Macro working distance

[Sizam]

Hi All,
I'm looking at picking up one of the Schneider macro lenses (80,120,180) but was wondering what the working distance from the subject will be for each lens at 1:1 for 4x5, how can I figure this out?

Thanks,
Sam

[Ole Tjugen]

Dead easy: Working distance at 1:1 is 2x focal length.

[Sizam]

Great, and is that from the film plane or the lens plane? I assume the film plane.

[BradS]

At 1:1, the film plane will be 2x focal length from the lens plane and the lens plane will be 2x focal length from the subject.

[Sizam]

Awesome, thanks guys.

Sam

[Leonard Evens]

It should be added that the lens plane's location must be determined to use this information precisely. For most lenses, which are pretty much symmetric in design, the lens plane is very close to the front of the lensboard. For some lenses, such as telephoto lenses it can be some distance from the front of the lensboard. You can always determine its position precisely if you have lens data for the lens. In particularly, it can be calculated if you know the so-called rear flange focal length.

You probably don't have to know this information that precisely, so I won't go further into how to do the calculation, but if you need to know it for some reason, let us know.