Beginner Tips: Aperture

Image courtesy of Photoluminary

To continue with some beginner tips I wanted to talk about aperture.  If you know what aperture does and how to use it your photography will improve and be even more enjoyable.  There is a setting on most cameras to control aperture only leaving all other settings in auto, called aperture priority mode (Av: Canon, A: Nikon, see manual for other).  First, you need to understand what the aperture does.  In every lens there is a fan-like circle that controls how much light comes into the sensor, which is called the aperture.  With a small number like 1.8 the hole is very large and let's in a lot of light, making it easier to shoot in low light with a faster shutter speed.  A high number like 22 makes the hole rather small and allows very little light to reach the sensor, making your shutter speed longer.  Now, there is another factor that is in play and that is Depth of Field (DOF).  When you use an aperture of 1.8 you're going to have a very shallow DOF and most everything, besides what you've focused on in that plane, is going to be out of focus.  This is very effective when shooting portraits or when the background is distracting.  If you want everything to be in focus from near to far, an aperture above 8.0 is usually effective.  Many photographers have found the "sweet spot" in each lens as to not lose quality and still have a deep DOF, and it's usually around 8.0-10.  If you want to slow the shutter speed on purpose, using an aperture of 22 will do just that.  I like to play around with the apertures from 8-22 and see if there is much difference in a certain scene.

In addition to talking about aperture, lenses are also tied in to the subject.  Lenses with really low aperture numbers are referred to as fast lenses and usually carry a high price tag.  For example, a 70-200 mm lens with image stabilization and a constant aperture of 2.8 is a very fast lens and is about $2,500.  Whereas a similar featured 70-200 mm lens at a constant aperture of 4 (still a pretty fast lens) is priced around $1,200.  Both pretty expensive lenses, but you get the idea.  If you're looking for a really fast lens at a low price I would strongly recommend a prime lens like the 50 mm f/1.8 (The number after the f is the lowest aperture possible).  This lens is by far the best bang for your buck at around $100.  If you ever shoot indoors or in low light this lens is a must.  Also, a great lens for portraits as the distance is how our eyes see and won't distort any part of the image.

As I've said before, the best way to learn is to go out and experiment on your own.  The best way to see the difference in aperture is to focus on something around two feet in front of you with the background further away, take the picture at different apertures and compare.