Just curious as to how much draw is needed for a tabletop shot with a 210mm lens. Or how about 90mm, or 135mm for Macro work? I have 18" on my current camera - but the bellows is not interchangeable, and was wondering if that is sufficient or whether I would need more for a 1:1. I've tried a still-life shot of fruit in a plate, but couldn't get the image that I wanted - final image was too small.

-- Tony Pulsone (pulsone@media.mit.edu), February 06, 2001

Answers

If the image is life size, you need 2 focal lengths of bellows. At half life size, you need 1.4 focal lengths of bellows. At infinity, you need one focal length of bellows. You can interpolate everything in between.

-- Ken Burns (kenburns@twave.net), February 06, 2001.

Another thing to take into consideration in addition to the amount of bellows draw required is the lens-to-subject distance. When the image is life size and the bellows is extended 2 focal lengths, the lens-to-subject distance will also be 2 focal lengths.

With your 210, the bellows will be extended approximately 420mm (about 16 1/2 inches), and the lens-to-subject distance will be about the same. If your lens-to-subject distance must be greater than that for some reason, you will need a longer focal length lens. However, because of the 18" limit on bellows extension, longer focal length lenses will probably prove to be a limitation instead of a solution.

With shorter focal lengths, you will be able to obtain life size images with both less bellows extension and less lens-to-subject distance. As a matter of fact, you will be able to get images greater than life size with a 135 or a 90. I'm not sure what magnification is acheivable with the shorter lenses, maybe someone else can help.

However, if life size is what you want, you can obtain it easily with you 210 using the bellows extension available.

-- Ken Burns (kenburns@twave.net), February 06, 2001.

If you're short of bellows, you can also go to a shorter focal length than you might normally use with the format, since a lens that doesn't cover at infinity might likely cover at 1:1 or greater. You might try, for instance, a reverse-mounted 80mm or 50mm enlarging lens for enlargements beyond 1:1.

-- David Goldfarb (dgoldfarb@barnard.edu), February 06, 2001.

David brought up a good point. If you do any darkroom work, you probably have a 135 or 150 enlarging lens used for 4x5 and shorter ones if you also work in smaller formats. You could easily use your 4x5 enlarging lens for life-size images and obtain very sharp results. For images larger than life size, the results from a reversed enlarging lens will probably be far better than you will get with a Super Angulon or Grandagon since they just aren't made for than kind of application.

The reversed enlarging lenses can be attached in reverse to lensboards fairly easily using filter step-up rings attached to the lensboard by screws. Attach the largest diameter one needed to the board, then use other step-up rings to adapt the other lenses to the board.

-- Ken Burns (kenburns@twave.net), February 06, 2001.