Adaptation of manual focus lenses

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An adapter is a metal tube or ring with a mount that matches your camera on one side and a mount that matches your lens on the other. By the means of the adapter you can use a lens from different system on your camera. First, you attach the adapter to the lens, and then you attach them to your camera - just like any lens specially designed for your camera. However, this requires that the flange focal distance of the lens mount is equal to or greater than the flange focal distance of the camera mount. The flange focal distance is the distance from the mounting flange to the film or imaging sensor plane. The greater the difference in flange focal distances, the thicker the adapter.

Flange focal distances of modern digital SLR cameras, and POPULAR SLR lens mounts that can be adapted to them:

Camera seriesFFD, mmAdaptable lens mountsTotal
Nikon46.5Leica R1
Pentax45.5Contax/Yashica, Leica R, M42, Nikon F, Olympus OM5
Sony DSLR/SLT44.5Contax/Yashica, Exakta, Leica R, M42, Nikon F, Olympus OM, Pentax K, Topcon8
Canon EOS
Sigma SD
44Contax/Yashica, Exakta, Leica R, M42, Nikon F, Olympus OM, Pentax K, Rollei QBM, Topcon9

From the above table, it immediately becomes clear that Canon EOS and Sigma SD-series cameras are the best if you like experimenting with vintage manual focus lenses, and Nikon cameras are poorly suited for this, since popular mounts such as Contax/Yashica, M42 or Olympus OM cannot be adapted.

One more important note. Both Canon EOS and Sigma SD-series cameras have the shortest flange distance of any modern digital SLR camera, which is 44mm. Therefore, if the lens has a mount with a flange focal distance of less than 44mm, that lens cannot be adapted to any digital SLR camera.

Vintage SLR lens mounts that cannot be adapted to modern digital SLR cameras:

Lens mountFFD, mm Lens mountFFD, mm
Altix42.5 Fujica X43.5
Canon FD42 Konica AR40.5
Canon FL42 Konica F40.5
Canon R42 Minolta SR43.5

In the case of Canon FD, Konica AR and Minolta SR mounts, this is especially annoying, since these systems had many lenses with beautiful bokeh.

Some manufacturers may offer adapters for these mounts in variants with or without magnifying glass. With glass adapter, the image quality will suffer in terms of image sharpness, especially with fast lenses at large apertures (the most common adaptation and use case). With glassless adapter, you will loose the ability to focus at infinity. The choice is yours, however the only right way to adapt such lenses is to use a mirrorless camera.

Lenses designed for rangefinder cameras can only be adapted to rangefinder or mirrorless cameras:

Lens mountFFD, mm Lens mountFFD, mm
Contax RF34.85 Nikon S34.85
Leica screw mount28.8 Leica M27.8

Adaptation table

Lens mount ▿SLR ▹CanonSigmaSonyPentaxNikon
Agfa Ambi Silette bayonet mount • FFD=43.5mm
Altix breech-lock mount • FFD=42.5mm
Canon EF bayonet mount • FFD=44mm
Canon FD breech-lock mount • FFD=42mm
Canon FL breech-lock mount • FFD=42mm
Canon R breech-lock mount • FFD=42mm
Contarex bayonet mount • FFD=46mm
Contax/Yashica bayonet mount • FFD=45.5mm
Contax N bayonet mount • FFD=48mm
Deckel bayonet mount • FFD=45.7mm
Exakta bayonet mount • FFD=44.7mm
Fujica X bayonet mount • FFD=43.5mm
Icarex bayonet mount • FFD=48mm
Konica AR bayonet mount • FFD=40.5mm
Konica F bayonet mount • FFD=40.5mm
Leica R bayonet mount • FFD=47mm
M37 screw mount • FFD=45.5mm
M40 screw mount • FFD=43mm
M42 screw mount • FFD=45.5mm
Mamiya CS bayonet mount • FFD=45.54mm
Mamiya E bayonet mount • FFD=45.54mm
Mamiya ES bayonet mount • FFD=44.5mm
Minolta SR bayonet mount • FFD=43.5mm
Minolta/Sony A bayonet mount • FFD=44.5mm
Miranda dual mount • FFD=41.5mm
Nikon F bayonet mount • FFD=46.5mm
Olympus OM bayonet mount • FFD=46mm
Pentax K bayonet mount • FFD=45.5mm
Pentina bayonet mount • FFD=45.5mm
Petri breech-lock mount • FFD=43.5mm
Praktica B bayonet mount • FFD=44.41mm
Praktina breech-lock mount • FFD=50mm
Rectaflex bayonet mount • FFD=43.4mm
Rollei QBM bayonet mount • FFD=44.46mm
Topcon bayonet mount • FFD=44.7mm
Topcon UV bayonet mount • FFD=54mm
Yashica MA bayonet mount • FFD=45.8mm
Yashica Pentamatic bayonet mount • FFD=43mm
Adaptable Use w/o adapter Not adaptable

Lens modification

Lens adaptation should be distinguished from its modification, which is usually performed when the use of a lens with a camera via an adapter is impossible due to shorter flange focal distance of the lens. During this modification process, the technician removes the original lens mount, grinds off a portion of the rear of the lens barrel and installs a new mount. For example, in order to modify a lens with the Canon FD mount to use it on a camera with the Canon EF mount, you need to grind off 2mm, which is the difference between the flange focal distances of these mounts.

Thus, modification is a custom-made procedure for permanently changing the mechanical construction of a lens (including its mount). Unlike modification, adaptation always implies the use of an adapter while keeping the original lens mount.

Exposure metering and focusing

Before taking a picture in fully manual exposure mode (M), the shutter speed and ISO must be selected by the photographer, as well as the aperture, which is controlled using the diaphragm ring on the lens barrel. Focusing is also done manually. Shooting in shutter-priority (S/Tv) or programmed auto exposure (P) modes is not possible because the camera cannot automatically control the aperture. But in addition to the fully manual exposure mode (M), you can shoot in aperture-priority auto exposure mode (A/Av).

If the adapter does not have a focus confirmation chip, your camera may refuse to take pictures because it does not "see" the lens. This is not surprising: after all, the adapter is just a piece of metal, and the camera cannot exchange any information with it. Therefore, when using an adapter without a chip, do not forget to enable the so-called "shoot without lens" option in the camera menu.

A couple of good advices at the end

1. Do not adapt any zoom lenses or slow prime lenses (except for such special tools as fisheye, macro and shift lenses). There are many inexpensive autofocus zoom lenses available for your digital SLR camera that can replace them and can be used without an adapter.

2. If you own a Nikon digital SLR camera, do not waste your time buying lenses like old Soviet Helios-44 with M42 screw mount, or similar, as well as adapters with magnifying glass. A variety of high quality manual focus AI/AI-S Nikkor lenses have been produced for your system since 1977, many of them have beautiful bokeh and excellent sharpness, not to mention the high build quality. You should not adapt third party lenses to cameras that are not suitable at all for this.

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Pred Schilich
Pred Schilich
2 years ago

Excellent advice.

Colburn Ingle
Colburn Ingle
2 years ago

Excellant article. I have a Topcon AR-1 auto w/numerous lens and would like to use the lens on a digital camera body. If I’m reading the chart correctly this would be possible?

Danno
Danno
2 years ago

Do you have a link that would show how to adapt UV Topcor lenses to Fuji x mount mirrorless cameras? I am trying to figure out where the aperture blades live on this system, are they ik n the lens or the lens mount ring?

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