Five tips about exposure that will save your ass at your next shooting

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No matter your skill level, when you think you know everything, there’s always something new that will surprise you. Have a look at this five tips about exposure, you’ll probably find some interesting food for thoughts.

Perfect Exposure

You cannot take a frame and say “this is the perfect exposure”, for a simple reason: “there is no such thing”. A perfect exposure is the effect the photographer intended to get. Perhaps you wanted more dark tones or more highlights? Good for you, as long as that result is exactly what you wanted to obtain out of your picture.

If there is no perfect exposure, what is the light meter telling me? Easy answer: the meter is telling you that the midtones of your picture are located in the very middle of the dynamic range of your film/sensor. This evaluation is used in order to preserve the “significant” part of the information that are supposed to be recorded on the film/sensor.

So, assumed you know the picture you want to have as a final result, just espose accordingly to your expectations.

Metering mode

Matrix, spot, center-weighted, etc. What is the best one to use? None of them.
There is no best one because they are just different ways to measure the scene in front of you and decide which is the appropriate (not the best) exposure settings.
The metering is influenced by the measurement itself and corrected by the appropriate EV compensation.
Metering mode and EV compensation are not to keep in consideration if you manually expose the picture.

EV Compensation

EV compensation is the “correction” you want to apply to the auto metering. It works only in P, S, A modes on Nikon cameras (P, Av, Tv on Canon) and it’s totally ignored in M mode.

As just said if you manually expose, there is no compensation applied because you directly tell the camera what to do.

Reciprocity

If you are familiar with exposure setting you know that it can be expressed with three parameters: ISO sensitivity, Shutter Speed, Aperture. You should also know the relationship between those three parameters and how they are related to each other, right?
Let’s have a quick recap on that.
We assume that the ISO sensitivity is fixed (we tend to assume this condition because in the past, shooting film, it was not possible to change the ISO speed during the shooting, but only when changing rolls) and we try to get the very same exposure changing shutter speed and consequently adapting the aperture. Let start with a ISO 100 (irrelevant), 1/30 sec, f8. We can get the very same exposure with all the equivalent settings on this table.

Shutter Speed Aperture
1 sec f44
1/2 sec f32
1/4 sec f22
1/8 sec f16
1/15 sec f11
1/30 sec f8
1/60 sec f5.6
1/125 sec f4
1/250 sec f2.8
1/500 sec f2
1/1000 sec f1.4

Just remember that this won’t work properly if you shoot faster than 1/1000sec or slower than 1sec. It’s called “reciprocity failure” and requires you to adjust your settings according to the film/sensor you are using.

Latitude

The latitude is the degree of over-exposure or under-exposure that can be recovered from an image, during post processing (or development). Just remember that negative film records information in the highlights and slides/digital sensors better record in the shadows. Therefore, in doubt, overexpose negative film and underexpose digital sensors.

Do you have any more tip or suggestion about exposure you want to share? Don’t be shy and drop a comment here!