How to meter correctly for photography with a flash?

IvanMyring · Feb 8, 2014

I recently bought a canon ftb, and lens, and was wondering how I set it up correctly to use a flash. How do I know what aperture to use with a flash to get everything properly exposed?
I would use a manual flash (like the yongnuo 560 ii) but obviously, using film, it would take time and money to experiment. Can you think of any good guides explaining?

compur · Feb 8, 2014

The first place to look is the owners manual for the flash. Some flash units have auto-sensing and some don't or they have different modes of operation.

The basic factors are aperture, distance to subject and film ISO. The camera's shutter speed must also be set at or below its flash sync speed.

JustJazzie · Feb 8, 2014

You could always invest in a handheld light meter to measure exposure with before you waste film.

dubiousone · Feb 8, 2014

Not sure if the FTb has TTL (Through the lens metering) or not, have to look that up. If not, using a flash on manual isn't that hard. On most manual flashes, there will be a little wheel or a scale. First thing to set is the ISO. Then, set the camera shutter speed to whatever is uses for flash, usually something like 60, maybe 125. Look in the manual. Then you need to know the distances you will be shooting. Look on the scale and you will see aperture and when the scale is set for the ISO, there should be a range under one F number that goes from 4-10Ft, something like that. There's usually another for 10-to30 or a similar distance depending on the power of the flash. Set the camera's aperture to that setting. Now, here's the hard part;

Depending on the scene, backlit, light background/dark subject, the other way around, reflective surfaces, some parts of your photo may get under or over exposed. With experience you can make a pretty accurate guess. When the film is processed and printed, depending on who, some of that can be corrected. If it's too far one end or the other (over/under exposure) the processor will do the best they can. Another handy tip is to 'bracket' which means you take one photo using a middle of the road guess, one a little over exposed and one under. Usually one or more will come out depending on how good your guesses are!