11-09-2005, 10:18 PM
My understanding of depth of field is decnt but i have a question. Since focal length of lens is a factor of how shallow DOF you are going to be getting, is it accurate to say that if i had a high res picture and cropped most of it out and zoomed in on a subject there would appear to be shallower dpeth of field. Even if the origninal picture didn't seem to have such a shallow DOF is that just something that appears to the human eye becasue it isnt focused close enough to a speciic area?
11-10-2005, 12:20 AM
Well, the more you zoom in, the less that everything would be in focus (or, put another way, the more out-of-focus everything will look). So something that's marginally in focus in the background could become quite out-of-focus in a blowup. That's why the concept of the "circle of confusion" entered the forumla for depth-of-field -- it takes into account how big the target is going to be blown up, and the larger it gets magnified, the tighter the circle of confusion needs to be in order for something to still look acceptably sharp after being blown up.