Auto Exposure

Some thoughts about 'AUTO' Exposure

Four typical lighting conditions

The exposures below were made with a Minox LX, shutter speed set to "A", and Minox tripod when necessary. When first using a new "auto exposure" camera, I have found it useful to expose a roll of film in a variety of situations using 3 ASA settings for each scene - the nominal film speed, half the speed, and twice the speed. Examination of the negatives should give you an idea of the best speed to use when in automatic exposure mode.

In a "point and shoot" mode, without serious metering, it is hard to imagine better exposures than those obtained in a variety of situations, some difficult. All shown below were from a single roll. Considering the wide range of luminance conditions, it is amazing that the automatic exposure system of the Minox LX (and C) produces near optimal results in each.

Relatively uniform light distribution with little important shadow detail is a situation in which excellent results are provided by -

the "f/16 Rule"
metering a "gray card"
using an incident light meter, or
an automatic exposure camera

Extreme luminance range, with exposure influenced by a predominance of one extreme, to the disadvantage of the other. If the camera's meter sees relatively equal amounts of each, neither may be optimally exposed. In this case the ceiling needs more exposure, and the "outside" high values, less. I suspect the high values are too far up on the shoulder of this particular film to provide good local contrast, so giving the ceiling more exposure would only worsen the situation. Lowering the density of the high values with "minus" negative development will lower the overall contrast, producing a muddy effect.

With an automatic exposure camera, slight changes in the position of the camera will significantly affect the overall exposure.

Wide luminance range in very low light situation. A long time exposure which increases the probability of reciprocity failure affecting the contrast. As with the above illustration, the position of the camera has a bearing on what the meter "sees" and is a major factor in the overall density of the negative. This exposure was probably as long as the LX permits, requiring, of course, the Minox tripod. (I carry, in my pocket, three little plastic "shoes" for the Minox tripod, so as not to mar sensitive surfaces.)

Diffused, soft, relatively low level light (EV 4 to 10). The automatic exposure reacted to the dominance of lighter values and underexposed the dark and poorly illuminated beams. Knowing that significant shadow detail was present, and that the camera metering system would react to the dominant white walls, setting the camera for a one stop longer exposure (lower ASA film speed - remember I had intentionally set the film ASA one stop higher) would have provided near perfect exposure for the dark beams, while hopefully not pushing the walls "over the shoulder". Situations like this generally benefit from spot metering and careful exposure calculation, so it is a pleasant surprise to see such good results from an "automatic" exposure.

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The exposures below were made with a Minox LX, shutter speed set to "A", and Minox tripod when necessary. When first using a new "auto exposure" camera, I have found it useful to expose a roll of film in a variety of situations using 3 ASA settings for each scene - the nominal film speed, half the speed, and twice the speed. Examination of the negatives should give you an idea of the best speed to use when in automatic exposure mode. In a "point and shoot" mode, without serious metering, it is hard to imagine better exposures than those obtained in a variety of situations, some difficult. All shown below were from a single roll. Considering the wide range of luminance conditions, it is amazing that the automatic exposure system of the Minox LX (and C) produces near optimal results in each.

		Relatively uniform light distribution with little important shadow detail is a situation in which excellent results are provided by - the "f/16 Rule" metering a "gray card" using an incident light meter, or an automatic exposure camera

		Extreme luminance range, with exposure influenced by a predominance of one extreme, to the disadvantage of the other. If the camera's meter sees relatively equal amounts of each, neither may be optimally exposed. In this case the ceiling needs more exposure, and the "outside" high values, less. I suspect the high values are too far up on the shoulder of this particular film to provide good local contrast, so giving the ceiling more exposure would only worsen the situation. Lowering the density of the high values with "minus" negative development will lower the overall contrast, producing a muddy effect. With an automatic exposure camera, slight changes in the position of the camera will significantly affect the overall exposure.

		Wide luminance range in very low light situation. A long time exposure which increases the probability of reciprocity failure affecting the contrast. As with the above illustration, the position of the camera has a bearing on what the meter "sees" and is a major factor in the overall density of the negative. This exposure was probably as long as the LX permits, requiring, of course, the Minox tripod. (I carry, in my pocket, three little plastic "shoes" for the Minox tripod, so as not to mar sensitive surfaces.)

		Diffused, soft, relatively low level light (EV 4 to 10). The automatic exposure reacted to the dominance of lighter values and underexposed the dark and poorly illuminated beams. Knowing that significant shadow detail was present, and that the camera metering system would react to the dominant white walls, setting the camera for a one stop longer exposure (lower ASA film speed - remember I had intentionally set the film ASA one stop higher) would have provided near perfect exposure for the dark beams, while hopefully not pushing the walls "over the shoulder". Situations like this generally benefit from spot metering and careful exposure calculation, so it is a pleasant surprise to see such good results from an "automatic" exposure.