Following on from my previous post on comparisons between meters, I thought it important to point out that HOW you use your meter has a significant effect on the exposure you get on the film. There are basically two ways to meter a scene, but a few variations on how those measurements are actually taken and interpreted;

The two main ways of taking a light reading are Reflective and Incident. Reflected readings are measurements of how much light is falling ON THE SCENE and Incident readings are measurements of how much light is falling ON THE METER. Spot meters measure small areas, but are still reflective types and when you take a reading through the camera lens (TTL metering), you are also taking a reflected reading. The trouble is, your choice of subject, or the angle that you shoot from, will influence the brightness that the camera reads. For instance, If I point my camera at a bunch of trees from thirty feet away, I will probably get a reasonable reading from the camera. If I then walk up to the nearest tree and lie underneath it, pointing the camera up through the branches at the sky, I will get quite a different reading, even though the light levels are the same.

In another scenario; I have in front of me two garage doors. One of them is painted black, and the other is white. If I stand some distance away, my reflective reading will average out the lights and darks, giving me an exposure somewhere in between. If I then walk towards the garage doors and take a reading from each, I will have TWO OTHER readings, even though the light levels are still the same.

This kind of subject influenced reading happens on sunny beaches, snowy landscapes, stage photography, night photography, or whenever you photograph any object, scene or person with a predominance of dark tones, or light tones. Given the infinite range of everyday lighting situations and possibilities for error, it is amazing that most shots come out at all. The reason they do, is because film is so forgiving, especially if you are scanning from your negatives and working on the images in photo-editing software. When I say film, I am referring to black and white, or colour negative films. Colour transparency film is far less forgiving and needs more careful metering.

The other method of metering  I mentioned was the incident reading. With this, there is usually a white plastic cone which goes over the light cell and this then allows the meter to read the light falling on the meter, and this is not affected by the tone of the subject. Incident readings are a quick and very accurate way of establishing a reading and are correct in most situations. If used in a back lighting situation, they will favour the shadow tones and give you an exposure which will show the lit areas as overexposed, so use them intelligently.

There is one rule when taking incident readings, and that is that you must point the cone from the scene towards the camera, -not towards the light source. The reason the white thing is a cone, and not a flat disc, is so that in side lighting, one side will be lit and the other shaded, the meter can then average them out. If you point the meter at the light source, it will not take shaded areas into account and you will have an underexposed shot.

If you have a meter with the facility for taking both types of reading, you can take two readings beginning with an incident, then decide if the reflective is giving you a proper mid tone. I usually take an incident and check that against a reflective reading off the grass, or tarmac on the road, both of these are very close to mid grey.

In certain weather conditions, fog for instance, or snow scenes on a grey day, the light remains constant for a number of hours and one meter reading will be sufficient for many shots. Take one incident reading and the light will be the same for every shot.

Spot metering. The spot meter is an excellent invention, but needs careful thought when being used. Typically it will take a reflected reading from a small area, indicated by a circle in the viewfinder of the meter. Anything outside of this area will not be metered, though they do pick up a bit of stray light if you have areas of brightness nearby, or are pointing into the light.

Some people think that all you have to do is take one reading from the shadows, and another from the highlights and put your setting right in the middle. This can be done, but it will depend on how high your bright areas go. Are you reading off a white painted door, or the clouds nearest to the sun? A far more accurate way to do it is to read the exposure for the darkest tone that you would like detail in and underexpose from that reading by two stops.

The important thing to remember is that exposure determines shadow detail and development determines highlight detail.

Just let that sink in a bit; Exposure determines shadow detail and development determines highlight detail. There is no shadow detail that can’t be rendered on film if given enough exposure. Leave the shutter open long enough and the film will record light that your eyes cannot detect. Okay, we’ve got that, but what about contrast? Well, if you have exposed so that the shadow detail will produce some pale greys on the negative, but you have areas where a lot more light reached the film, say for instance, a gap in dark woodland with a sunlit area beyond, this area will have obviously received an excess of light. This will only become unprintable if you keep it in the developer long enough for it to go to black. You don’t want that, you want a dark grey that you can print through, so the answer is to cut back the developer so that this doesn’t happen. I’ll be covering this subject in my next post.

Metering through the camera lens (TTL). This is a quick and practical way to get your exposures pretty close to correct as long as you understand a few things; What you point the camera at for the picture, doesn’t have to be exactly the same thing you point it at to take a reading. For instance, if you were shooting tall buildings in the city from ground level, you would most likely be pointing the camera up and getting lots of sky. Point the camera at the building, excluding sky, take the reading and use that for the up shots. If you are shooting a band on stage, exclude the lighting rig from the frame when you take the reading, then set it and fire away.

For street shooting, a 35mm camera is ideal, but you won’t have time to take a reading as you compose the shot. Think about the tonality of the scene, take a reading from something typical, then set it and forget it.

Metering in low light.

Metering in situations where there is low, even light only requires a good incident reading, a reciprocity chart and a tripod. Metering in situations where there are areas of deep shadow, coupled with hotspots of intense light, such as a concert needs a different approach. Uprating is commonly used in these situations, but this creates negatives of higher contrast, requiring very careful metering. Whenever I see images online and the photographer is claiming that the film was rated at 12500 ASA / ISO or some such high number, my first thought is; Yes, but where did you meter from? If the shots are taken at a concert, or some dark restaurant or club, there will be areas of deep shadow and very bright spots of light. In that kind of situation, a 12500 ASA reading from dark clothing in the corner of the room will give pretty much the same exposure settings as a 400 ASA reading from a well lit face. TTL metering will give you a result, but if the shot is important, then a carefully taken incident reading would be better.

Outdoors in changeable weather conditions: If you have one of those days when the sun is in and out every two minutes messing up your readings, remember that the exposure will only drop by one to one and a half stops when a small cloud comes over. Proper storm clouds will take much more light away, but a typical British summer day with fleeting clouds is easy to meter; If you meter the grass for the sunny areas, the shadows from the clouds will be 1.5 – 2 stops darker than mid grey, but if you meter for the grass when the cloud comes over, the sunny patches will be 1.5 – 2 stops brighter than mid grey. Meter the scene according to the look you are after.

Go out and try these methods and let me know how you get on. If there are any other lighting situations you are having difficulty with, then please leave a comment or question.

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