With 35mm and roll film cameras, with few exceptions, the cameras have unique mounts, and lenses are not interchangeable between different camera makers. In the large format world, this isn’t the case. Camera makers don’t make lenses, and, unless physical size prevents it, any large format lens can be fitted to any large format camera. That isn’t to say that it would be satisfactory though.
With smaller formats, lens information may be interesting – how many elements, how many groups, size, weight etc. – but isn’t essential for use. Large format is a different kettle of fish. Lenses are designed to project an image circle. With 35mm and medium format cameras, the lenses are designed around a fixed format size. Large format on the other hand can run from 5″x4″ (or smaller – quarter plate at 3.5″ x 4.5″ is smaller and was used until comparatively recently, as our local paper has a negative archive of quarter plate plates) right up to 20″x24″. Whether a given lens will cover the format you use should be given in the data sheets.
Every lens performs best on the lens axis, with quality dropping away from the axis. And every lens, simply due to physical constraints, will project a circle of finite size. Coverage is complicated by the difference, particularly in older lenses, between the circle of acceptable sharpness, and the circle of illumination. With landscapes, it may not matter if the sky in the corner isn’t sharp, but with architecture it does matter. And some manufacturers may be more cautious about what “acceptable sharpness” is. One older lens design actually has different image circles specified depending on whether you consult the data of the German maker or the American importer.
Having more coverage than the bare minimum allows more in the way of camera movements, which are a large part of what makes large format cameras such flexible tools. Some lens designs allow coverage to increase as the lens is stopped down, so this should be kept in mind. Older lenses often have a larger circle of illumination and leave it to the photographer not to use the area outside the circle of coverage. As the image circle increases in size, so in general do the lenses – as you’d expect. Lenses are made to give a specific image circle, and this in turn means that as the size of the negative to be used increases, so lens choice decreases. Most lenses were designed to cover a 5×4 format and the vast majority will cover 5×7. Going up to 10×8, lens choice decreases, and by the time we arrive at the ultra large format sizes (typically 11×14, 8×20, 20×16 and 20×24) lenses are few. What they lack in number they make up for in size and weight…
So, it’s no longer a case of if you have a Canon camera, you buy a Canon lens. It’s more like the digital world of being able to fit an APS-C designed lens to a full frame camera but as a result not recording an image over the whole frame. The important piece of information is the image circle of the lens. Usually, the makers specify the circle as that obtained when using an aperture of f/22 and focused on infinity. Older designs will often increase the image circle as you stop down; lenses may have a quoted image circle too small to use on a 10×8 camera, but be usable on one if stopped down further. Also, the image circle increases as you focus closer, so again you might get away with a too small image circle if you focus closer than infinity. You can also apply a small amount of back tilt (explained when we look at camera movements) to add a little extra coverage.
Large format lenses are virtually confined to the second hand market now; and manufacturers have either dropped out completely or have begun to remove data on old products from their web sites. Schneider immediately springs to mind, as until recently they carried information on their old lenses on their web site. It’s now gone.
Some lenses are convertible – by unscrewing and using sections they can provide two or even three different focal lengths.
A lens needs to be mounted to a lens board to be attached to a large format camera; different cameras require different lens board sizes although Linhof/Wista and Sinar boards are the most common. To mount a lens, it needs to be unscrewed into two sections and a retaining ring between the two halves removed.; the front section is placed in front of the lens board and the retaining ring screwed back into place. The rear section is then re-screwed. To ensure that the retaining ring is tight, a lens spanner is used.
A lens may be sold with or without a shutter – the shutters are between lens types that screw between the lens elements. Lenses come in different sizes, and so do shutters. With many old lenses on the market, there are many different shutters and sizes; the common factor is the smaller the number, the smaller the size. The smallest shutters I have are Copal 0; the largest Ilex 5.
Now on to the annotated links.
Information on shutter sizes and measurements: https://www.sizes.com/tools/shutter_photo.htm