I'm planning to get started on Black & White photography, but I'm getting a little confused about what is meant by contrast & density.

Is contrast the difference between the darkest and lightest areas of the scene being photographed? Or does it refer to the actual negative? How can you tell by looking at a negative whether it is high/low contrast, or whether it is "thick" or "thin" - (another term I've come across).

I've seen that some films are described as contrasty - what effect will these have?

I hope someone can explain these things (simply!) or recommend a good book (my eyes keep glazing over when I read Ansel Adams, "The Negative")...

-- David Nash (nashcom@btinternet.com), October 27, 1998

Answers

1.) Contrast refers to the slope of the negative's curve: how fast does the film in question go from it's thinnest ( just above being completely blank (blank=base+fog (this is always there)) to being so saturaturated (thick) that exposing the film any more will not change its density. 2. This curve (& slope) are established through reading the negative with a machine called a densitometer. one way to establish that curve is to first determine what the minimal amount of exposure is that is (my numbers could be wrong here, so please insert the correct ones) .xx above the base+fog density. In a basic Zone system terminology this is zone 1. (b+f=zone 0) and then exposing in steps of one exactly one f/stop(.30 units of density) ever greater levels of exposure. Your exposure should be of something completely blank and evenly illuminated. initially set your meter at the manufacturers recommended ISO. the contrastier the film, the steeper the slope. 2.) Contrast, to a certain extent, can be controlled in the developing process by choice of developer and time of development, 3.) Some subjects and some lighting conditions need more contrast and some need less. Generally speaking: the slower a film is the contrastier it is, and the flatter the light the more contrast is needed. 4.) Sources: "The Negative" and "The Print" by Ansel Adams (yes, i know, it is worse reading than Finnegan's Wake but eventually you get the hang of it); "Beyond the Zone System" by Phil Davis. I highly recommend the workshops offered by the Santa Fe Photo Workshops and also those offered by John Sexton.

-- Ellis (evphoto@insync.net), October 27, 1998.

David, Ellis sums it up well. There's really no easy way of mastering these concepts.

For a simplified review of Adams' rather pedantic book, you might read Fred Picker's "Zone VI Workshop". It's short, well written, and very straightforward. Kind of a Zone System Lite.

Picker will help you understand the inter-relationships of initial film exposure and subsequent film development, and allow you to produce the optimum negative density curves necessary for fine prints. Once this is understood, Adams' charts, endlessly graphing and plotting film density curves, will start to make sense.

Good luck, Sergio

-- sergio Ortega (s.ortega@worldnet.att.net), October 27, 1998.

I'll do my best to answer your questions without lapsing into Zonese.

"Is contrast the difference between the darkest and lightest areas of the scene being photographed? Or does it refer to the actual negative?" Yes on both counts. Contrast can describe the lighting in the original scene, and it can describe the negative. The current issue of Photo Techniques has an excellent article explaining the qualities of light (including contrast).

Density describes how much light the silver on the negative will block (or how dark the image on the negative looks when you hold it up to a light). "Thick" refers to a negative with higher density--it blocks more light; "thin" refers to a negative with lower density--it lets more light pass through.

A negative with high contrast will have some areas that are very dense (thick) as well as areas that have little density (thin).

Some films (usually slower speed films) will yield a negative with more contrast than other films (usually higher speed films) for an identical scene when both are exposed and developed as recommended. Of course, one great strength of b&w films is the ability to control the contrast of the negative by varying exposure and development.

There are plenty of books that do a good job of describing the basics of b&w photography. Your best bet is to visit a bookstore or library and look through what's available.

-- Mike Dixon (burmashave@compuserve.com), October 27, 1998.

I highly suggest (if you can) that you attend the Beyond the Zone System workshop taught by Phil Davis. I attended the workshop this past July down in Flagstaff, AZ. It was incredible! You learn by actually DOING, not just hearing about it. You test the film and paper you plan on using with a densitometer and learn about film and paper curves. Again, you will learn by DOING. If you decide to go to on of the workshops, read Phil's book "Beyond the Zone System." It helps, though, if you're like me, you'll have to read it several times before to understand (or at least try!) the material.

-- Ron Whitaker (contact@141.com), November 02, 1998.

I highly suggest (if you can) that you attend the Beyond the Zone System workshop taught by Phil Davis. I attended the workshop this past July down in Flagstaff, AZ. It was incredible! You learn by actually DOING, not just hearing about it. You test the film and paper you plan on using with a densitometer and learn about film and paper curves. Again, you will learn by DOING. If you decide to go to on of the workshops, read Phil's book "Beyond the Zone System." It helps, though, if you're like me, you'll have to read it several times before to understand (or at least try!) the material.

I needed to add that if you're interested in the BTZS workshop, go to www.darkroom-innovations.com and contact Fred. They're the photography-related company down in Phoenix that puts on the workshop.

-- Ron Whitaker (contact@141.com), November 02, 1998.