Hyperfocal Distance - Nope I just don't get it, please help

[jamesev]

I've read the dPS article on hyperfocal distance.

I put my numbers into DOFMaster

50mm Lens, Subject Distance 5m, f1.8 because I wanted the subject in focus and the background out of focus.

It gave me Near Limit 4.67m, Far Limit 5.38, so a total DOF of .71m.

However it then says the Hyperfocal*distance is 70.2 m

I would have thought that with a far limit of 5.38, anything at 70.2m would be extremely out of focus.

Can some one please explain?

[RLucas]

Depth of field is not only dependent on on aperture, it's also dependent on distance to subject. The farther away the subject is, the deeper the dof.
At that aperture, if you focus on a subject that is 70.2 meters away, then the dof will be from 35.1 meters to infinity.
Hope that helps.

[RecurrentNerve]

What it means is that if you focus at a point 70.2m away (rather than on your subject), everything from half that distance to infinity will be in focus.

If you are thinking of just photographing your subject at 5m away, ignore the bit about hyperfocal distance.

[jamesev]

Originally Posted by RecurrentNerve

What it means is that if you focus at a point 70.2m away (rather than on your subject), everything from half that distance to infinity will be in focus.

If you are thinking of just photographing your subject at 5m away, ignore the bit about hyperfocal distance.

Ok thanks for clearing that up. So its more about the use of a particular lens for longer distance focusing. (above the 5m I am using)

Oh yeah I just varied the distance to subject by a few order of magnitude values keeping the for the same lens / focal length and same f number and the Hyperfocal Distance was fixed.

[RecurrentNerve]

Exactly. Change the f-number to, say, 11 and you'll see that the HFD is much closer, so for example with a landscape shot you'd be able to get more in focus.