If you don’t already know what a legacy lens is, it’s a lens from a previous camera system (i.e. film camera lens), which is now defunct but can be adapted for use on a modern digital camera system. For example, if you have an old 50mm manual focus Olympus OM lens you can buy a lens adapter and use it on your digital micro 4/3rds camera. Lens mount adapters are available for almost all legacy 35mm film camera lenses so they can be converted to fit micro 4/3rds cameras. This is one of the key appealing features of the micro 4/3rds camera system.

An old manual focus lens will not have any electronic contacts to allow it to be controlled from the camera nor will it have autofocus so will have to be controlled manually. The aperture is changed via the aperture ring on the lens barrel and focus is achieved by manually turning the focus ring. You'll want to use the magnifier function on your camera to aid focusing. Alternatively, if your camera has focus peaking like the new Olympus E-P5 you can enable this feature to aid accurate manual focusing.
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| Olympus E-P3 with Pentax M 50mm f1.4 including adapter |
Why use an old 50mm manual focus lens
What is immediately noticeable with old manual focus lenses is the build quality. Often made from metal, unlike their modern plastic equivalents, they look and feel beautifully crafted and the mechanical implementation has a sublime action with a focus ring resistance that’s silky smooth. These lenses will have markings on the lens barrel for the focus distance; depth of field scale and aperture f-numbers that make them look very professional by today’s standards. They just simply feel luxurious in the hand and will make you want to use them over and over again despite being technologically primitive.
One thing about these lenses that’s not considered primitive is the high quality of the glass optics. A 1970s 50mm f1.4 lens would have used the best glass available at the time and include at least 8 aperture blades for smoother rendition of the out of focus areas of an image. A 50mm f1.7 on the other hand is the cheaper relation to the f1.4 and whilst not constructed with the same high quality materials or glass elements, it's still made well. It will have good optics but usually have only 6 aperture blades and the bokeh will be less developed. That said, it’s sometimes the case that an f1.7 maybe slightly sharper than an f1.4 at maximum aperture.
So what does this all mean? It means that a 35 year-old 50mm lens is capable of high quality results on modern digital cameras at a very low cost.
50mm legacy lens on your Micro 4/3rds camera
The 50mm lenses being discussed here were designed for 35mm film cameras. The size of the 35mm film format is approximately double the size of the micro 4/3rds format. This means that used on a micro 4/3rds camera, the 50mm lens field of view is now equivalent to 100mm on the 35mm format (50 x 2 = 100). This turns the humble 50mm lens into a classic portrait lens focal length for a fraction of the price and gives a new lease of life to these old-timers.
Using the photo of the Morris dancers, I've attempted to illustrate that when a legacy 35mm format lens with a focal length of 50mm is used on a micro 4/3rds camera, the field of view will change, effectively mimicking the field of view of a 100mm lens. This is what is referred to as the crop factor, or in the case of micro 4/3rds, the 2x crop factor. The 2x crop factor follows with any 35mm format lens, so a 100mm lens has the same field of view as a 200mm lens when used on a micro 4/3rds camera.
The image below is just a visual representation to aid understanding, so the aspect ratio, scale and format should not be interpreted as accurate.
Click on images for larger view:
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| For illustrative purposes only |
The micro 4/rds format is smaller and therefore has a narrower field of view with approximately 50% of the 35mm format image filling the micro 4/3rds frame. It’s effectively zooming in on the scene and acting like a 100mm telephoto lens.
A very appealing aspect of a 50mm lens on a micro 4/3rds camera is the shallow depth of field capabilities and the bokeh (blur) it produces. This is where a 50mm f1.4 does not disappoint. Used wide open at f1.4 images may look soft and take on a dreamy ethereal appearance, which is common to many 50mm f1.4 lenses. Stopping down to f2.0 sharpens things up a little but stopping down to f2.8 will produce impressively sharp images with great clarity whilst maintaining a shallow depth of field.
I generally shoot at f2.8 with my 50mm f1.4 as I think this aperture produces a good balance between sharpness, clarity and shallow depth of field for subject isolation. Of course, in the cases where shallow depth of field is not what I want, stopping down to smaller apertures produces excellent sharpness throughout the frame. Also, if you do shoot at an aperture faster than f2.8 you’ll need a steady hand or a tripod because the depth of field is very shallow and any movement will shift the focus point and throw the subject out of focus.
This is not intended to be a technical review but just an informative guide from a user perspective.
Let’s have a look at some photos taken with my old Pentax M 50mm f1.4 on my Olympus E-P3. All photos have been converted from RAW to JPEG with no sharpening applied.
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| 50mm @ f2.8 |
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| 50mm @ f2.8 - Me taken by Anna |
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| 50mm @ f2.8 |
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| 50mm @ f2.8 |
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| 50mm @ f2.8 |
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| 50mm used as telephoto lens - Trellick Tower, London |
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| 50mm @ f2.8 - Very shallow depth of field |
Old 50mm lenses generally don’t have circular apertures therefore out of focus highlights will take on the octagonal shape of the aperture blades, as can be seen in the picture below.
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| 50mm @ f2.8 |
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| 50mm @ f4 |
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| 50mm @ f2.8 |
Old manual focus legacy lenses and lens mount adapters are available from many camera shops and of course Ebay. When buying a lens mount adapter be sure to get the correct one for your camera as it can be easy to make a mistake where a brand has had more than one lens mount. For example, if you want to use your old Olympus OM lenses on your micro 4/3ds camera you'll need to get an OM to M4/3 adapter, not OM to 4/3rds, which is different lens mount. If in doubt, ask the retailer for the correct one for your camera and lens combo.
Legacy manual focus lenses are a joy to use and will improve your understanding of aperture f-stops as well as focusing techniques. They give your kit a quality, high-end feel and are capable of great results.
Pick one up with an adapter now and you'll wonder why you hadn't done it sooner.