what is the relation between aperture and

[sid_iift_2005]

depth of field?

[virkinus]

The bigger the aperture, the lower the depth. The smaller the aperture, the higher the depth. A big aperture lets in more light, so the depth is not possible in the same measure.

[Bill in Iowa]

Both answers are true. If you want to go into the technical details, it has to do with something called "circles of confusion".BTW, this is why one might squint when not wearing glasses. Your eyelids are creating a smaller aperture.

[bigtymberto]

aperture is like the sizing of a hole... the larger the hole, the larger the aperture (but you get a smaller number lik 2.8); the smaller the hole, the smaller the aperture (and you get a larger number like f22)...now, the larger the aperture, the smaller the amount of sharpness there is in front and behind your subject that is in focus. But if you want everything to be sharper, you have to set a smaller aperture.

[vturiserra]

Small aperture = more depth of field, and vice versa, but...And that's an important "but". If you need the greatest depth of field, don't use the smallest aperture stop. Use the stop next to the smallest. The reason is that in smaller apertures, image sharpness is more and more degraded by light diffraction.Diffraction is a physics phenomenon that affects all kinds of wave transmission (light, sound, etc.). Waves tend to curve near object borders. As it has to do with physics, not with lens quality, it cannot be avoided by any means. The only way to reduce it is by not using the smallest aperture. So, if the smallest aperture in your lens is f/22, you should use f/16. If you have a high speed film and the sun is very strong, you may have to use a neutral density filter to darken the image a bit.