Hyperfocal focusing with tiltsgreenspun.com : LUSENET : Large format photography : One Thread
I'm about to make the leap into large format photography and am doing extensive research. I've studied the usual focusing tutorials (Large Format Pages, Merklinger, Simmons, etc) so I have a theoretical grasp, if not practical experience.
I have been told of a focusing method used by a landscape photographer. The method is attractively simple but strikes me as specious. Here it is:
"I worked out the hyperfocal distances for all my lenses and recorded them for F11 and F22. I them focused on these distances and marked them on the rail for when I move the back. For most landscapes with a fairly flat field all you need to do is focus on the foreground apply your tilt to the background and refocus to the hyperfocal distance which is marked on the bed."
I think I can see the rationale behind it. He focuses on foreground, then tilts for background. He then refocuses at hyperfocal, preserving the tilt.
However, given that tilt creates a conical depth of field around the tilted subject plane, I would have thought that conventional hyperfocal distances no longer apply when a tilt is active. Therefore focusing at the hyperfocal distance is not likely to be optimal.
What do you think of this approach? Is it just plain wrong?
-- Leigh Perry (firstname.lastname@example.org), April 03, 2002
With respect....Whatever happened to the time honored technique of just drawing down the dark cloth around your GG and using a good louple to tell you if you had sharp focus or NOT. This Techno-stuff is getting a little bit tiresome. I'll bet that Brady and Jackson never heard the term, hyperfocal distance. They did it anyway. (:-)
-- Richard Boulware (email@example.com), April 03, 2002.
Richard has the idea, although a little theory can save some time and trouble in the field.
My understanding of hyperfocal distance is that it relates only to film and lens planes that are parallel. Once tilt is applied to either standard, HF DOF goes out the window.
-- Michael Mahoney (firstname.lastname@example.org), April 03, 2002.
the Hyperfocal Distance, i.e. the focus point where DOF extends from infinity to the nearest most plane, is indeed not applicable to a tilted view camera in the same way. It's substitute is a more general DOF-concept, as you have already pointed out.
-- Thilo Schmid (email@example.com), April 04, 2002.
It's much simpler in practice than in theory. Go make some photographs. Use a loupe to check your focus. You'll understand it much more quickly and you'll have some pictures too.
-- Mark Sampson (MSampson45@aol.com), April 04, 2002.
Mark, are you saying that you endorse the hyperfocal method I described?
-- Leigh Perry (firstname.lastname@example.org), April 04, 2002.
It's good to know the hyperfocal distance for your lenses because there are situations where swing and tilt can't be used. Beyond that, the hyperfocal distance is a good starting point. For many landscape subjects if you start at the hyperfocal distance and then add a bit of front tilt you'll immediately have universal focus.
-- Carl Weese (email@example.com), April 04, 2002.
This will get easier once you get your camera and start practicing what you read about. I assume you have looked at these 2 articles on the LF page:
Once you have applied the tilt (use the GG to focus, Merklinger will just slow you down and confuse here!) select the near & far limits in your 'wedge-shaped' DOF required, and use the method of measuring the distance you need to move the focus knob to focus the near and far limits (the second article above). The nice thing about this method is it works the same for all focal lenghts. I don't use a scale, I just go by how many mm per 1/4 turn of the knob and do it by 'feel', so I can stay under the dark cloth. As others have suggested, you can also just stop down using a loupe on the GG until all limits are sharp. Sometimes this can be difficult in dim light though. I agree with all here who say that the practice is much easier than the theory!
-- Gary Frost (firstname.lastname@example.org), April 04, 2002.
I got a kick out of some of the responses! With my 4 x 5 and a 90mm lense (f6.8) at f22 with the standards parallel, I focus on my cases at 11 feet. Therefore from 5.5 to infinity (in theory) everything is in focus. One thing is for sure: from 5.5 out to who knows where, is in focus. I then use rise or fall for final adjustment; however no tilts! I do this all the time! This technique is not necessary with my 150, 210, and 305mm lenses. With those I use the movements for focus!! For me the technique works because all my 90mm shots are done at f22. It works for me. I hope you find what works for you!
-- phil sweeney (email@example.com), April 07, 2002.