Focusing Scales for LF Lenses

[ic-racer]

Actually the Horseman FA 4x5 camera works that way. It has multiple infinity stops and focusing scales for six different focal lengths.

[David A. Goldfarb]

Linhof and Leica focusing cams are ground individually for the lens (and older Linhof cams are also customized for one camera body), because the focal length of any particular lens of even the same brand and model depends on the refractive indices of the glasses used, so there are slight sample to sample variations. As long as everything is calibrated, you should be able to focus more accurately at wide apertures with this kind of system than with a camera that uses the same cam for all lenses of a certain nominal focal length.

Scale focusing is generally less precise than rangefinder focusing unless you can actually measure the distance with a tape measure, so scales tend to be generic for the focal length. Linhof doesn't customize focusing scales for each lens. On movie sets they do measure with a tape measure and cine lenses are often marked in finer increments than still camera lenses, and follow focus units are designed to be marked with a china marker for the shot, so scale focusing can be made more precise than rangefinder focusing.

A useful trick with a rangefinder press camera that can be calibrated to only one lens, like a camera with a Kalart rangefinder, is to mark infinity stops and scales on the camera bed for each lens that is to be used with that camera. Then if the rangefinder is calibrated, say, for a 135mm lens, you can use the rangefinder normally with that lens, but if you want to rangefinder focus with a 210mm lens, you would focus with the rangefinder, read the distance from the 135mm scale, refocus so the index mark points to the same distance on the 210mm scale, and you should be in focus.

[Steve Smith]

A bit more information then:

At the weekend I went to see an exhibition of marine photography by Beken of Cowes they also had on display the first two home made cameras which they used. The first seen here: http://www.cowes.co.uk/zonexml/story...=8776;cp=0-731 used 6x8 glass plates and was a twin lens design. Not a reflex though, just a ground glass to view with. The lens is mounted in a sliding box arrangement and apparently had just three focusing positions marked dinghies, yachts and liners.

The next camera was 5x4 and had a large viewfinder - just a look through type with a centralised cross for lining up.

Both of these cameras were made of mahogany painted black and were designed to put up with the harsh conditions encountered at sea. They are very simple and sturdily built and between them are responsible for some of the finest marine photography ever made (do a Google images search for Beken and you will see what I mean). Towards the end of the 1970s they started to use Hasselblads and later - that other technology!

Anyway, I was thinking about building something similar, possibly not so weatherproof but along the same lines.


Steve.

[David A. Goldfarb]

The lens is mounted in a sliding box arrangement and apparently had just three focusing positions marked dinghies, yachts and liners.

Now that's a distance scale that more cameras ought to have.

For those kinds of shots, outdoors, generally at least 15 feet from the subject, zone focusing is good enough. If you want to shoot with the lens wide open and/or at close distances, then you need more precision.

[Steve Smith]

It's the marine version of the close up portrait, groups of people and mountain icons seen on some simple cameras.


Steve.

[ic-racer]

Here are a few distance scales for focusing with various focal lengths.
Also, the Horseman FA, in case people don't know that that is.