View Full Version : Sinar P2 8x10 DOF scale for idiots
Hi all,
You know that Sinar trick with the focus far, focus near, zero the scale and transfer the angle to the rear standard thingy? I don't get it. And why is it always exactly 2 stops to roll in??
I know there are previous threads on this but I am a very, uh, lets say "right-brain" kinda guy and if anyone says anything about circles of confusion, I will get confused! I don't like numbers either....
Anyone know how to talk to special people?
Thanks.
erie patsellis
20-Dec-2010, 13:32
Well, it's pretty straightforward.
Focus far, zero scale, focus near and read off required aperture. Then move back 2 stops to expose. (to shift the actual focal point to the center of the DOF range needed)
Practice it for a while and it becomes second nature.
If you're talking about movements (swings/tilts)then that's not what it's for. Depending on whether you have an F, C or P, the procedure is slightly different. Tell us what you have and maybe somebody can help more.
Bob Salomon
20-Dec-2010, 13:58
Not a "Sinar trick" Linhof also uses a version as do some of the other monorail cameras.
Jeff Conrad
20-Dec-2010, 19:44
The mathematics are really very simple, and the same principle was used on hand-camera DoF scales long before it appeared on LF cameras. For an explanation, see the Wikipedia article Depth of field (http://en.wikipedia.org/wiki/Depth_of_field). It's discussed in the section Focus and f-number from DOF limits (there actually are two sections with that name: the second gives a more detailed explanation, including the derivation). The section Zone focusing explains how the principle is applied to hand-camera lenses; you should notice a remarkable similarity to what you described in your original post. Though the small-format people say otherwise, the technique also works on tilt/shift lenses with tilt, provided one recognizes that the marked distances are no longer meaningful.
I've used this approach to set focus and f-number on every type of camera I've every had, and honestly don't know how to do it any other way.
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