Using Lens Adapters

When you’ve made a significant investment in camera bodies and lenses from a particular manufacturer over a long period of time, there’s little incentive to swap to a different brand. Most serious photographers have pondered the pros and cons of swapping when the manufacturer of a different brand from the one they use releases a particularly attractive camera body. In the main, however, inertia kicks in and they stick with their current brand – even at the cost of reduced shooting versatility.

Many of us also have older lenses that don’t fit on existing DSLR bodies or come from different manufacturers. Discussing this with a photographer friend, who has a collection of old Leica lenses but uses Canon bodies, we decided to investigate the use of lens adapters with modern DSLRs. In the course of our research, we tried out 30+-year-old Leica and Nikkor lenses on current Canon bodies.

Lens Adapters
A search in good camera shops or on EBay will reveal a number of lens adapters at varying price points and widely differing qualities. Some are relatively simple units with no electronic contacts, while others come with AF-confirm chips that support focus confirmation and may also support some metering modes.

Although the latter may appear to be easier to use, they’re more difficult to obtain locally and you will probably need to fine-tune both parameters (focus and exposure) manually before you get good results. Several problems have also been associated with chipped adapters:

1. Because the chips are glued into place, they may interfere with the mounting plate and can protrude into the mirror box.
2. If the glue isn’t properly applied, they may also fall off into the mirror box!
3. They may not provide really accurate focusing – although they will probably come reasonably close.

The adapters used for this report were produced by Novoflex and distributed locally by Mainline Photographics (www.mainlinephoto.com.au). Novoflex offers adapters for fitting Leica and Nikon (Nikkor) lenses to Canon EOS bodies and adapters for fitting Leica R, Olympus OM and Pentax K lenses to Four Thirds System camera bodies. Interestingly, it’s quite difficult to find adapters for fitting other manufacturers’ lenses to Nikon or Sony bodies – but that may just be a matter of time.

Adapter prices range from just under $250 for Four Thirds System adapters to $309 for the Canon adaptors. Novoflex is also planning Micro Four Thirds adapters for Leica R (the SLR lenses), Nikon, Contax/Yashica, Olympus, Pentax and Minolta lenses. However, we don’t know when they will be available.

Limitations
Adapters can only be used with some lenses, usually those with more ‘modern’ mount designs. They won’t work with very old lenses that have protruding tabs, such as older non-AI Nikkors and Leica lenses. You must also avoid lenses with rear elements that protrude into the mirror box of the camera, such as some ultra-wide-angle lenses. You can damage the camera’s mirror if clearance is too tight.

Before buying an adapter, it’s important to understand the limitations it places on your photography. For starters, adapters aren’t covered by the camera’s warranty so you use them at your own risk (and any damage they cause is your responsibility). In addition, most adapters will require you to to use your DSLR camera in manual mode. This means:

1. Autofocus (AF) is not available. Manual focusing is required for all shots and the viewfinder screens in some DSLRs are not easy to use for manual focusing (split-screens are the most accurate).
2. Stop-down metering (ie, metering at the shooting aperture) is required and this can make the viewfinder quite dark. Most metering modes should be usable, although spot metering can’t be used with some adapters. Shutter speeds must be set manually.
3. A few adapters may allow you to use the aperture-priority AE mode. However, there is no automatic stop-down and the aperture probably won’t be displayed in the viewfinder or on the camera’s LCD monitor and/or data panel.
4. The distance scale on some lenses may not indicate the actual focusing distance. Always use the viewfinder for focusing.

Depending on the age of the lenses you wish to fit, you may also find the range of apertures supported is somewhat restricted. In our tests, the Leicaflex 35mm Summicron lens’s aperture range went from f4 to f16, while the Reflex Nikkor 500mm lens was fixed at f8. In neither case did the restriction place any significant limitations on actual picture-taking. However, compared with modern lenses, both lenses offer fewer adjustments.

Shooting with an Adapter
Fitting lenses from different manufacturers to your DLSR body requires a completely different approach to taking pictures. Because all shooting parameters must be set manually, your shooting sequence operates as follows:

1. Set the lens aperture to wide open while you focus on the subject.
2. Calculate the correct exposure for the ISO setting you wish to use. (If you don’t have a hand-held exposure meter, a rule-of-thumb guide to determining correct exposures is provided below.)
3. Set the shutter speed, then stop the lens down to the desired aperture setting. If metering is supported, take the exposure measurement at this point.
4. Shoot.
5. Check the image, using the histogram display to see whether the exposure is correctly positioned. If not, adjust aperture or shutter speed, re-shoot and check again.

In our tests we found the camera’s live view mode could be handy for focusing the camera with the older lenses. It was often easier than using the viewfinder because standard viewfinder screens have been designed for AF lenses and don’t provide enough clarity for manual focusing. Live view systems that let you magnify the image make manual focusing simpler and more accurate. Where interchangeable viewfinder screens are available, split-screens are much faster and easier to focus than most other types.

Comparison Tests
While you can certainly justify acquiring an adapter to let you use special lenses that are no longer manufactured – or lenses that have never been offered for your camera mount – in situations where the focal length and aperture range offered by an older lens is covered by a recently-released lens that’s designed for your camera, it’s more complex. Essentially you need to weigh up the possible quality advantages of the older lens against the convenience and greater versatility of new optics.

To demonstrate just how difficult this decision can be, we ran parallel tests at the same 35mm focal length, comparing the Canon 24-105mm f4L IS USM and Canon 35mm f1.4L USM lenses with a Leicaflex 35mm f4 Summicron lens that’s roughly 30 years old. All tests were run using the new EOS 5D Mark II camera body. The results are shown in the graphs on this page.

Results of Imatest testing for resolution show the Leicaflex lens has a flatter field across its aperture range than the other lenses but is unacceptably soft at wide apertures. Its ‘sweet spot’ is between f8 and f11, where it is better than the Canon prime lens. The Canon zoom lens suffers from edge softening right up to its ‘sweet spot’ at f11 (which is slightly higher than the other lenses), while the Canon 35mm prime lens is the best performer across the aperture range.

Imatest showed lateral chromatic aberration to be negligible for all three lenses, except at f4, where the 24-105mm zoom nudged into the ‘low’ category. (The yellow line marks the border between ‘negligible’ and ‘low’.)

Conclusion
We were unable to discern much difference in actual photographs of the same subject taken from the same position with the three lenses and they didn’t show up in A3-sized prints. So, unless you have an old lens you really love – or a lens with special properties like our Reflex Nikkor 500mm lens – choosing the adapter route is probably not worth the hassle.

However, adapters come into their own when the older (or different-branded) lens provides more in the way of resolution, edge-to-edge sharpness or some desirable property. They provide a great way to enable you to continue shooting with a special lens and getting shots like the ones shown on these pages.

The Reflex Nikkor 500mm lens on the Canon EOS 400D body provides a focal length equivalent to 800mm, which is great for action shots. The ‘doughnut-shaped’ highlights on out-of-focus areas are characteristic of mirror lenses.

The Reflex Nikkor 500mm lens on the Canon EOS 5D Mark II body retains its designated focal length. Note the slight corner darkening that also characterises mirror lenses.

A close-up taken with the Reflex Nikkor 500mm lens on the Canon EOS 5D Mark II body shows the shallow depth-of-field and beautiful bokeh that has made this lens a long-time favourite.

On any DSLR body, the Reflex Nikkor 500mm lens is ideal for bird photography.

Determining Exposures
When you can’t use the camera’s metering system you need a quick and easy way to bring you as close as possible to the correct exposure levels. Some fine-tuning will often be required to cover the brightness range of most subjects but the following rule-of-thumb should be quite effective. At an ISO setting of 100 and shutter speed of 1/125 second, use the following aperture settings in the following lighting conditions:

– Direct sun on snow or sand: f22

– Bright or hazy sunlight with noticeable shadows: f16

– Weak, hazy sun with visible shadows: f11

– Diffuse light under thin clouds with no obvious shadows: f8

– Heavy overcast without shadows: f5.6

– Open shade, sunrise or sunset (when the sun is rising): f4

– Landscapes just before sunrise or after sunset: f2.8

– Night in brightly-lit conditions (cityscape or sports stadium): f1.4

– Under dense rainforest canopy: f1.0

– Fireworks: f0.25

– Full moon without any other lighting: f0.125

Note: where the listed aperture settings are not supported, compensate by reducing the shutter speed by one or more f-stops and/or increasing ISO sensitivity by one or more steps.

Also see More Lens Adaptor Options