DOF example

Here's a quick one today...an example of how DOF can make or break a picture. In the picture below, it is a portrait. When shooting a single head shot, you can get very creative with DOF, but when you are doing more than one person, especially a small group, DOF can easily make or break your shot, especially if you want to be more creative with DOF use.

Details: D700 (full frame) at 200mm focal length, f/2.8. I didn't measure exactly how far I was away from the subject, but I estimate about 8 to 9 feet.


See how DOF (area of focus between the front plane and rear plane) is razor thin? In this case, Ashley is easily outside of that area of focus. How thin is the focus area anyway? How do you calculate this? Simple, just use a DOF calculator. In the above example, the DOF is about 1" to 1.5". Pretty thin for a two person portrait...too thin. But, do able, if you understand what is going on and ensure both person's eyes are on the same plane.

There are a bunch on the web and I personally like this one:
http://www.dofmaster.com/dofjs.html

I also have a cheat sheet for situation where I want to be more precise. Different shots require different level of precision. If I was shooting wider at a shorter focal length, the difference between, say, f/8 and f/11 may not matter much.

Here's another example. Taken with a D700 at 63mm f/5.6 and about 8 feet. In this case, it prob. would be fine at f/4 with some care, and at f/8 you would not notice any difference compared to f/5.6. Why? Look at the DOF calculations for each aperture below. There's plenty of room in the area of focus.

f/4 = 1.16' about 14". Pretty thick, but with three kids, you want to pay a bit more attention.
f/5.6 = 1.64' about 20". Plenty thick
f/8 = 2.35' about 28". Prob. overkill, but there are no foreground objects and the background is just a white sheet, so it really does not matter. (what will matter is how much light f/8 will reduce and change your exposure quite a bit)