Skip to main menu | Skip to content

What is a light "stop"?

The term "Stop" would be better described (in my never humble opinion) as a "Light Stop".

Theoretically, a one stop increase equals close to double the amount of light being exposed on the film. Therefore, one stop decrease equals clost to half the amount of light being exposed on the film.

As a photographer, it is the best term we have to tell other what we did and, more importantly, make relative adjustments to our cameras as we capture images.

I will not go into any detail about "stops" as part of the development and printing process - just with relevance to the actual point in time of capturing the image.

Ways to adjust the light stop

There are three main techniques for adjusting "stops"

An increase of one stop in any one of these areas (and by that I mean - let more light in) theoretically means you are doubling the amount of light coming into the camera.

If you have an automatic light meter in your camera, there are very good reasons for changing the stop in one area after the camera has made its best guess at the correct combination.

This is why most modern semi-automatic cameras give you (at least) the options of:

Changing Shutter Speed

In the process of writing.

Changing Aperture

In the process of writing.

Choosing Film Speed

Note that I use the term "choosing" not "changing".

Film speed is usually set at a single stop (a constant) for the life of the film in the camera and it's usually the speed that the film is rated at (printed on the box / film canister).

The main reason for this is that to change it part way through would make it difficult to develop after you have finished the roll. If you are using a conventional developing company (eg. you leave the film at a express film lab or the Chemist) then they will probably not develop it correctly even if you ask them and they agree.

For this reason I have not gone into detail about the impacts of changing film speed. Suffice to say the principal is the same. The important thing is to choose and load a film with a rating compatible with the type of subject you will be expecting to take with this roll.

More on this can be found on the film speed page.

Related / Other Pages

...and also... (external links - these open in a new window)
© bpresent computing or the artist whose work is depicted
Valid XHTML 1.0 Transitional Mostly CSS validated but hacked for IE!