As many would know, film photography is so different to digital photography. In some ways however it is similar as Adobe Photoshop is basically a dark room, though with film we cannot see or check the photos we are about to take.
In this way you only know if it is a good or bad photograph once the film has been developed and then you can see how they turned out.
On a few occasions I have been tricked by my light meter thinking that my photo was exposed correctly, but it simply was not the case. The light meter inside the camera is designed for that purpose, to help you correctly expose your photo, right?
EHH - wrong. But right...sort of, errr......
If one is not familiar with the way it works (such as myself) then things can go horribly wrong as soon as you start taking photos with several different light plains.
For example if you are taking a photo of someone outside in the sun through the inside of a window, you light meter may give you incorrect readings. If the bulk of the photo is on the inside of the room, the light meter will adjust accordingly and give you an incorrect exposure reading.
Take for example this photo (enlarged from a scanned contact sheet, not an actual print):
(and this photo, girl falling asleep on bus)
In this case I wished to take a photo of a friend as she drove in her car. A large portion of the photo was on the sky outside. It was also a very bright day.
When I activated the light meter to help me program appropriate camera settings, I followed its instructions without thinking.
When I developed the film I was shocked to find that the photograph hadn't turned out quite how I planned it. In this instance the light meter must have adjusted itself to compensate for the exposure outside of the car, making what was inside of the car way too under exposed. This setting may have worked for a flat outside shot, but since there were two distinguishably different exposure settings, it did not.
Unless this is the desired effect, I now understand better how to use my camera so that it doesn't fool me when I am trying to take photos like this.
If I could re take this same photo, I would frame out the sunny sky (ie; point the camera at her chest/lap/face only) to trigger the camera's light meter into using the correct exposure settings for the inside (subject) before taking the photograph. When you have your correct frame, leave the settings as they approximately were. You could experiment with changing settings slightly but without over compensating for where your camera wants you to go. Now you should have a correctly exposed subject (and probably a way overexposed background). But nevertheless at least now you can probably see your friend driving in her car.
This my friends, is how you trick your light meter.
Use at your own peril :)