The following passage is from Ansel Adams' The Negative:

"In most photography we record light reflected from the subject, rather than the light incident upon it."

Here, Adams states that reflective metering was more common during his career. This puzzles me for two reasons:

  1. In-camera meters weren't very common, as far as I am aware, during most of Adams' life. The first camera with a built in meter was a Zeiss-Ikon Contaflex from '35, but couples, built-in light meters seem to be far more common in cameras from the 1970's and later, although mostly in 135 format.

  2. Especially because Adams shot large format, the lack of built-in reflective meters would mean Adams needed to use a handheld meter. This would, logically, enable him to do not just reflective metering, but also more precise incidence metering. As most know, incidence metering is not affected by reflections or colours which would generally fool the reflective meter.

With this in mind, why does Adams say the reflective meter was more commonly used? Were there any limitations or decisions to choose reflective over incidence metering?

  • Adams shot both roll film and sheet film. The reason he preferred sheet film for some work was that it allowed him to process each photograph independently according to his "Zone System" tone reproduction technique.
    – Stan
    May 31, 2019 at 19:12
  • How does one take an incident reading of the light falling on a mountain several miles away over near impassable terrain and then return to the camera to take a photo before that light has changed?
    – Michael C
    Feb 17, 2020 at 21:24

5 Answers 5


The quote doesn't talk about metering but about recording light, i.e. photography (literally).

most photos are of reflective objects, rather than of light sources, the occasional sunset notwithstanding and even in this case, the clouds, sky, and landscape are usually more interesting than the sun itself.)

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    The Negative; Adams, "My philosophy of photographic procedure is based on the evaluation of the light reflected from the subject and not on the evaluation of the incident light. I support this philosophy on the basis of esthetic [sic] and emotional factors more than on physical considerations."
    – Stan
    May 31, 2019 at 21:49

The vast majority of Adams' most significant works were of landscapes in which much of the scene was miles away from the camera over very rough terrain. While Adams did often spend hours or even days reaching a remote spot where he placed his cameras, spending another two days to traipse over to an area that would be in the photograph to take an incident reading would be mostly useless, since by the time he got back to the camera position the light would almost certainly have changed in some way.

Even if the incident meters that were available to Adams from the 1950s on had been available to him in the earlier years when his reputation was established, he would not have had much use for them. The quote above from "The Negative", which was published in 1981, is evidence of that. "The Negative" has its roots in a similarly named publication from 1948 which was before incident meters were widely available.


An incident light reading is the same (very similar to) as a simple grey-card reading. They both assume an average scene illuminance. That's a big assumption for the creative photographic interpretation practiced by Mr Adams.

Adams used an SEI reflection spot meter with a very narrow angle to record actual different light levels that reached the camera rather than a reading of the source light shown on the subject.

A photograph records the amount of light reflected from the subject to show how the light affects the subject not the light that is incident on the subject. We want to record the effect of the light.

If we take an incident reading of the light shining on a dead black subject how do we know how much light will reach the film? We don't. If we take an incident reading of the same light shining on a sheet of white paper subject next to the dead black subject, how do we know how much light will reach the same film? We don't.

Therefore, we measure the reflected light to ensure we capture the differential effect of the reflected light on the subject.

I don't recall him making any kind of statement about the commonality of the meter type having a bearing on his work. I don't see how this statement makes that point. He was saying how it should be done for photography. In the day, a Weston foot-candle meter (measuring incident illuminance) was a standard photonic tool but it was not sensitive enough to be used for reflection readings until the tools were more developed.


The light meter came on the scene in the early 1930’s. Reliable light meters suitable for use by photographers came about in the late 1930’s. previously photographers uses tables and intuitions. Western Electric (Weston) and General Electric (GE) ran tests on film speeds and established speed values that were the forerunner of ASA. The ASA speed rating system along with others, evolved into the methods used to establish ISO film ratings’. The incident method was not in common use until the early 1950’s. Incident in this connotation is an “old French” word for about to happen. The bottom line is, getting the exposure correct was and is an evolving technology.

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    Don't you think it's the English word "incident" in the sense "falling or striking on something"? M-W says that the word itself is from the Latin for "to fall"....
    – mattdm
    May 31, 2019 at 19:56
  • In his "Description of terms used in this book" Adams defines Incident Light… The light falling upon a subject from a source of illumination—sun, sky, flash or photoflood lamps, reflector, etc. as opposed to Reflected Light…The light reflected from the subject to the spectator or the lens.
    – Stan
    May 31, 2019 at 21:39

The kind of external light meter modern enthusiast and pro photographers know is indeed predominantly of a type optimized for incident light. These usually look like they have a ping pong ball embedded in them.

The common type of external light meter in the 1970s and earlier, was optimized for reflected light metering by pointing it at the scene. Recognizable by having a honeycomb like array of glass or plastic lenses on one side.

So while every serious/technical photographer and their dog must have had external light meters back then, these were not the kind much liked by studio photography enthusiasts today.

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