Wednesday, April 8, 2009

Life, Love and Part 3: The Aperture

Remember last time how I said the ISO was kind of like your pupil and the bigger it is the more sensitive it is too light? Well now you can forget that because this might just confuse you. The size of your pupil may better be suited toward the aperture size.

When talking about apertures it’s important to remember that bigger isn’t always better, a rule that applies to so many aspects of life I don’t even know where to begin. Let’s go back to the eye ball example. Your camera is like an eyeball, this being the case the aperture (often represented as by values like f/2.4, f4 and f8 called f-stops) is kind of like the pupil. The larger the pupil the more light gets in. In your camera the size of the hole that lets light in is known as the aperture. See the analogy? Cute yes? Truth be told how your aperture effects your camera is more of a combination of both the pupil and your eye lids. I’ll explain, remember that time you thought that chick at the midnight bowling alley was really hot? But you couldn’t quite tell so you squinted your eyes a little to sharpen the image and stared for a long time until your eyes adjusted to the lighting at which point the chick noticed you staring at her and he came over and the last thing you said before he beat you up was “Dude, I thought you were a chick!”Same thing, minus the beating.

A smaller aperture makes the images sharper, like squinting you’re eyes. A larger aperture increases the depth of field, meaning that one point at a certain distance will be in focus and all objects around it at varying lengths will be blurry and out of focus (hence the field looks deeper). Here’s a fun exercise: Go down to the local police department (note the activity has to be performed this way or it won’t work, no deviations) and stand in the parking lot facing the entrance. Now hold out your hand and extend your middle finger. Focus on your finger so everything in the back ground is out of focus. Now squint your eyes (shrink your aperture). Magically you can now see the background just as sharp as your middle finger; you’ll notice men approaching you. Run.

The image on the left was taken with a larger aperture (smaller f-stop), while the image on the right was taken with a smaller aperture (larger f-stop). You can see the difference in focus.

Understanding f-stops (remember f-stops are technical talk for the size of the aperture) is even worse. It’s like trying to understand a woman, it just makes no sense. Think about this: F/1.4 vs F/8. Which is bigger? F/8 of course. WRONG. F/1.4 is larger. The smaller the number the bigger aperture hole. Contradictory and confusing? Yes, you understand my woman analogy then.

Further more if you are trying to control the shutter, the ISO and the aperture things can get pretty difficult. Especially if you are managing them all through controls on the camera menu. Some lenses will allow you to manipulate the shutter speed by a ring much the same way you would control the focal length, but most the time you’ll have to do it through camera menu controls.

I’ve found the aperture to be the most difficult piece to master. It’s like having a thumb located on your coccyx, I’m sure it has some useful applications but for now let’s keep it simple.

What you need to know: Larger apertures let in more light. Smaller apertures bring more of the image into focus. Twilight was a horrible and ridiculously long movie based on faulty vampire logic. For the most part letting your camera decide the aperture is enough.

How to apply this: If you are taking a landscape photo you want more of the landscape to be in focus. You know that setting on your camera that has a picture of a mountain? That’s landscape mode, if you select that then your camera will shrink the aperture size to bring more of the image into focus.

This image had a larger aperture, the focal point was placed in the center so you'll notice that the top and bottom sand trails are a little hazy.

Sometimes you’ll want to take a picture of several objects a varying length but want them all in focus so you’ll shrink the aperture to like f/22. Now you click and … … … your shutter speed has been decreased to like 10 seconds. Remember, less light is getting through so the camera has to compensate opening the shutter longer. Otherwise the image will be black. I have not yet found a practical use for f/22. Instead I’ve found that about f/16 or a few f-stops slower are enough to bring every object into focus given decent light. Conversely if you wanted to make everything in your subject blurry except for the main subject, you’d simply take the aperture down to its smallest number and snap the shot.

Other applications are to simply compensate for lighting the same way you would with the ISO or shutter. If it’s too bright, shrink the aperture (remember, smaller aperture = larger f-stop), if it’s too dark, well I’ll let you do some detective work on this one Lou.

That’s about all there is to know about apertures at this point. You should know that your aperture size is dependent upon your current lens. Pay attention to F-stops when purchasing, if you are getting a telephoto lens (longer zooms) then you will want smaller F-stop numbers because as the lens extends less light is able to get through. Smaller f-stops will also increase the price of these lenses (think about those ginormous monocular you see on cameras at basketball games, they’re so big because they need to allow for more light to enter).

For your next exercise head out to the beach, get four really hot girls (or guys), tell them you’re shooting a magazine called “four really hot girls (or guys)”. Stagger them at different lengths, focus on one and then take some pictures at different f-stops. Notice that even though through the lens the other sexy folk are out of focus, if the f-stop is large enough everything will be in focus on the image. Now that you have taken their pictures, tell them that you are not really from a magazine but are a wiccan and that you’ve stolen their soles with your magical soul stealing device.

There you have it, the holy trinity of the camera: The Shutter, The Iso and the Aperture full of grace.

Want some more lecture on the aperture?

Check the wiki

Or listen to some other guy's rantings