Scheimpflug Principle technique for close-up workgreenspun.com : LUSENET : Large format photography : One Thread
I'm comfortable with the tilt/swing angle methodology suggested in this forum for use when photographing scenes at a distance (focus far, tilt/swing until near is in focus and then iterate). This technique does not work when doing table top work.
When doing close-up work, the technique I use is to simply visualize the operative planes (focus, lens and film) and estimate what tilt will be required, and use that as a starting point. Sometimes I'll even take pieces of wood, and place them in the planes to help my visualization. My question is simple - Is there a better methodology?
-- Larry Huppert (Larry.Huppert@mail.com), October 05, 1999
I've had good results with the method you suggest.
-- Sean Donnelly (firstname.lastname@example.org), October 05, 1999.
I find that just looking at the ground glass is the fastest way for me. Its easy to see when near/far objects are equally out of focus.
-- Ron Shaw (email@example.com), October 05, 1999.
Don't know if there's a better method than checking on the ground glass after setting your tilts etc. Part of your trouble is the fact that you're doing macro work and the bellows are extended quite a bit. This means that it takes a lot of tilt before you establish a Scheimpflug a couple of feet or so off the ground. The problem is magnified by the fact that you're working very close to the subject, which means tilts change your framing a good bit more than normal. Your hinge line however, changes at about the same rate as for the usual infinity-kind of subjects. All of this means that getting a plane of focus along the ground i.e., parallel to the camera lens axis is going to take a heck of a lot of tilt. Odds are you'll run out of coverage long before that. DJ
-- N Dhananjay (firstname.lastname@example.org), October 05, 1999.
If I don't own a Sinar I would start with the method you describe for a first rough setting of back and front to cross their lines with the desired plane of sharpness at full aperture. Then I look through the ground-glass and close-down to my preferred aperture with that lens and detect the sharpness-range given by this setting. I focus 1/3 past the first (part of) object that I want sharp and 2/3 before the last (part of) object I want sharp. If then something is unsharp which I want sharp above or beneath/left or right I know where and how to tilt/swing or how much more closing down this would require.
If I own a Sinar I can use their patented trick on the focussing knob and read out the necessary aperture between two far ends of the sharpness-range. And I use the method described in their books on the ground-glass get it all horizontally and vertically sharp.
-- Lot (email@example.com), October 05, 1999.
Have you ever read Merklingers Book "Focussing the view camera". Although he does a lousy job explaining his theory, it works perfect, I make a quick scaled sketch of the scene, (this is sketch gives you the exact distance below the lens where the plane of sharp focus intersects with the film plane) then using some look up tables, you will find the proper tilt angle as well as the distance between the lens and film (back focus distance). The sketch will also accurately predict the f stop required to compliment your slanted plane of sharp focus. Of course nothing beats a Polaroid. It takes me about 2 minutes to do the sketch, then I can nail things perfect with the camera in less than 30 seconds... my trial and error way sometimes would take 30 minutes or longer.. although once in awhile I got lucky and nailed it in a few minutes. Good luck....
-- Bill Glickman (Bglick@pclv.com), October 06, 1999.
I've been trying out Bob Wheeler's freeware palm pilot program "vade mecum". I've found it to be a very useful program for helping me predetermine the tilt angle. With some careful measurement, it helps me nail the settings on the head. A great improvement over my previous technique! I do wish the program had a more friendly interface, but that is minor compared to what it can tell you.
-- Larry Huppert (Larry.Huppert@mail.com), October 12, 1999.