Backlighting is often used to create atmospheric photographs in the form of silhouettes or rimlit shots. I have been using it a lot over the last year as well. Lately, I have been trying to expand on the technique and create sidelit conditions. Sidelighting is very helpful if you want to show texture in your subject. Or in my case: if you just want to create a more dramatic image of a common subject.
Metering for sidelighting is not much different from metering for backlighting and frontlighting. Just put the camera in M mode, (spot)meter the brightest part and set your exposure so that the brightest part gets the tonality you want it to have.
The other (darker) parts will then easily fall into place. If you use evaluative metering (or matrix metering), you should underexpose relative to the metering by about a stop for sidelight and about 2 stops for backlight. Otherwise, the meter will try to render the (shaded) subject a medium grey, therewith severely overexposing the background and lighter parts of the subject.
The image above of a roe deer was meant to be a backlit shot. I was hidden in a heathland beneath a large berch tree, looking straight into the sun, when two female roe deer came running towards me at about 3 o’clock. One of them stood still for a split second, allowing me to take this sidelit shot. And as the camera was in M mode, I did not need to compensate the exposure I had set for the expected backlit shot.
Roe Deer; Canon 1D Mark III w. 500/4 IS and 1.4x; 1/250s at F5.6 and ISO 400; Gitzo tripod