OM*

My new full frame Olympus with the Olympus OM Zuiko 50mm f1.4 lens mounted on a Fotodiox adapter.

Well I’ve done it. I’ve gone full frame digital with Olympus. No I’ve not got access to some top-secret prototype from Olympus. Instead I’m mounting OM Zuiko lenses on a “full frame” (I hate that term, I much prefer 35mm sensor) camera digital – the Sony A7r to be precise – with a Fotodiox pro OM-NEX adapter.

“If you date your cameras, you marry your lenses.”

David Hobby

Sony A7r with Olympus 24mm, 35mm and 50mm lenses. The Fotodiox Pro OM to Nex lens mount adaptor allows them to be mounted to the camera.

I was left with a collection of Olympus OM lenses when Olympus in their infinite wisdom decided to abandon the OM mount – this did not occur with the advent of digital imaging, but back in the film era. I migrated to the Canon EOS system reluctantly and left my lovely jewel like Zuiko lenses sitting in a drawer. Every now and again I would get one out and fondle it. Oh the beautiful feel of the buttery smooth focusing ring with its long throw. The cool feeling of the metal body with that heft that instantly denotes high quality precision engineering. To cap it off and send me into a rapturous state is the aperture ring – firstly there is one, and then there is the feel and sound of that ring as you change aperture. Just thinking about sends me into the throes of ecstasy.

Now it is a little known fact that when Yoshihisa Maitani designed the OM system he chose to make the flange distance a mere 46mm. At the time he probably thought that this would make a very compact SLR. But the unforeseen benefit of this decision is that it makes the OM lenses very easy to adapt to other cameras. Indeed when Canon brought out the ground breaking EOS 5d I was aware that you could buy an adapter to fit Olympus lenses to the body. But the experience was to me somewhat dismal. DSLRs really aren’t made to use manual lenses. It’s like expecting to find meat in a chicken McNugget. A disappointing experience. When Panasonic and Olympus announced the birth of micro four thirds in 2008 one of key features was the jettisoning of the mirror box found in SLRs. This has a couple of benefits. Firstly it means that a much shorter flange focal distance can be used. In ordinary speak this is the distance between the sensor/film plane and the lens mount on the camera body. Micro four thirds has a distance of 19.25mm which meant it was ideally suited to adapting lenses. I talked about this in April 2013 and again in April 2016. The second benefit was the provision of focus peaking. Focus peaking had long been found on video cameras by dint of them having an electronic viewfinder, it was quickly added to the feature list of mirrorless cameras. I first used it with the EM10 and was very happy with it. But there was a fly in the ointment. My carefully considered lens collection had been altered by virtue of the crop factor, basically a 50mm lens on m4/3 gives an angle of view equivalent to a 100mm lens on a 35mm sensor. Bugger! So apart from video use I put the old lenses away again.

A little while later Sony heralded the launch of their A7 series of full framed mirrorless cameras and initially my interest was piqued but the reality of buying into another camera system (I was already running Olympus m4/3 and Canon EOS) was just not an option. So I feigned disinterest. But an interesting thing happened, Sony update their models with incredible speed and that meant the prices of second-hand A7 and A7r dropped faster than an Essex girl’s knickers. All of a sudden my beautiful OM lenses were restored to their full frame glory.

 

Olympus OM Zuiko 50mm f1.4 at f8.
Olympus OM Zuiko 50mm f1.4 at f8.

To test the lenses I shot a standard scene which was composed of a book shelf in my sitting room. Mounting the camera on a tripod I then framed up so that the complete height of the shelf filled the frame. The shots were taken wide open and then stopped down to f8. To see more detail in the test shots just click on the image and it will open in a new browser. This will be an evolving series of articles about using various OM lenses.

 

Olympus OM Zuiko MC 50mm f1.4

 

Olympus OM Zuiko MC 50mm f1.4

The first lens most people whack an adapter on is a fast standard. The 50mm f1.4 was one of the original lenses that was introduced when the OM system was launched at Photokina in 1972. The original silver nosed (a term referring to chromed front mount ring) had a single lens coating and was 36mm in length.The newer MC version was introduced in 1984. Along with the new improved lens multi coating the design was changed resulting in a length of 40mm with a weight of 280g. The lens construction is seven elements in six groups. Despite being a fast lens it has a modest size and has a 49mm filter thread.

50mmf14optic

 

Shooting my test subject one of the very first things I noticed is that the image displays very slight barrel distortion. This is where image magnification decreases with distance from the optical axis and makes parallel straight lines look like the edges of a wooden barrel. This phenomenon is usually associated with wide-angle prime lenses or the wide end of standard zooms. It does happen in standard primes lenses but usually only at close focussing distances so it was surprising to see it here. Wide open lateral chromatic aberration (CA) is perceptible and at f8 cannot be seen. In terms of sharpness at f1.4 the image is universally soft and lacking in contrast. Stopping down to f8 improves the image and the lens is sharp across the frame. The lens renders beautifully with a gentle fall off in tones and the bokeh is a delight being soft and smooth. The lens is quite resistant to flare and I haven’t felt any great need to put on a lens hood.

olympus-50-cpmparison-1

A street sign on Avon Terrace in York, Western Australia. Taken on a Sony A7r with Olympus OM Zuiko 50mm f14. Shot at f1.4.

 

Al fresco at Henry Saw in Grand Lane in Perth WA. Olympus OM Zuiko 50mm f1.4

In conclusion – well I always thought that it was a very good lens when I shot film and now having had the opportunity to mount it on a high megapixel digital camera I am not disappointed. If adapted lenses are your thing I would definitely recommend you to acquire a copy.

 

* today’s musical reference is to the Moody Blues the pioneers of art rock and progressive rock.

Equivalence Schmalivance

Comparing the sizes of full frame, APSc and m4/3 cameras and lenses.

Internet forums are full of self-proclaimed experts spouting absolute crap about things they know nothing about. Unless you were hiding out in a cave with Osama Bin Laden or not visited the home of countless pointless photographic brand based crusades that is otherwise known as dpreview.com you maybe aware of this hot topic that has spawned a thousand fevered posts and countless character assassinations. If not it goes like this: equivalence is the idea that the size of the camera format effects focal length, depth of field, and exposure, and that when talking about equipment one should express this in terms relating to 35mm equivalents. These arguments became particularly prevalent when Olympus and Panasonic started to have some success with their micro four thirds format. The people express this idea most fervently are those who have sold two of their children and a kidney on Ebay to fund the purchase of a so-called full-frame dSLR and they want to let everyone who uses a smaller format that they are using an inferior product. Usually these arguments go like this:

m4/3 user: Hey I’ve just got my self a new lens, it’s the Olympus 45mm f1.9. It’s a lovely lens, wide open it produces very portraits wide open.

Full framer: It’s not a 45mm f1.8 it is a 90mm f3.8. It cannot render out of focus backgrounds and the smaller sensor needs more light and therefore longer exposures or higher ISO. A proper photographer would use an 85mm f1.2 on a full frame camera.

The argument will typically degenerate and lead to insults and other full frame users diving in to bolster the argument with lots of spurious mathematical equations, graphs and claims of mental deficiency on the part of any smaller format user and maybe even casting doubts on the mental faculties of their parents as well. So what is all this about then and why are people getting so hot under the collar?

Equivalence is not a new thing, it didn’t come with digital, it was a known fact back in the dim dark ages of film, and then funnily enough 35mm film was seen as the miniature inferior format. In those far off times a lot of professional work, and when I use the term professional I mean done for money, was shot using large format, the smallest was 5×4 inches and the largest practical was 10×8 inches. The next step down was medium format where a roll of film was used that was nominally 6cm wide, the popular sizes were 6×7, 6×6 and 6×4.5 cm. Small format, or miniature format was 35mm and smaller. It wasn’t until the advent of modern electronics  and a significant breakthrough with tabular grain film  in the 1980’s that 35mm really took off as a format. The ease of use that automation made with sharper finer grained films that made many professional photographers and advanced amateurs take up using 35mm and by the end of the 1990’s the larger formats had become niche products for specialised uses.

Professional photographers were well aware of equivalence.  A 10×8 camera with a 300mm lens has the same angle of view as a 5×4 camera with 150mm, a 6x6cm camera with 80mm and a 35mm camera with a 50mm. As most working photographers ran more than one format and some three or more favourite angles of view would be duplicated across the systems. So for 5×4 a photographer may have a 90mm, a 150, and a 300. His/her 6×6 system would then have a 55, 80 and 150mm lenses, and the 35mm system  35, 50 and 100mm lens all giving roughly the same angles of view.

Factors that influence depth of field are:

  • format size
  • focal length
  • distance to subject
  • magnification
  • lens aperture

From this we can, therefore assume that the larger the format size , the longer the focal length, the closer to the subject, the larger the lens aperture, and the greater the magnification the less the depth of field. So that is clear then. Well no because when we talk about depth of field it is also important to remember that what we are really talking about is acceptable sharpness because a lens can only render one single distance in focus (the plane of critical focus) and objects at other distances to the front and rear will have diminishing sharpness the further they are away from that point. The reality of this is that for most normal usage part of the scene will be acceptably sharp both in front of and behind the point of critical focus, and this zone will be formed that 1/3 of it is in front of the subject and 2/3 behind. This zone can be shallow with only a small part of the scene appearing to be sharp, or it can be deep with the apparent sharpness seemingly covering everything. Seems simple so far, well it gets more complicated because you can break these relationships. As magnification increases the depth of field decreases and the zone of apparent sharpness also shifts from the one-third in front and two-thirds to the rear to an equidistant amount front and rear. Also once you start playing with the plane of the lens in relation to the sensor and subject then everything can go a bit strange. Typically one of the problems that plagued large format shooters was that of getting enough depth of field. Large sensor, small depth of field, not much chop if you’re a landscape shooter. Well using the Scheimpflug rule you can place the plane of focus wherever you want in a scene by positioning the plane of the lens to be parallel with the plane of the subject by tilting the camera front, if that does not completely achieve what you want then you tilt the sensor plane as well  so that the planes of the subject, lens and sensor form an intersecting point and this will mean that the subject plane will then be completely sharp while shooting wide open. Working the other way round you can diminish the zone of sharpness  by swinging and tilting the camera front. This is not the sole prerogative of large format camera, tilt and shift lenses are available in medium format, 35mm, APS and even m4/3 . The other thing that throws a spanner in the works for depth of field is that the size of the output and viewing distance plays a big part. Simply put big print viewed at a distance and apparent sharpness is reduced.

12mm .v. 24mm

To test the theory I decided to print out an A3 sized lens resolution test chart and this was then set up on an easel in my garden. A tripod was then set up 1.8 metres away from the easel. The cameras tested were the Olympus EP-2 and the Canon EOS5d, both having roughly the same number of megapixels. Choosing lenses was somewhat problematic although I have a set of professional grade fast aperture constant zooms for my 5d I don’t for the EP-2. The lenses used were for the Canon an EF 24mm f2.8, a Sigma 105 f2.8 macro and  an 75-300mm f/4-5.6 IS USM. For the Olympus the lenses were a Zuiko 12-50mm f3.5-6.3, a Zuiko 60mm f2.8 macro, and a Zuiko 40-150mm f4-5.6. Each camera was mounted on the tripod in turn and set to shoot large quality jpegs in aperture priority, image stabilisation where appropriate was switched off and the self timer was used to prevent any camera shake. The lens was focused on the chart. None of the images have been processed in any way and the full-sized images can be seen by clicking on any of the composite shots below where you’ll be taken to my Flickr account. At the 24mm and equivalent view the DOF was pretty much equal, although I suspect that there maybe more apparent differences at apertures of f2 and wider, but I wasn’t able to test that. The comparison between the two short telephoto macro lenses highlighted the most difference and at wide open at f2.8 the Olympus manages to resolve some background detail while the Canon doesn’t at all. At the equivalent of 300mm at f5.6 there is very little discernible difference, but that changes at f8 and smaller where the m4/3 camera starts to resolve more detail.

Zuiko 60mm .v. Sigma 105mm
150mm .v. 300mm

So what happens to exposure. Doesn’t that change? The short answer is no. When I got my first medium format camera, a secondhand Mamiya C330 Professional , it had no built in metering and the  handheld Weston meter that came with it had obviously been dropped and no longer worked properly so I used my Olympus OM1n  as a meter and guess what? It worked! Much later when working in the studio with studio flash I determined the exposure with my flash meter and would often make exposures with different format cameras but the exposure value remained the same and the images were correctly exposed. Memory is a fine thing, but I wanted to make definitely sure so I decided to run a quick test comparing full frame, to APS-c, m4/3 and compact camera with a sensor measuring 8.07 x 5.56 mm. The test was simple each camera would use a lens of as near as possible field of view equivalent to 105mm on full frame. The ISO was set to 200, and the shutter speed was set to the maximum synch speed so as not to let ambient light interfere with the result. White balance was set to flash, and pictures settings were natural and the images recorded as fine jpegs. A Canon 550EX speedlite was mounted on a light stand, set on manual to 1/2 power and fired at the test scene through an umbrella diffuser and was triggered by a synch cord. The flash output was measured with my Minolta flash meter which is accurate to 1/10 of a stop, the aperture required for correct exposure was f7.7, each cameras lens was set to the nearest corresponding value which was f7.1. All images are straight out of the camera without any processing. Each cameras image was opened up large in Lightroom 3 and screen shot was taken of the image showing the histogram. Looking at the histogram shows that there’s barely any discernible difference between each cameras recording of the scene.

Canon EOS5d
Canon EOS550d
Olympus EP-2
Panasonic Lumix LX5

So what does all this mean? Well the full framer is right in that a 45mm lens on m4/3 does have an angle of view equal to a 90mm on a 35mm sensor. As to the inability to have shallow depth of field that is wrong, it is definitely possible to minimise depth of field but we are talking about subjective differences here as there is that nebulous term “acceptable sharpness” and then it depends on how big you print, and how close you are when you view it. Personally when I take a head and shoulders portrait of someone I like to have from the tip of the nose to the ears in focus as I like to be able to see who I’m looking at. Shooting at 85mm f1.2 the depth of field can be measured in millimetres and so the iris of the eye might be in focus but the rest is just blur. This is just a matter of taste. If you were shooting landscapes using wide-angle lenses then there is little to choose between m4/3s and full frame, and in fact I might go as far to say that the smaller camera has the advantage being smaller and lighter. As to the matter of the smaller format needing more light to form an image that is just plain wrong.

So is the 35mm dSLR superior to m4/3? Yes and no. Infuriating aren’t I! It all depends upon your photographic priorities. If you want to squeeze every last ounce of image quality out of a scene then 10×8 or whole plate large format film cameras either contact printed or drum scanned cannot be beat. Hopeless though for getting shots of the rug rats playing at the park, expensive to run, not very portable and definitely not conducive to spontaneity. Want something you take anywhere and be able to upload images to the web, well your phone cam is your best bet. My Olympus EP-2  is my favourite go anywhere camera. I can rig it up to be like a dSLR by adding its optional electronic viewfinder when I want to use a long lens, put on the 17mm f2.8 pancake lens and it fits in my jacket pocket, put on a mic,  a loupe, put it in its cage or rig and its a great little video camera. It perfect for lightweight travel. Out walking the dog or shopping then chances are I’ve got my Panasonic LX-5. My Canon EOS5d  is the original 13Mp version and I still keep for certain things and for certain lenses that I just don’t want to give up. There are no absolutes, pick your camera for what you need not what other people think that you should use.