How do you keep the focus?

[BetterSense]

I don't shoot a lot of portraits, but when I do, I use a 35mm or my RB67. I see a lot of portraits on this site with very shallow DOF. I don't understand how you maintain the subject in the precise position to keep the focus around their eyes. Do you watch the ground glass carefully, then when you have everything lined up, slap the film holder in, yank the darkslide, and hit the cable release? I don't see how you could work with the subject that way, so if you pre-focus the camera, and leave a film holder in and darkslide pulled, then I just don't see how you can keep the subject in the plane of focus when DOF is only a few centimeters. It seems like it would be much easier with an SLR, but few people seem to use large-format SLRs.

[Vick Vickery]

VERY STILL subjects!

[Leigh]

Head clamp.

- Leigh

[Joanna Carter]

Head clamp

… like this:

[eddie]

I see a lot of portraits on this site with very shallow DOF. I don't understand how you maintain the subject in the precise position to keep the focus around their eyes. .

threats! lol

[Leigh]

… like this:

Yep.

Work fine last long time.

- Leigh

[altair]

I'm interested in the answers to this question as well.

[Ari]

First, I explain to the person, briefly, how the camera works, and what they must do to make the shot successful.
Then I compose, frame, and focus.
Once all three elements are in place, I tell the person not to move, put in the film, wait for the expression I'm after, and trip the shutter.
If I judge that eye-to-lens distance hasn't changed, I quickly pop another one.
Usually, on the first or second shot, the person moves too much, and that's how they learn that it's a game of millimetres. After that, works usually proceeds very well.
Easy as pie!

[Jeremy Moore]

Get better models who understand what the process is - they need to be aware of their own bodies and movements.

The string trick is a good one, too. I don't like to use it during the process of making portraits, but at the beginning to show them depth of field - "only the 1/3" in front and 2/3" behind the knot on this string will be in focus" then go through the motions and re-put up the string to see if they moved with them trying to stay still. Almost everyone will and then if you re-do it they are much better.

Portraits w/ large format are much more a partnership between photographer and model.

[Vlad Soare]

Make sure the subject is seated in a comfortable position. People can hold still for very long times if they're comfortable.