I have tried taking a few portraits in my living room, using studio flash. I'm still new to it, so my lighting setups may not be great.
I have found sometimes that I can shoot 3 or 4 shots in a row - essentially identical lighting, pose, camera settings. Sometimes one shot can be superbly sharp while the others seem to have focus problems.
This led me to learn more about how aperture affects depth of field, and in turn how distance from subject plays a part also.
I found an online calculator that will tell you the depth of field given an aperture, distance to subject and camera model.
I have just bought Nikon's 80-200mm 2.8 specifically to work on portraits. I searched Flickr for examples and found this one (not my photo).
The exif info tells me it's a D300 at f/2.8, 80mm and it has approximate distance to focal point = 2.51 (I presume it is metres).
When I enter this info into the focal length calculator it tells me that the depth of field for acceptable level of sharpness is 11 cm.
When I measure my own head, it's approx 22cm front to back. However, in the example photo almost all of the model is in focus. I see some slight blurring at the back of the head but even the fingers seem sharp and these are in front of the face.
How did this photographer manage to get almost all of the model sharp and in focus?
Does it appear sharper because the image has been downsized?
Has sharpening been applied in post-processing?
Am I totally missing something with the maths, or with the photo-taking process? I am almost certain that if I attempt a shot at f/2.8, 80mm at 2.5m from the subject I will have focus problems. (Testing this is my next step of course!)
Thanks in advance for any help, suggestions or insights you can provide.