Photography Course

Lenses: aperture and shutter settings

Lenses come in different “focal lengths”

Here’s what five different lenses sees through your view finder:

All shots were taken from the exact same spot with the same camera body.

I simply doubled the focal length (from LEFT to RIGHT) and used the same exposure (f16 @ 1/500 using Fujicolor 400).

So the question then becomes “How do we achieve correct exposure?”

Study this and learn it and you will KNOW how to control exposure.

THAT’S RIGHT, THERE ARE TWO DEVICES TO CONTROL EXPOSURE….

THE SHUTTER, is usually a curtain-like device just in front of the film. Think of a shade pulled down on a window, and then quickly open it and close it. FOR AN INSTANT THE ROOM WAS FILLED WITH LIGHT and the length of time that burst of light filled the room is shutter speed! That is basically how a shutter controls the amount of light getting to the film.

Now stay with the above notion. The time the shade was open determined - to some extent - how much light came into the room - but so did the SIZE of the window! That window opening acted as…

THE APERTURE, which is built inside each lens and here is how it controls the light:

Now for some clarification on shutter speeds. Looking at the photo below, you will see inside the red circle, the numbers in white are the shutter speeds in fractions of a second (i.e. 30 = 1/30, 60 = 1/60). This is the time taken from when the shutter opens to when the shutter closes, after you’ve press the shutter release.

Moving from one speed to the next one halves the amount of light that enters the camera. Moving the other way, to a slower shutter speed, doubles the amount of light that enters the camera. This change from one speed to another is called moving a stop. For instance, moving from a speed of 1/30th to 1/60th of a second is going 1 stop faster, and from 1/60th of a second to 1/250th of a second is moving 2 stops.

HERE IS A RULE OF THUMB FOR PROPER EXPOSURE OUTDOORS:

First take the film speed number as your shutter speed (100 ISO = 1/125th of a second or, if your film speed is 400 then the shutter speed would be 1/500th of a second for instance), your aperture setting is:

For bright sunny days and the sun is on the subject. f16.

For overcast, cloudy. f8.

Sunsets and sunrises, low light. wide open @ 1/30th

These are basic starting points that usually work. The film package also has some excellent, basic exposure suggestions.

So you have two methods of controlling exactly how many light rays get on the film and if you understand the above you then understand how to control exposure for different types of film. Re-read it until you understand it, because this is the crux of exposure for daylight photographs. You must learn these settings - even if it means memorizing them because they never change. The sun always emits the same degree of light.

In order to become more sophisticated with exposure control you need to learn how to use a light meter. This can get very complicated because there are so many light metering systems out there, and so many ways of using those meters. I submit, after 40 years of shooting, that the only true metering system you NEED to master is the light metering system offered in any good SLR camera. It reads the light coming off the subject matter, through the lens you are using, and is controlled by the film speed you have already set that meter to. It simply is the most sensible, accurate way to meter those light rays. SLR meters are getting more advanced all the time offering “spot” metering (you can zero in on one particular spot on the subject, get the right exposure, and lock in that setting and make your photo) … overall metering, reflected metering, incident metering, ……and on and on. No longer is it necessary to “bracket” your exposure ( shoot one frame over by one stop, one frame at the indicated exposure, and one stop under the recommended exposure). I quit bracketing twenty years ago and have not exposed a frame improperly.

Therefore I will not get into other methods of metering. All of the recommended exposures from now on will be based on thru-the-lens metering with an SLR camera.

For now, I would suggest that if you have a SLR camera - with built-in metering - you get in the habit of reading the light off the palm of your hand. It is a very accurate method of metering.

In short here is how it works. If your subject matter is in the shade twenty feet away, then create that shady lighting on your palm

and take the reading with your camera’s meter.

If your subject matter is in bright light, again create that light on the palm of your hand

and read that light with your camera’s meter. This truly is a very accurate metering method.

Enough with Exposure Control, Shutter Speed, and aperture. Lets learn about FILM