Originally posted by Steve Belcoski Can HFD be used for longer focal length lenses or is it really just for shorter focal lengths and if it can used with longer focal lengths, an HFD is known by app or calculation, how do you know, to the required accuracy, where that is when you are focusing on it?
Yes, the rules for DOF and HFD work the same for all focal lengths, though the concept is somewhat less useful as focal lengths increase. Here are few considerations:
- There is nothing magical or even particularly special about the so-called hyperfocal distance. It is merely the plane of focus where the far DOF is sufficiently distant that your eye can't tell where the focus boundary is.
- If you are worried about near DOF, don't use HFD as the basis for focus. That is a hard rule and why HFD is usually more useful at shorter focal lengths.
- If you are not worried about far DOF, don't use HFD as the basis for focus
- If the gradations on the distance scale are too far apart to zone focus HFD for your intended focal length and aperture, it is probably not a good time to use HFD
- Very few people actually use HFD. Deep DOF with plane of focus at the intended subject is more useful. If the near field is important, the eye will forgive and may actually expect an unsharp far field.
- Near field sharpness is ultimately more important than far and near DOF will usually fail in that respect. After all, there is only ONE plane of critical focus. The boundaries of near and far DOF merely describe the limits within which there is "acceptable" (not too soft) focus.
- Your DOF calculator is your friend and knowing approximate DOF for your subject distance is more useful in planning the shot than precise attainment of HFD
- Extreme near/far with appropriate proportions and optimum resolution is not possible without some form of camera movements and/or some form of focus stacking. With fixed lens axis and focal plane, the laws of optics, perspective, and perception work against you.
Do I ever use HFD? Yes, sometimes, though never for where focus is critical. Do I ever do something similar? Absolutely! Street photography is based on use of a moderate wide angle lens at f/8 with focus set to 2.5-3m. The combination provides about 5 meters of usable DOF. Frame-shoot-smile.
Steve