if you use a full-frame Alpha. I have never seen a Nikon-OM or Pentax-OM adapter. I surmise that you'd have to dismantle and modify either the lens or the camera mount to fit an OM lens to these systems, and it wouldn't be worth it. Nikon and Pentax both have a rich legacy of old primes, stretching back decades. As a Canon user, part of the appeal of lenses from the distant past is that the EOS system doesn't have a rich legacy of old primes; it only goes back to 1987, a time when plastic zooms were in the ascendant.
Since writing the above I bought a Tamron 28-75mm f/2.8, which seems to get good reviews. In my experience it's sharp in the middle at f/2.8 and decent in the corners stopped down, but the Olympus 28mm is sharper. On an APS-C camera it would be very good, albeit with the same odd range as the Canon 28-70mm f/3.5-4.5 I wrote about earlier in the year. Unlike the Canon lens it's usable wide open, and so at 75mm, f/2.8 (roughly 120mm in APS-C terms) it would be handy for portraits, and indeed it seems to be very popular for this reason. Paired with (say) a Sigma 8-16mm you'd have a good general-purpose APS-C kit, with a bit of a gap at the moderate wide end. It focuses very closely as well.
I did a rough comparison by pointing the camera out of a window, hand-held. Here's the scene:
Here's the middle of the frame, Tamron at the top and Olympus at the bottom, both at f/8, a 100% crop with the same 0, 0.5, 150 unsharp mask setting and the same daylight colour balance (but no corrections for distortion or CA):
They're basically the same. Here's the edge of the APS-C frame, Tamron at the top and Jack Palance at the bottom:
They're very similar, although the Tamron lens has more CA and isn't quite as sharp as the Olympus lens (which also has some CA, but not as much). Here's the extreme bottom-right corner, Tamron at the top and Olympus at the bottom:
The Tamron lens puts up a valiant performance but gives up at the extreme corner, at least in terms of resolution. For a zoom lens it's not bad; distortion is low and the colours are nice. The Olympus lens resolves more detail but the colours are a bit washed-out, although this can be corrected with software. And it has to be said that in real life, when sized down or printed out, people aren't going to care that a tiny patch in the extreme corners is blurry. Unfortunately this isn't real life any more. It's 2010, we've moved beyond that.
Here are some pots, just to the left above the above crop:
Again the Olympus lens resolves more, but the Tamron lens is close behind. I surmise that on an APS-H camera it would also be pretty good, if you happen to have an old Canon 1D lying around doing nothing.