Sorry if I hijacked the PAD thread so here is a thread to discuss DOF.
First, let me recap my question for those that didn't see it. I asked the question if anybody uses any sort of technique or guideline to determine what aperture they need to set a DOF of a certain size for a give focal length.
Let me start of by asking is their a difference between DOF and bokeh? In my mind they are the same. DOF is the area you want clear in the shot while bokeh is the area you want blurred. If I want a 1 foot area around my focus point clear versus the image to start to blur 1 foot after my focus point am I talking about the same thing? In some discussions it seems that DOF and bokeh are referred to as two separate things. Is my understanding correct?
Below is two examples of different DOF. The first shot of the bird is at 220mm f/5.3. It seems to have a very narrow DOF and I wanted to keep the focus on the bird (I know the focus seems to be behind the bird instead on it but hopefully this still illustrates my point). How have you'll come to learn that if you are going to take a 200mm shot at a bird you need to set an f stop of x.
In the second picture is a shot of two swans (i guess they are swans???). This was taken at 85mm f/4.5 but seems to have a much larger DOF. If I was able to take this at 2.8 or 1.4 do you'll just happen to know where the DOF would end if my focus point is the closes swan? If so, how did you'll go about learning this? Just through repetition or by some other means.
** I'm not sure on the rules on posting multiple images so I made them smaller then what we post on PAD. If I need to use smaller images let me know. Thanks