Aperture & Depth of Field

In this post, I’ll be talking mainly about how your camera’s aperture setting affects “depth of field,” the portion of your image which appears to be in focus.  Those using SLR cameras and the right lens really have it quite easy, while point-and-shoot users are a bit more limited.  And for those of you with P&S cameras without any manual or semi-automatic options, controlling depth of field is even more tricky, but it can still be done.  Lots to talk about, but first a little background information.

Your camera’s aperture, or f-stop, is a relative number.  In other words, it’s a ratio of two other numbers, and that ratio only means something for your particular camera, lens and settings.  Only relative comparisons can be made between different cameras and lenses.  This aperture ratio is simply the focal length of your lens divided by the diameter of the aperture (the opening that lets light into your camera).  All right, had enough?  Here are the things you need to know:

  • f/4 = f4 = F4 (same thing, written three different ways)
  • Lower f values = larger openings = more light (and “shallower” depth of field)
  • Higher f values = smaller openings = less light (and “deeper” depth of field)

Simple, isn’t it?  Here’s are two examples showing a page in an old (1936) Webster’s dictionary.  These shots were taken with a P&S, using macro mode and no zoom.  I focused on the phrase “To misconduct oneself” at the bottom of the page.  The photos capture about 7″ of the page, from bottom to top.   I set the aperture at two different values and let the camera choose a shutter speed.  Nothing else was changed between the two shots.

Can you see the differences?  First, compare the hinges (upper left corner).  Notice how the f/2.8 shot is kind of soft, while the f/8.0 shot is better defined.  Next check out some individual words.  In the f/2.8 shot, the word farthest up the page (in the middle column) that can be read is “mis-comfort,” and that’s about 1-1/2″ up from the focal point.  The f/8.0 shot gives us an image that can be read all the way up to the word “mischief-making,” about 3-1/2″ up.  That’s quite a difference!  So which one is better?  Neither!  That’s right, it just depends on what you’re trying to accomplish.  But now that you see the kind of impact a simple change in aperture can have, let’s talk a little about how to make it work for you.

First, check out your camera to see if it has an “aperture priority” mode (or “A” or “Ap” or “Av” mode or something like that).  If it does, lucky you!  Now, find your user manual and learn how to use it.  It’s really quite easy.  Experiment a little bit, do some tests like I did above, and see what works best for your product and the type of image you’re trying to produce.  Along the way (just for fun), pay attention to the relationship between aperture and shutter speed.

So why would you want an image with a shallow depth of field?  Well, if done properly, it can certainly give the photo a more “artistic” look.  It can also be helpful if you’re trying to highlight one particular item, or even part of an item, in the composition.  Or maybe your background is just plain ugly and you want to hide it!  Whatever the reason, a shallow depth of field can make your photos a bit more special.  See for yourself — here are two pretty cool examples from Etsy shops erinf115 and KaelinDesign.

But what if your camera doesn’t have the aperture priority option and you want an image with a shallow depth of field?  Don’t worry, all hope is not lost.  Regardless of what you’re shooting, you can trick your camera into selecting a low aperture value by putting it in “Sports” or “Action” or “Kids&Pets” mode (whatever mode your camera has that’s supposed to be for moving subjects).

Besides varying the aperture, there are a number of other shooting tricks that allow you to control depth of field, but that’s an entirely different discussion best left for another day.  Meanwhile, see what you can do with your aperture adjustments.  I’d love to see some of your results!

Until next time … Happy Shooting!

3 thoughts on “Aperture & Depth of Field

  1. Thanks for this great information. Can’t wait to put my P&S thru a workout with your great suggestions.

    I am liking the look of the blog today, btw. Really like the Nice Folks feature and appreciate that you took our insights about black bg into consideration.

    blog on.


    • Thanks so much for the article, so appreciated. I love the way you explain things, it makes it seem so much easier. I just recently got a SLR camera and am still struggling with AV, P etc settings and depth of field issues. Thanks so much, you are a real teacher.
      Jeanne :))

  2. Once again, a clear concise explaination of an intimidating camera application. By this time, you realize, we expect nothing less…LOL. Thanks again…great piece…keep up the wonderful work. We appreciate your time and efforts. As Jeanne C. says, ‘you are a real teacher!’

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