Dan St. Gean , Nov 07, 2006; 01:56 p.m.
I have been shooting some portraits and more recently shots of my new baby
that have been tight head shots. I have been finding that some of the larger
f stops have been too much to keep the subject in focus. Unless the subject
is square to the flim plane--which looks stiff and boring to me--I'm getting
one of the eyes OOF. To get adequate depth of field to cover a tightly
cropped portrait with a 105mm lens, what should I be stopping down to? I
looked at the depth of field calculators online and found with a close subject
to camera distance and 105mm lens, I was really surprised to find shallow
depth of field all the way out to f32!
The question I have for you folks is what kind of f stop will render the
background OOF while retaining the area of sharp focus deep enough to cover
the critical component of the subject--the eyes?
If you have some real workd images to demonstrate, that would be helpful.
I just set up a home studio using what I learned from the strobist.blogspot
site and have found that 5.6 left precious little DOF.
Dan
Ocean Physics 
, Nov 07, 2006; 02:15 p.m.
With a longer lens you can stop down more and get the same amount of background blur with more depth of field.
JF R , Nov 07, 2006; 02:20 p.m.
If you want both eyes in focus, while shooting close to the subject you need a big f-stop or a shorter lens. Try it with a 50mm or so, from even closer or sacrifice the focus on the far eye. If you can get both eyes in focus with f32, the background will still be blurred, although the OOF-areas will probably don't look as appealing as with a small f-stop.
JF R , Nov 07, 2006; 02:20 p.m.
If you want both eyes in focus, while shooting close to the subject you need a big f-stop or a shorter lens. Try it with a 50mm or so, from even closer or sacrifice the focus on the far eye. If you can get both eyes in focus with f32, the background will still be blurred, although the OOF-areas will probably don't look as appealing as with a small f-stop.
David Lee , Nov 07, 2006; 02:50 p.m.
if 5.6 is not working, then try 8.0, and the 11.0, but remember that if you are shooting a
"head and shoulders" portrait, any lens will give you the same depht of field. it doesn't
matter if it's a 50mm or a 28mm or a 300mm. different lenses let you get closer or step
farther, but the dof stays the same. that is a fact of life.
Keith Van Hulle , Nov 07, 2006; 03:16 p.m.
You've left out two variables - subject distance and background distance. The first affects your DOF and the second determines what's OOF. With a 105 @5.6 the difference between 5 & 10 feet for subject distance changes the DOF by almost 9 inches. Farther away increases DOF. Maybe you need to get a little further away? f11@5 feet will get you close to a half foot of DOF. You have to consider all the variables.
Dan St. Gean , Nov 07, 2006; 03:59 p.m.
That's kind of what I've been doing. I have been fooling around with the 50 1.8, but the close focusing distance often impedes a frame that is full of the subject. I like the rendering of the slight telephoto, but need to try to get some additional DOF to keep both eyes in focus when closer.
Nadine Ohara - SF Bay Area/CA 
, Nov 07, 2006; 04:54 p.m.
Look up DOF Master, download it, and look up what you need.
David Lee , Nov 07, 2006; 10:54 p.m.
a "frame full of the subject" will have the same dof if you use a constant aperture
regardless of the lens used. that's it. if you use a 28mm then the degrees of coverage
behind will be more than with a 105mm, but dof will be the same. distortion and
compression is a whole different matter. shoot a roll and see for yourself. this came to me
clearly when i started doing close ups.
Al Kaplan - Miami, FL , Nov 07, 2006; 11:08 p.m.
The old traditional method with a large format camera was to use the swings and tilts to change the plane of focus. It was common to focus on the pupils of BOTH eyes, as well as the tip of the chin, even if the head was turned somewhat and maybe tilted doen a bit. You could put an 8 inch (about 200mm) f/4.5 lens on a 4x5 camera, shoot wide open, and both eyes were razor sharp. We've sacrificed a lot of control in pursuit of quick 'n dirty.
MaryBall Pierson 
, Nov 08, 2006; 09:52 a.m.
Step back. I shoot plenty of portraits etc.. at 2.8 or 4. The further back you go - the better your DOF.
Scott Levine , Nov 09, 2006; 10:24 a.m.
http://www.dofmaster.com/dofjs.html
