Depth of Field

Another no photo post today I’m afraid, I’ve now forgotten what the sun looks like! I was out doing a bit of remote shooting with the pocket wizards today, I use the PW’s for off camera flash but I’ve recently got a cord that connects the wizards to the shutter release so I can fire the camera from a mile away. Unfortunately my tests yielded some of the worst photos I have ever taken so I won’t be posting any but I’ve ironed out the kinks and should have some up soon.

I did have to use web resource that I haven’t been on for a while as I was trying to do some Depth of field calculations. Depth of field is a term used when talking about how much of a photo is in focus and is not an easy concept to begin with but it soon becomes second nature. Portraits are a good example of photos that have a very low depth of field, they (usually) have a nice background blur with just the subjects face, or more specifically eyes, in focus, this draws in the viewers attention. Landscapes on the other hand usually have a large depth of field so everything is in focus from the foreground to the back ground. There are many factors that you can change to alter the depth of field, the main ones being:

Lens aperture – Lower the f number the smaller the DOF, so f/2.8 has a much shallower DOF than f/16)
Focal length – Wider focal lengths have higher DOF, so 24mm has a larger DOF than 200mm)
Subject distance – As the subject gets closer (or the working distance decreases) the DOF becomes less

Sensor size also plays a part with larger full frame sensors having less DOF than smaller crop sensors but this is not a variable that can easily be changed.

Anyway the simulator I was using, which explains things visually better than I have above is Here. With this DOF simulator you can see the current depth of field and how changing things like aperture and focal length can effect things, this is very useful if you need to know how wide your DOF will be if you have settings X,Y and Z. The site it is on, Liquid Sculpture, is also a great site with some fantastic water drop shots, well worth checking out.