On 27 Mar 2003 03:07:22 -0800, vtb666@yahoo.com (Vinnie) wrote:

>Sorry for the OT post, but I had a question that's been nagging me for

>some time.

>

>The way I measure the tonal range of a scene is point my meter at the

>brightest part, and the darkest part and take the difference in stops.

> So if the shadow gives me 5.6/60 and the highlights give me 5.6/1000,

>that is 4 stops difference.

>Since most slide film has a 5 stop range, this shot will will be fine.

>

>I was reading one of John Shaw's books, and the way he does it is

>different. He compares the meter reading adjusted for tonality. So

>if the highlight and shadow in the above example were snow (say, 2

>stops brighter than 18% grey) and a dark rock (say, 1 stop darker than

>18% grey), he'd dial in +2 for the highlight (giving 5.6/250) and -1

>stop for the rock (giving 5.6/125) -- resulting in a 1 stop

>difference.

>

>What gives? Shaw's book implies that the latter method is to be used

>in determining if the tonal range of a scene fits within the range of

>the film.

>But as per my understanding, the latter approach doesnt answer that

>question (it does is tell me that if I expose for the snow, the rock

>will be 1 stop underexposed and if I expose for the rock, the snow

>will be 1 stop overexposed - but that wasnt the question).

>

>Am I missing something here?

Nope.

Different people have different ways of "thinking" the

exposure. For me, if the snow predominated, I would open

up 1 2/3rds stops from the snow-only reading and let

the rest do what it will (unless large shadow areas

were important enough to allow the snow to "blow out"

to white). BTW, most scenes have a FAR, FAR wider range

than 5 stops (though the results when shot with a 5-stop

range film can look good if shot carefully...) - if you

measure the brightest tone in sun-lit clouds,

water-reflections, the sun, etc., and compare this with

the darkest tone in a shadow area (wet black bark under

a bush, building interiors visible in the image area shot

outdoors, etc.), the range can easily exceed 20 stops.

I used to shoot Tri-X rated at 25 (to get the low shadow

info) and processed in POTA (to keep the high highlight

info), with interesting results. Though the negatives

were often so "flat" that it was hard to see what was on

them, prints on no.2 grade paper, while lacking

"brilliance", had a beautiful softness and smoothness,

with EVERYTHING in front of the camera in the print,

without manipulation - dark, wet bark on trees, with

sun and clouds in the sky; textured bright sun

reflections on street paving, with building interiors

easily seen through windows; etc. - with a sense of

all tones of the subject area having been recorded...

(I may put some of these images on my web page in the

"Aht" section one of these days - the show resulting

from them travelled to about two dozen museums in

the early '70's...)