Beginner's Guide to Manual Photography
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Kurtis Kronk
Brian
N/A
Jul. 19, 2006
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Aperture
For this section of the article, I urge you to follow along with your camera in Aperture priority mode. Once again, to keep things simple, I'll just be discussing aperture on its own merits and save talking about the implications of all the various settings on one another for later.
Simply put, aperture refers to the diameter of the hole through which light passes in your camera's lens. The way aperture is measured may be a little confusing at first. The bigger the aperture (opening), the smaller the f-stop number that represents it. For example, f/2.8 is a common "wide-open" aperture whereas f/22 might be "closed-up." The illustration below shows a lens wide-open, then a half-way closed, and finally closed-up.

Lens Apertures
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Dominoes
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Thumbtacks
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If you want to get overly technical, aperture is measured by:
Lens Focal Length / Size of Opening = f/x
So, my Sigma 50mm F2.8 EX DG macro lens has a 17.8mm opening at most, meaning it has a 'maximum' aperture (read: the lowest f-stop) of f/2.8. Fascinating, I know! you may now put the calculator away.
Another important property of aperture is that it controls depth-of-field (DOF). DOF is the distance in front of and behind the subject which is in focus. The technical aspects of DOF are somewhat complicated so for the time being, I'll focus simply on the basic implications of aperture on your photographs. If you want a shallow DOF, which is helpful to accentuate the subject or make a distracting background a pleasant out-of-focus one, you will want to use a larger aperture (smaller f-stop number). By contrast, if you want to have more of the scene in focus, you can use a smaller aperture (higher f-stop number).
Your aperture setting alone is not the only thing that will control the DOF, however. The size of the camera sensor, lens focal length, and distance from the subject also play an important role. I will save all of those details for a future article, but I encourage you to experiment for yourself.
1 - Posted by
Kurtis
on July 19, 2006 - 3:35 pm
2 - Posted by
jcmarney
on July 20, 2006 - 12:06 pm
Good Read- One comment though. The Sunlight f/16 rule isn't going to work for digital for many cases. Small digicams simply don't close down to f/16, and DSLR's will often start degrading in quality due to diffraction.
There is a good article to familiarize yourself with the effects of diffraction here: http://www.diglloyd.com/diglloyd/free/DigicamDiffr...
3 - Posted by
Kurtis
on July 20, 2006 - 12:32 pm
Good point. I personally never use the sunny 16 rule, but thought it might be a helpful reference for some.
4 - Posted by
blackjet
on July 24, 2006 - 7:31 am
hay kurtis, good article, enjoyed the read....now I just need a camera to try it all out!
5 - Posted by
ty_hot
on February 15, 2008 - 5:06 pm
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