Lens depth of field calcs

[Bob Salomon]

DoF charts and calculators are sort of meaningless for LF since there is no distance scale on the lens/camera.

Sinar probably has the best "calculator" built into its focusing system. The GG is the only reliable measure.

- Leigh

Linhof buids an interchageable DOF calculator into several of their view and digital view cameras as well. And they work at more then one image ratio. So Sinar was not the only one with this function. And, if you don't have a Linhof or Sinar the Rodenstock pocket DOF calculator will compute both DOF and Scheimpflug for all formats from 35mm to 8x10 at ratios from 1:1 to infinity and give the exposure correction necessary for a ratio when required. So any view camera user can have this function for less the $50.00!

BTW, The DOF and Scheimpflug calculations from the Rodenstock calculator do not require a distance scale on the camera or lens. The calculator has a mm scale on both sides and the system works by measuring the difference between the near and far points that you focus on by using the scale on the calculator. The difference between those measurements is what the calculator uses. It then indicates where to place the back again by using those points and the scale lets you determine where that point is on the bed or rail.

[Jan Becket]

The Rodenstock DOF calculator works nicely for large format because it uses a calculation that is independent of lens focal length and distance scale. I’ve carried one for years. I glued a thin metal scale onto one side of my focusing rail and when composing the image, use my focusing loupe to note the difference in mm between the far and near points I want sharp. Then I set the camera halfway between those two points and consult the Rodenstock DOF table. Any lens with a 6mm difference between near and far points, for example, must be set at f/32. There is also a very nice iPhone app, Optimum CS Pro, which uses the same calculation method but which allows one to be more or less conservative in the size of the circle of confusion.