Focus issues

[Kauaicrazed]

I still do not get this. If I am shooting on M (I have a 30d) and I would like the background to be blurred but I would also like both people to be in sharp focus and one person is infront of the other person. What aperture would be good for this and where do I set my AF point? I would be using a 50mm lens or 28-105mm lens. I can't seem to get both subject matters in focus...only one is in focus?

TIA for any suggestions!

[gjl711]

It all depends on how all the elements are set up. Background blur is dependent on the distance the camera is from the subjects, how far apart the subjects are, and how far the background is as well. For two subjects you want to have enough depth of field to get both in but narrow enough so the background is blurry.

So you might want to start with What lens your planing on using and the FL you want to set the lens to. So lets say your 30D with the 50mm. Then the subjects and how far apart they are. Lets say 2 feet. This will set what you DOF needs to be. Then the distance you camera will be from the first subject. Lets say 10 feet. You now have enough info to perform a DOF calculation and set you aperture. Comes up with about f/5.6. Now the farther the background the blurrier it will be. If the background is 15 feet behind the subjects it will be a little blurry. If its 30 feet it will be quite a bit blurrier.

Here is a nice little DOF calculator you can play with. Punch in your numbers and play around a bit.
http://www.dofmaster.com/dofjs.html