Originally Posted by Helen B
"now, we can go back to the regularly scheduled program"
I always used my incident meter in night photograhpy. I walked into the deepter shadow areas and used it to meter the light falling in that area. I always got veyr accurate measurements as compared to my Pentax 1 degree digitan (Sone VI modified) meter. You can see some hight photos in my private ind critigue gallery. You'll note that the shadows have a lot of detail in them, directly attributable to the use of the incident meter in my opinion.
Try this site Mike: http://www.iespell.com/index.htm
Originally Posted by mikewhi
Let me see if I have seized this correctly. The whole point of incident metering is that it will always give you consistent results because the results are always based on a single variable: the primary light source. Therefore, as a general rule, what I need to do is take incident readings with the meter pointed toward the primary light source. Should I have more than one source, I suppose that I ought to use an average f-stop based on the square root of the two primary sources, no?
Have I got a handle on this?
Not exactly. A single incident reading with the dome pointed toward the camera will place Zone V in a good spot on the curve usually, but it doesn't help you with the contrast range. That's why it's a good method under studio conditions where you can point the meter at each light source to determine that the contrast range is within acceptible limits, and then take an exposure reading by pointing the dome at the lens from the subject position, measuring the effect of all the lights falling on the subject (except for backlighting) without need for any calculations.
To determine the contrast range of a scene where you can't control the lighting, as in a landscape, you can use spot readings as described in Adams's _The Negative_ or the incident method described in BTZS.
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Back to basics ... The value of incident metering lies in the fact that the intensity of light falling on the subject is the determining factor alone, and it is independent of the reflection properties of the subject. In use, an incident "dome" (purpose: diffusion) is directed - generally - toward the camera from the position of the subject.
Originally Posted by Max Power
Reflective metering *IS* dependent on the reflective characteristics of the subject or whatever is included in the area of coverage.
In "incident" metering the light alone is measured: a snowball will, in the final result be white; a lump of coal will be black.
In reflective metering, there is an assumption that whatever is included will be "average gray", reflecting ~18% of the light that falls upon it: A snowball, if it occupies the entire area of coverage will appear to be average gray; a lump of coal occupying the entire area will also, in the final result, appear to be the same "average" gray.
Incident metering is more accurate, BUT... It requires a separation of the metering from the camera position... one would have to travel all over a landscape, averaging many readings, to obtain an accurate result. Usually in landscape photography, reflective metering is the only way, and everything will average out close to 18% gray anyway. "Automatic" exposure requires reflective - the meter cannot be separated.
In studio work, I invariably use incident metering: not only because I can (I use a separate meter anyway) but averaging could easily NOT be the way to go: A model in a black dress in front of a dark background will appear to have a starkly white skin in a slightly darker than medium gray dress and slightly darker than medium dark background.
BTW ... Two "primaries"? - Only if there were two precisely equal light sources. Separate metering of each light source is only useful in determinig lighting RATIOS. For the overall exposure, turn all the lights on, and take a meter reading.... Whoops!!! Zone System followers excluded..!
Ed Sukach, FFP.
And in addition to the single incident reading not helping with the contrast range you must also be aware of where the reading is taken, and whether you are dealing with negative or positive materials. If you are working with negative material a single reading in the sun will usually result in underexposure of up to one stop, whereas a single exposure in the shade will give overexposure of about one stop. Therefore the best way to work is to take two readings, one in the shadow and another in full light, and average the two. If you must work with just one reading a quick and dirty approach is to double the EI for shadow readings and halve it for readings in full light.
Originally Posted by David A. Goldfarb
On the other hand it is best to base your exposure on a single reading in full light when exposing transparency material.