In article <332716A7.95A@us.oracle.com>, acohen@us.oracle.com says...

>I've never seen bellows used on a 35mm camera, but I have seen extension
>tubes. Can anyone comment on differences/advantages/disadvantages
>between the 2?

Bellows used to be popular accessories, until people realized that
the minimum extension is too long for many uses, the longest extension
is WAY to long for almost any use, and tubes are more compact, less
delicate, and can easily maintain the auto-diaphragm feature (all making
their use much easier than bellows).

>When I typically think of bellows, I think of a 4x5 or 8x10 camera,
>where you need 2 tripod mounts: one for the lens and one for the back.
>Is the same true ofa 35mm bellows?

Hmmm, never heard of that... No, only one tripod socket is on the
bellows.

>If it makes a difference, a would use them on a Canon FD mount.

You should be able to find used bellows for it - but I have a nice
set of two Canon tubes for the FD mount for sale.... (e-mail, if
interested - I will sell them for $40 post-paid).
Hope This Helps