Surface for Zone System test?

[lbi115l]

I was wondering what is the recommended surface for a test of the

zone system. I know what St. Ansel recommends in his book. I'm

testing TMX 100 and have white and black cards (large) as well as

some other surfaces. The test must be outside.

 

Thanks.

[ed_skibeki]

Unless you have access to a densitometer avoid smooth textureless surfaces. You'll need some texture to detect that first evidence of shadow detail ie. zones 2-3 and the last visible highlight detail, ie. zones 7-8. Terrycloth towel, for instance, is a good material, and stay away from very dark colours.

[howard b. schwartz]

18% gray card. follow the procedure on pages 239-244 in adams' book the negative.

[richard_cochran]

The beauty is that it doesn't much matter. Black card,

white card, dark grey, light grey, whatever. It's probably best to

avoid things that are very strongly colored, because the

spectral sensitivity of your meter may not match that of your

film, throwing an unwanted variable into the situation.

Use something that can be evenly lit, with which you

can completely fill your meter's field of view. A small

bit of surface texture can be helpful in distinguishing

"black" from "black with detail" and "white" from "white with

detail".

<p>

For practical reasons, mid grey can be nice, because you can

stick a small note in the corner, with exposure data

written in dark black

marker on bright white paper, and it'll still be legible on virtually

all the exposures. But if you can handle the bookkeeping issues,

the testing should be the same on a black card or white card.

I recommend you try at least partial testing with both colors

and see.

[lbi115l]

Thanks for the answers. I have a grey towel that I'll use.

 

A grey card won't do it, I am testing a 40mm lens for my Bronica ETRS, the card I have is WAY too small. The bookkeeping issue is not problem for me, i routinely record details for every exposure anyway.

 

I have one other question. My lens is only adjustable in whole-stops. Is it even worth doing then?

[nacio_jan_brown3]

Actually, you don't need texture to tell whether there is any density change. Comparison of the image area with the clear film base between frames will show density differences. But, beware: the presence of density discernible on a light box doesn't tell the whole story. For your lowest non-black zone, the density must show up as (just) distinguishible from black on a *print.* Getting back to the test target, using a smooth mat board is ok. Also, if you want to be rigorous, keep your lens focused at infinity, as the effective f/stop changes as you focus closer. This means that you can use a small test target, like a gray card, as long as you fill the frame with it (and don't cast a shadow on it in the process). njb

[donald_miller1]

When you indicated that the gray card was way too small, it is not important that the lens be focused on the metered object. In fact the lens should be focused at infinity and then the camera can be brought to the point where the metered object fills the frame. This is the correct way to test, since to focus closer may bring bellows extension factors for close focusing into play. If these are not accounted for the test will not be valid.

[lbi115l]

Nacio hit the nail on the head with the casting a shadow. There's no way I could do it with this camera setup w/o a shadow. I just bought an 8x10 view camera, to be delivered next week, and it will be a while before I have the film holders and lens for it. I have decided to wait to test film until I get that camera. I intend to use it for all of my serious Zone System work (anything but quick shots for school) and will test that.

 

Thanks for all the advice.

[britt_park]

Nothing quite as good as an evenly lit stucco wall.

[andrew_hull]

Terry cloth towel.

[joe_lipka3]

How about testing what you usually photograph? Towels, grey cards and the like can be test subjects, but wouldn't a more valuable test be what you might typically photograph? Wouldn't it make more sense to learn what exposure and development would be for tree bark in the deep shade would be rather than a towel? Something to consider.

[bong]

You can also use a piece of milk plexi to cover the lens and shoot your tests. The milk plexi provides a good textureless result that works well if you have a densitometer. See <a href="http://www.cicada.com/pub/photo/zs/">www.cicada.com/pub/photo/zs</a> for details.

[johndc]

focusing at infinity is a good idea because the lens is not extended at all. furthermore, most lenses have their f-stops rated from the infinity position, so you're exposures will be the most accurate.

 

as for having only whole f-stops on your lens -- don't worry about it. i was worried about that too when i did my first test, but i soon learned it's no big deal. for the film speed test all that really matters is that the exposure for ASA25 is admitting more light than the one for ASA32, which is admitting more light than ASA40 and so on. you can approximate your 1/3-stop locations. if you really want to be a perfectionist, you can meter the lens first and mark off 1/3rds-of-stops with a pencil on the lens barrel, but this method has its own inconsistancies as well.

[tim_curry]

I used my spot meter and a gray card to test for film speed / zone placement. The "subject" was a north-facing white stucco wall splitting the field by a black poster board. I reasoned that my meter/card was the constant and the film speed the variable.

 

Run a series of exposures with varying film speeds and make notes about the dark and light when processing is done and proofs are made. Will get you pretty close in one roll of film.