Flange focal distance – enlarger lenses

There are many different enlarger lenses available from the days of film photography. Many of these lenses perform very well for digital photography as well, once you are able to adapt them to work on your camera system. They do require a helicoid focuser for use, as they usually do not have a focusing mechanism on them. Most have M39 male threads for mount.

These different enlarger lenses of different focal lengths unfortunately have very different flange focal distances (FFD). The FFD is the distance from the mount of the lens (flange of the lens) to the sensor plane (point of focus on the camera). Each camera will have a mark on the top of the camera body to show where the sensor plane is (a circle with a line through it).

Lenses with shorter FFD may not be able to focus to infinity on certain camera systems i.e. it cannot focus in the distance as the lens is too far away from the sensor plane, and is only good for shooting macro. Those with longer FFD will require extension tubes in order to even reach focus at infinity.

I thought it would be a good resource if I documented the FFD for the enlarger lenses I own. As this will allow people to decide if the various enlarger lenses can be adapted for imaging with their system, and which thickness of helicoid focusers to use.

Enlarger lenses on test for FFD (Leica Focotar-II 50/4.5 is missing from the group photo)
Enlarger lenses on test for FFD (Leica Focotar-II 50/4.5 is missing from the group photo)

Method:

I mounted the lens onto my unmodified Sony A6000 via the Hawk Factory M42-NEX helicoid. I adjusted focus at maximum aperture for each lens on the furthest subject outside my window (trees far in the distance). Once focus is achieved & focus peaking pops up, I measured the distance from the front of the helicoid to the sensor plane marking on the top of the A6000 using a digital calliper.

Lenses tested:

1) Aico 35mm F3.5 old body enlarger lens (the different branded ones should work similarly)

2) Aico 35mm F3.5 new body enlarger lens

3) DOI 50mm F4.5

4) Paterson 50mm F3.5 3-element lens

5) El-Nikkor 40mm F4

6) El-Nikkor 80mm F5.6 (old version)

7) El-Nikkor 105mm F5.6 (old version)

8) Leica Focotar-2 50mm F4.5 (not pictured as I forgot about this lens until after taking the group photo)

Here are the results:

Screen Shot 2014-10-14 at 17.39.38As you can see, the FFD for many of these lenses are fairly similar, other than the longer focal length lenses. I do note that the FFD of the El-Nikkor lenses as described by Nikon are 1mm shorter than what I have measured – so do bear that in mind when considering this.

These lenses should not pose a problem for mirror less cameras to achieve infinity focus, as the sensor is not as far back as on DSLRs. But with DSLRs the 50mm focal length and shorter lenses are unlikely to be able to focus to infinity without mounting them closer to the sensor plane.

Boon