Thank you.  This is what I was thinking on the VC filters.  I know that
you can only get a good of a print as your negative, and that expanding
or contracting during developement will give you more leverage than
using VC filters...  but for someone who's just learning the basics of
the system - VC will work for now.

OK, as most of you know, I am not a true "Zonie" but I use some of the
techniques but without the rituals.

First:  the whole true film speed thing can be thrown out the window,
instead choose a "comfortable" EI instead, note that my film choice outside
is TX, TXP in the studio, I usually rate both at 200 and meter with a Gossen
Luna Pro F.  When I shoot flash in the studio I adjust my lighting to get a
contrast range that I know will reproduce on my normal paper.  When I shoot
available light I either use the Luna Pro in incident mode which is
essentially metering for N in Zone terminology, or since TX compresses
highlights nicely, I meter for adequate shadow detail and don't sweat the
highlight placement.  For the last 100-150 years that's been called "expose
for the shadows and process for the highlights".

Expansion and contraction are done with VC filters since you can't process
individual roll film frames, I understand that Ansel Adams used multiple
Hasselblad backs so that he could do expansion and contraction with rolls of
film.  I have heard of a guy using a 35mm Exacta (which had a film cutter
built in) and would adjust processing for each series of shots.

You could shoot a Zone series, something like this:

expose a gray card with a black X and a white X, meter for Zone 5, shoot a
frame, close down four stops, shoot a frame Zone 1 (5-4), open up one stop,
Zone 2 (5-3), etc.  when you're done process for the manufacturers
recommended time.

adjust the exposure of your contact sheet so that "Zone 5" looks the same as
medium gray, two negatives over would be "Zone 3" and "Zone 7", "Zone 3" the
gray card should be pretty black but you should still be able to see the
black X on the contact sheet.  On the contact frame for "Zone 7" negative
the gray card will be pretty light but you should still be able to see the
white X.  One refinement, check that you are printing for maximum black, the
film edges (which receive no exposure) should print to max paper black--if
you have to print lighter than this to get a medium gray from your "Zone 5"
negative you are not giving your film enough exposure.  If your "Zone 3" and
"Zone 7" negatives have no detail when printed you need to reduce your
development time if your "Zone 2" and "Zone 8" contact prints look like my
description of what 3 and 7 should look like you need to increase you
processing time.  I would not vary my processing time by more than +/- 15%
for a second test if needed.  It probably will be needed.

So you're down to one last thing:  metering, when I use a spot meter or my
Luna  (the F and SBC use a readily available 9v., not a PX-625, and have a
factory Zone scale), I will normally use one of the following:

1)place shadows with detail on Zone 3 and let other values fall where they
may

2)check my highlights and adjust exposure to keep highlights no higher than
Zone 8 (I can push them up the scale in the darkroom),

3)or use my incident metering mode for an average exposure and check the
placements as required depending on how much time I have.

BTW film densitometers are cheap, I picked up a little X-rite at an auction
for $5.00 (graphic arts but hey it measures density as well as DOT) and was
given a Sergeant Welch Densichron.

I use an old Kodak model 1 densitometer which cost me about $20 -
surely within the budget of any photographer.  As to the question of
economics,  using the zone system, which forces you to slow down on
your shutter snapping will cause you to use less film and to have more
good negatives.  The savings in film and processing costs will cover
the cost of the densitometer in no time at all.  

I shoot using the  Zone system in LF, and when shooting roll film,
although I do not do a 'real' zone system I do tend to figure what
development I will use for the roll, and expose accordingly.

I've been reading about the zone system and I'd like to start
experimenting with it... the only problem is I can't afford a
densitometer to do my calibrations.  Is there point in trying to use
the zone system without calibrating?  What about using a scanner as a
densitometer?  We are thinking about getting a microtek scanmaker i900
where I work - which boasts 48 bit / 4.2 max density.  So I would have
access to that, but I don't know much about the technicals of scanners
- if 4.2 is good enough or not.  I think it would work for negative
scans since there is no glass, but I'm not sure about scanning prints.

Also, I shoot purely roll film right now...  can I just substitute
development adjustments with contrast filters?  Or does it not work
that way?