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Article about photographic lenses and equipment

Flange Focal Distance of Photographic Lenses and Cameras

At times there can arise a need to use lenses from one system with another. The most prominent example is the use of old lenses with modern SLR or mirrorless (Evil) cameras. This combination will work only under the following condition: the flange distance of the lens must match the flange distance of the camera.

So we decided to try out some old manual lenses in action. Usually you can attach these lenses using adapters. But not all of old lenses can be easily installed to any modern camera. The primary reason for this is one of the key parameters of a lens, the flange focal distance (FFD).

The flange focal distance of a lens (or camera) is the distance between the lens mount and the focal plane (the plane of the film or camera sensor).

Flange focal distance of photographic lenses and cameras

Flange focal distance is measured in millimeters. As such, taking for example the popular Canon EF, its flange focal distance is 44mm.

What is this important for us? It's simple. If the lens FFD is longer than the camera FFD (at least 1 mm, the minimum thickness of an adapter), it can generally be used with the given camera through an adapter without any restrictions, meaning that it will be able to focus to infinity.

If the flange focal distance of a lens is shorter than the camera’s FFD, then you'll need a substantial modification of the lens shank, or you must use an adapter with a compensating lens, which immediately negatively affects image quality. You can, of course, just use such a lens for short distance and in close-up work only though.

There is a structural problem in some SLR cameras (especially the Canon 5d and Canon 5d mark II). The lens may be suitable for the camera by FFD, but due to the camera’s design, the mirror will come in contact with the shank of the lens (usually this problem can be solved by either filing a few millimeters off the shank or disassembling the shank).

Here is a table of flange focal distances for modern and older systems. They are sorted by FFD value.

 

Table 1. Flange focal distance of modern photographic lenses and cameras

System (mount)

Flange focal distance (mm)

Note

Sony E (NEX)

18

Mirrorless (Evil) camera

Micro 4/3 (Micro Four Thirds)

20

Mirrorless (Evil) camera

Samsung NX

25.5

Mirrorless (Evil) camera

4/3 (Four Thirds)

38.67

SLR camera

Sigma SA

44

SLR APS-C camera

Canon EF(-S)

44

SLR 35mm and APS-C camera

Sony A / Minolta A

44.5

SLR 35mm and APS-C camera

Pentax K (KA, KAF)

45.5

SLR 35mm and APS-C camera

Nikon F (FX, DX)

46.5

SLR 35mm and APS-C camera

 

Table 2. Flange focal distance of older photographic lenses and cameras

System (mount)

Flange focal distance (mm)

Note

С-mount

17.526

Movie camera 16mm

Leica M

27.8

Rangefinder 35mm camera

Leica m39 screw mount

28.8

Rangefinder 35mm camera

Contax G

29

Rangefinder 35mm camera

Nikon S-Mount

34.85

Rangefinder 35mm camera

Konica F (A/R)

40.5

SLR 35mm camera

Canon R (FL, FD, FDn)

42

SLR 35mm camera

Fujica-X

43.5

SLR 35mm camera

Minolta SR/MC/MD

43.5

SLR 35mm camera

Praktica B

44.4

SLR 35mm camera

Exakta, Topcon

44.7

SLR 35mm camera

m39

45.2

SLR 35mm camera

m42

45.5

SLR 35mm camera

C/Y (Contax/Yashika)

45.5

SLR 35mm camera

Olympus OM

46

SLR 35mm camera

Leica R

47

SLR 35mm camera

Contax-N

48

SLR 35mm camera

Tamron (T2, T-mount, T-thread)

55

SLR 35mm camera

Pentax 645

70.87

Medium format camera

Pentacon Six

74.1

Medium format camera

Hasselblad

74.9

Medium format camera

Kiev-88, Salut

82.1

Medium format camera

 

Here’s what we can take away from the above data:

 
- Among modern 35mm SLR systems, the Canon EF (-S) mount has the smallest flange focal distance. This means that almost any lens of any old 35mm or medium format systems can be attached to this mount without any problems. Exceptions: lenses for 35mm Rangefinder cameras and (ironically) old lenses made by Canon (Canon R, FL, FD, FDn mounts).
 
- All old lenses, including lenses for 35mm Rangefinder cameras, can be attached with an adapter to modern mirrorless (EVIL) cameras due to their short flange focal distances.
 
- Nikon SLR cameras have a long flange focal distance. Therefore, it proves difficult to attach older lenses to this mount. But many great older lenses already have a Nikon F-mount and can be attached directly to a Nikon camera or have a removable shank that can be changed to the Nikon F-mount.
 
- Lenses for medium format cameras have a long flange focal distance and therefore can be attached to any modern SLR or mirrorless camera. But such adapters are not wide spread and somewhat expensive. Such an adapter may have a size comparable with the size of a whole lens and sometimes even bigger.
 
- Many different movie lenses for C-mount systems can be used with mirrorless (Evil) cameras (e.g. Sony Nex, micro 4/3 cameras, etc.)
 
Good luck in your experiments!

 

Useful links:

The most complete table of Flange focal distances on different systems

 

(с) 2010 Sergei Borodin

Author: Sergei Borodin 07.12.2010 10:05:20
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