But remember it is the eye of the beholder that is the most important tool, combined with the human brains. In this command center the final area will be chosen and defined as middle-gray (Kodak test card).

If all fails, we can say: "We've found the problem ..It is us"

I could tell you stories...here is just one - On a Seminar I met this guy, doing B&W photography for more than 6 years, complaining about emulsions as he had most of the time very thin negatives, forcing him to use grade 4 most of the time. Questioning him about how he used the meter gave me a dumb look but it turned out he used incident light mode with his Minolta Autometer III. Nothing wrong with that if you know how... (Note: Working in incident mode requires correction of ISO - half the ISO value i.e use 50 ISO instead of 100 ISO to get the shadows a little more pronounced from filmbase plus fog - ) Well he was pointing the dome to the subject instead of the other way around i.e facing the camera!
It was very easy to point at the culprit instantaneously, hence his negs could be printed on grade 2 or 3 and came out nicely.
You have to understand what a meter really does....A reflected light exposure meter expects every scene will have a reflectance of 18% (Kodak Neutral test card).
If this is the case than your negatives will be okay, but...

Reflected Light

Incident Light

Above you will see three cards : White - Gray - Black
Exposures were made using reflected light metering. Result, all cards have the same density! Imagine what it will do next time you make an exposure. To get pure white open up two stops - To get pitch black close down two stops.

This is the most important lesson and proof in your career as a photographer. There are lots of shuttertime/aperture combinations possible, however there is only one that will yield the correct exposed negative.

Knowing all this now, how do we proceed? There are a few possibilities, the most simple one is carry a Kodak Neutral Testcard with you all the time, measure the card and let the rest of the tones fall into their place.

Second one is the old rule : Expose for the shadows and develop for the highlights
We will speak about exposure, the development part maybe later...
What is a shadow and what is a highlight? Good question. We concentrate on the shadows for now(Most important part in B&W Neg)...We have to decide if we want detail in the shadow or not! If we decide for the first option, we will measure zone III and see what the meter says (remember it makes 18% grey)however we know this zone is two stops denser than Zone V. In stead of reading the value on Zone V we will use the mark Zone III and expose accordingly resulting in the correct density in the negative.
Example:
Meter readout is 1/60 @ f16.0 we will correct this by using 1/250 @ f16.0 (Two stops difference from Zone V (thus getting less density in negative resulting in Zone III in Print.
If you decide to expose for Zone IV (Much detail) you should expose 1/125 @ f16.0 (One stop from middle grey)>

If we wanted no detail (why should we do this? - pure theoretical) we should expose for Zone II resulting in an exposure of 1/500 @ f16.0 (Three stops from Zone V)

Zones differ one stop from each other as can be seen below. If you measure an important part in your photograph, decide in which tone you want it and correct your exposure accordingly.
After you've chosen your lowlight Zone, point your meter and see where the important high Zone falls. If the difference is more than 5 stops (log 1.50) we need to make corrections in the development time also!

Well this is nice Huh? We are in control....Actually this is only a primer, if you want to go any further, surf the WWW and search for "Zone System"
We did only talk about the metering, but you can imagine when contrast is very low or very high we have to do something with the development also.

If you go all the way and get the hang of the Zone System, don't become a slave of the system.
Moderate use and understanding of the system will pay off....but remember:

A print full of tones but empty of emotional content is as dull as a perfectly typed but meaningless manuscript.

Take your time...(Some things in life can not be rushed and shouldn't be...a.o making a good Photograph)
Know what you want and what you are metering...

A very good book, we heartily recommend is: "The Negative" by Ansel Adams (ISBN 0-8212-1131-5)

One of my favorites is "Schwarzweiss-fotografie nach dem Zonensystem" Author Andreas Weidner. Verlag Photographie ISBN 3-7231-0041-4
Leider nur in Deutsch....and difficult to get!
If the language is no problem for you, in my view the best book on the system!

NOTE: OoP might be available used at Amazon.Com

The second meter is the Minolta auto spot II, Ideal is a 1° Spometer as shown here.
Caution though, one needs to know what part to measure, understanding the zones and lots of experience with these meters!

A spotmeter and viewing filter are the mandatory tools to measure areas as shown.

Just to name some brands; Minolta, Pentax, Soligor, Sekonic Spot, Gossen Spot.
Several meters with a 5° or 10° accessory are suitable also. Note: Ansel Adams used a Weston Ranger 9 with a 18° angle for most of his landscape scenes.

Both meters pop-up regularly on Ebay at a fraction of the cost....

The Viewing filter is a great help to determine zones and contrast as well.
Nowadays available through TIFFEN and SPECTRA.

Besides determining lighting contrast, the Panchromatic Viewing Filter also shows the effective tonal separation within the scene. Colors that seem to blend together when viewed through the Filter will, likewise, show no separation when photographed. If tonal separation is desired a suitable corrective filter should be used on the camera lens.

In practice you hold the filter for your eye while looking and studying the zones and contrast.
As the eye adapts very quickly, move the filter in front and away from the eye at short intervals.

NOTE:: The reason I've chosen the Weston Master is a personal one.. (I feel a meter from the same era would be more appropriate).
Actually the Weston Master available in 1955 was the Weston Master III. It did read Cd/ft² directly.
A very good choice might be the weston Master IV, the very last meter reading Cd/ft²
It speaks for itself you can use any meter you fancy, more important however is you know how to operate and interpret correctly! If you don't want to do mental conversions for bellows draw and filter factors there is the film plane meter.
Generally speaking there are 4 modes of light measuring, each mode has its own advantages and drawbacks.

Zone III example:
When detailed shadows are called for, we do a close reading of this object only and align the dial with the black dot against the found number(13)

Clear north sky (panchromatic rendering). Dark skin. Gray stone. Average weathered wood. Middle gray (18% reflectance)

Zone VII example:
Checking highlight: if we want still some detail here, we make a close reading of this object only and align the dial with the red dot against the found needle value. Please note this is only done to see where the highlights fall...If the difference is more or less than 4 stops with the ZONE III value we have to compensate with development time.

Generally speaking we can say:
#1 If the subject is unusually light, decrease the calculated exposure by 1/2 to 1 stop.
#2 If the subject is unusually dark, increase the calculated exposure by 1/2 to 1 stop.

When using Black & White film it is advisable to adapt your Iso setting 1/2 to 1 stop lower, to raise the dark zones a little more above filmbase and fog.
Note: also when working with the incident light meter, our eyes and perception remain very important.

Don't get obsessed with the weight of a camera. If you are going to take pictures in the field, you'll be carrying a large tripod, film holders, lenses, a dark cloth, a light meter, and all the chowder that goes with taking pictures. Plus chances are you'll also be toting another smaller format camera. So all that will probably weight in the neighborhood of 20 pounds, and probably even more. So what's the difference between 22 pounds and 25 pounds? Not much.

* Slow down, take your time, and work methodically. There are more ways to screw up than you can imagine. The quickest way to mess up is to try to save time and work quickly. There are times when you have to work fast, like when the light is changing, But in general, large format photography is slow and deliberate. If you come up with a system and stick with it, you'll ruin a lot less film.