what size of lens would i need to photograph macro (flower bud) size subjects
with a 4x5 field camera, where the bellows do not extend more than 15
inches?

Hello, you have an interesting problem that boils down to a couple of
factors, which I have addressed below. Please let me know if you have
any questions before rating this answer...I want you to be satisfied.

The short answer is that you can use an 80mm or shorter lens on a
camera with 15 inches or less of bellows draw. But the complication is
finding a lens that short that is of good macro capability. I explain
both parts of the problem below as best I can, and if you need
clarification, please let me know, because I enjoy this field and am a
large format photographer myself.

First of all, let's just presume you have a flower bud about an inch
across like a rosebud), and you want it to nearly but not quite fill
the space of a negative (which is about 3 7/8 by 4 7/8 inches when you
subtract the margins). In other words, the one inch bud will be about
3 1/2 inches on the negative or transparency.

That means a magnification of about 3.5X. Using the standard table of
lenses for macro photography in the Kodak Professional Guide (full
citation below) on page 33, a fifteen inch extension will give the
magnification we are talking about with a 3 1/4 to 3 1/2 inch lens
(which is about an 80mm). This is the outside limit, meaning that if
you use any lens shorter than 80mm, you can get this magnification
with less than 15 inches of extension on the camera. To give one more
example, if you were to use a 50mm lens, you could get a 3.5X
magnification with about 9 inches of extension.

As you can see, using a shorter macro lens will give greater
magnification with a corresponding extension of the bellows on the
camera. However, finding a macro lens for 4x5 large format use in
these short focal lengths is not easy. The Nikon, Rodenstock, and
Schneider Macro series lenses, according to the B&H Professional 
Photo Source Book, provide only a 120mm at the shortest. You can check
the B&H web site, probably the most comprehensive professional supply
company in the country, to confirm this at:

http://www.bhphotovideo.com/bh2.sph/FrameWork.class?FNC=CatalogActivator__Acatalog_html___CatID=24___SID=F3BF8B73480

So this begs a second question: is there an 80mm or 50mm lens that
will work as a macro for large format photography? You don’t ask that
specifically but I imagine you will be wondering just that by now, so
here goes!

The answer takes us into less conventional territory, but I have
myself adapted a 50mm f/3.5 Zuiko (Olympus) macro to a 4x5 camera and
gotten acceptable results, with the camera bellows extended to the
range we have been discussing. This is a well corrected lens in the
center, but it probably does not match the standards of a true large
format macro in terms of contrast and sharpness. It may no longer be
truly flat field, either, but unless you are doing copy work, this
should not be an issue. According to View Camera Technique By Leslie
Stroebel (I have the 1967 edition cited below), macro lenses for what
he calls “miniature” cameras, meaning 35mm cameras, are excellent, but
present the problem of not having built in shutters.

Large format lenses typically have shutters, of course, and I would
assume, from experience, an acceptable result would be possible with a
high quality large format lens even though not designed specifically
for closeup work. These should maintain good if not surpassing results
at great bellows extensions. One commonly sharp example of a short (70
to 80mm) lens for normal (non-macro) use is the newly introduced
Schneider Super Symmar 80mm f/4.5. At the shorter end, the Rodenstock
APO Grandagon 55mm f/4.5 is unusually sharp, and would probably hold
up better than most in macro settings. Resolution characteristics of
both of these lenses is available from this independent test site (but
remember, they are testing at infinity):

http://www.hevanet.com/cperez/testing.html

Finally, between these two extremes, you might find an 80mm Zeiss
Planar or 80mm Schneider Xenotar (both are available used on ebay at
times in separate lenses with their own shutters, or new as
accessories for Rollei and Hasselblad medium format camera systems).
Like the Olympus example above, these would not cover 4x5 at infinity,
but when doing macro work they would easily cover the whole negative,
and with very good results. This might be the best overall choice if
starting from scratch.

One last note: to increase sharpness using lenses not meant for macro
work, you can try mounting them backwards on the lens board...this
makes them both sharper and harder to use! Something to play with.

I hope this is helpful. You may need further clarification, and if so,
don’t hesitate to ask! There remain issues of lens mounts, lighting
the subject when so close to the camera, depth of field, and so on,
but your basic concern about magnification and bellows draw is a
simple math problem and is covered above.

Sources:

View Camera Technique, by Leslie Stroebel. Hastings Houise,
Publishers, New York, (1967)--(second edition, 1972).

The Professional Photo Source Book, by B&H, self published in New
York, (1998) This is really an elaborate product catalog, very
helpful.

Kodak Professional Photoguide, by Professional and Finishing Markets
Division. Eastman Kodak Company (1977)


Search strategy:

I relied on my own experience and personal library, then searched the
bookmarks on my computer.

--lmnop-ga

the comments were well thought out and beautifully commnicated.