Sirius the dome out allows the sensor to "see" more of the light sources effecting the subject matter.
The sky, the reflection off the other walls of the of the canyon and the valley floor each contribute to the exposure in addition to the sun.
1. The limiting factor is the paper.
2. Most papers will hold about a 7 zone (or stop if you want to call it that) range of tones. The rest is black and white.
3. An incident meter will provide an exposure to render middle gray as middle gray only if you have previously tested your meter to provide a proper exposure called the speed point that is a certain amount about film base plus fog. (You need a rock to stand on).
On 1&2 could you provide a bit of context on what you are responding to.
On #3 the incident meter provides a scientifically objective reference point that we regularly refer to as middle gray from the scene. The testing for the film has already been done, its simply the ISO speed. If our tools are working correctly and we are reasonably capable in processing our films, then our results will be very close to ISO standard and mid tones will fall nicely on the paper with reasonable shadow and highlight detail.
There are several wild cards here. Our skills and understanding are the biggest factors. The other big one is creative choice.
Testing is valuable in refining our skills, understanding, and creative vision but the baseline is already there.
I read this when Mark first posted it, and it swished over my head leaving not a trace.
I revisited it a couple of weeks ago, when I understood most of it.
Accordingly, I've started clicking the dome across on my little Digisix where appropriate.
Result: many more beautifully exposed and easy-to-print negatives in the past fortnight.
This is a slightly long-winded way of saying thank you to Mark for the article.
(the zonology in the discussion still swishes past though :))
One thing which bothered me for very long time was, which grey is dome's grey? Though it is secret from the manufacturer but it has brought an insurmountable confusion in understanding a rather very simple concept.
Now, I am quite happy to meter(dome facing the camera) the shadow illuminance at box speed and developing it with a speed loosing developer.
Thank you pdeeh.
To a great extent this explains for me why so many people enjoy and get respectable results from center weighted camera meters.
The same can't be said of spot metering. The results can be significantly better than CW'd metering but spot metering is a true step into abstraction (visualization), subjective judgement, accuracy in aiming, and the world of film sensitometry and physics. If you don't "get" the concepts of zoning and how that carries through from scene, through film, onto paper (and I honestly believe that only a minority ever do) spot metering will be a frustration.
Incident metering for the first timer requires a small leap of faith, that a given amount of light will create a given reflection off our subject. The "problem" for incident metering is that it is "almost too easy". It is so good at getting a high quality camera setting with the dome pointed at the camera that most people never step past that and use it creatively.
BTZS concepts on metering may be interesting but I took it little more serious and for me that was one the biggest source of confusion.
Now, I ignore the most and concentrate on spicing the illumination of the concerned area with incident meter.