Digital Photography Tip Number 27....Large Aperture Value Means Larger Depth Of Field
Tip #27) Large Aperture Value Means Larger Depth Of Field.... When you have a large aperture value like F22 or larger, you will get the most depth of field(focus) as possible and your focus point won't be as critical. Aperture values and aperture opening sizes can be confusing.
A large aperture like F22 closing down the aperture opening, and allows less light in the camera, but gives more depth of field, like looking through a small hole. I don't know the science behind why the depth of field is increased with a small aperture opening, but its the same reason as when you look through a small hole and you can see things more clearly, for those of us with bad eyes and can't see without glasses or contact lenses.
This activity will only work if you have bad eyes and need glasses or contact lenses to see far, so you people with good eyes are out of luck, you can't try this fun activity. To start, grab a piece of paper and a pin or tack, and poke a small hole in the paper. Take off your glasses or contact lenses, and then look through the small hole, with the paper as close to your eye as possible. You should be able to see distance objects clearly, without your glasses!! Now you don't have to wear glasses anymore, just stick pieces of paper with small holes in front of your eyes and you have 20/20 vision again, who needs glasses or Lasik surgery, you have your paper with small holes to make you see perfect again.
Similar Confusing Terminology
If you did the activity above, you should understand a little better, that a large aperture value like f/22, gives you a small aperture opening, like you can see in the photo collage above, and a deeper depth-of-field(focus). Something that has similar confusing terminology is electrical wire. A size 12 gage wire is larger than a 28 gage wire. So to sum it all up, you just have to remember a large aperture value like F22, gives you larger or deeper depth of field(focus), but a smaller aperture opening and less light into the camera.