Focussing a 4x5?greenspun.com : LUSENET : Large format photography : One Thread
I have just started using a Super Speed Graphic 4x5. This camera has front movements, but no back movements. I am having trouble with depthe of field and critical focus. I would appreciate help with focussing technique. Especially in seemingly complicated situations, like when I have a vertical foreground subject (a tree) and wish to have the whole forest in focus. Thank you very much! Jon
-- Jon Paul (email@example.com), July 07, 1999
DOF is a real issue, thanks to the longer focal lengths which have to be used on larger formats. Scheimpflug principle can help but not in all situations. The situation you describe is a classic one where there is not much to be gained by using tilts and swings to shift the plane of sharp focus. You're probably better off using the hyperfocal distance and stopping down. The tilts work well when you have a dominant plane which is not parallel to the film plane, for e.g., in a landscape where the receding plane of the ground needs to be held in sharp focus.
Re DOF when you tilt, the simplest way is to stop down and check sharpness on the GG. Harold Merklinger's page has some info which might help (I think it can be accessed through the useful addresses link on the main lf page). Basically, when you use tilts, your DOF becomes wedge shaped (as opposed to the situation when you don't use tilts i.e., lens, film plane and plane of focus parallel in which case DOF extends in front of and behind the plane of focus). As you stop down the angle of the wedge increases. At the hyperfocal distance, you will have a DOF above and below the plane of focus equal to the height of the lens above the plane of focus. In other words, if the lens is x above the ground (assuming you want the plane of the ground in sharp focus), then at the hyperfocal distance (which is dependant on how much you stop down), DOF will extend to x above and below the plane of sharp focus. You can calculate the hyperfocal distance from the acceptable circle of confusion and aperture.
Hope this is of some help. DJ
-- N Dhananjay (firstname.lastname@example.org), July 07, 1999.
I'm going to throw in something that most of us find obvious, but someone who is just starting out looking at a ground-glass image may not have thought about - yet. Use a loupe, a magnifier or even drugstore reading glasses. A ground-glass image is very deceptive, things "look" sharp, but aren't. I say this, because for the first 30 years of using 4x5 and 8x10 cameras, in the studio and out, I focused by eye. It's only the last 10 or 12 years, that I've realized how much more accurate things are when a loupe is used. [Gee, I wonder how I got away without one for so long. Must a been awfully lucky}
-- Dick Fish (email@example.com), July 07, 1999.
Newbie problem #1: Thinks he/she needs to use all the movements at once
Newbie problem #2: Does not use a good tripod
Newbie Problem #3: Does not shoot polaroid
Newbie Problem #4: Does not stop down enough
Newbie problem #5: Pushes the shutter before the camera stops vibration from insertion of the film holder.
-- Altaf Shaikh (firstname.lastname@example.org), July 09, 1999.
No. Newbie problem #1 is not ardently searching out a competent LF photographer for guidance. And then listen and do. James
-- james (email@example.com), July 09, 1999.
Some of us apparently live in places where you couldn't hit another LF photographer with a nuclear blast. I'm learning my own pretty much in a vacuum...except for the internet...which doesn't make the vacuum so vacuous.
-- John H. Henderson (firstname.lastname@example.org), September 23, 1999.