Relationship between the apeture and depth of field?

Question

i just need to know what the relationship is between the aperture and depth of field.

Answer 1

Here's a link with a very good explanation:
http://www.mir.com.my/rb/photography/fototech/htmls/depth.html

Answer 2

The apeture is the opening in the lens that allows a specific amount of light in. Depth of field is the term given to the focal quality of a photo graph. A smaller apeture opening allows less light into the camera to expose the film, therefore the items that are closest to the camer will be in sharper focus than the background images. A larger apeture opening allows more light in and thus enabling more 'depth' in the focal aspect of the photograph.

A small aperture is generally used when you want to take a photo that has strong foreground focal point, such as a portrait.

Hope this helps!

Answer 3

i can't remember mathematically but i do know that widening the aperture reduces the depth of field. If you take in a wider cone of light at the lens (because you're short of light) then the rays at the object diverge more quickly, so focus away from the focal point collapses more quickly.

maybe if you google Will Hossack Optics or something like that you'll find some good lecture notes on this

Answer 4

The smaller the aperture the greater the depth of field. Conversely, in order to do that, you need a lot of light.

Answer 5

I'm mostly using digital now, but if I remember correctly it goes like this. Small aperture means long exposure, so more information writes to the film thus bigger depth of field. Large aperture means short exposure therefore smaller depth of field. Its all about film sensitivity. Think of it as having a look at something and remembering it later. The longer you look at a scene, the more information you remember about that scene.

Answer 6

Aperture, focal length, focus distance (i.e. distance to subject), and film/sensor size all affect depth of field. Three of these, you control (or can control), while the fourth is a fixed value for any given camera.

In general... depth of field gets larger as aperture number gets larger (i.e. smaller opening), depth of field gets smaller as focal length increases, and depth of field gets larger as focus distance increases. These all interact to give the resulting depth of field for any given photo.

Depending on your equipment and your settings, DOF can range from millimeters to miles. If you have an SLR with a DOF Preview button, you can kind of play with settings and learn what to expect. Otherwise, it's all practice, and eventually you'll have a pretty good idea of what any given shot will look like DOF-wise before you take it.

Answer 7

Also the further the subject from the lens, the greater the depth of field. With the same lens, focusing on a near object gives less depth of field than focusing on a distant object.

Answer 8

smaller aperture (f/big number) = greater depth of field

so
for f/2.8 you will have a smaller DOF than at f/11 because f/11 is much smaller aperture than f/2.8.

also keep in mind about how close are you to the subject.

Answer 9

The smaller the aperture (higher f-stop number), the greater your depth of field is. That is to say that if you have your lens set to f11, your range of focus might be 15 feet, and if you have your lens set to f5.6, it may be 5 or 6 feet. Higher f-stop= sharper, longer focus. lower f-stop= shorter focus.

Answer 10

The relationship is INVERSE