Guy Stewart
20-Dec-2004, 15:28
I would like to know if these is a way to use an electronic focusing system on a large format camera which would replace ground glass focusing. I enjoy portraiture, and a device which would eliminate the need for cumbersome, time-consuming focusing would greatly improve spontaneity, etc.
I know that sometime ago, Linhof sold an electronic range "finding" (as opposed to "finder") system, but apparently it was not successful, and, even if they were available on 8 x 10, traditional split-image rangefinders are hard to use.
However, I beleive Linhof's electonic sysytem was sold at least 10 to 15 years ago, and it occurred to me that someone might know of a newer system that works.
For example, would it be possible to affix some kind of a portable beam-emitting rangefinder to or on the camera's bed, or, in the case of my Sinar P2, the tube to which the front and rear standards are mounted and along which they can be moved forwards and backwards?
The process would work something like this (I think; I took optics in high school, and that was a long time ago.)
1. The subject remains still.
2. An aesthetically pleasing composition is selected. (I tend to like shoulder/head shots.)
3. The subject continues to remains still.
4. The camera is sharp-focused through the ground glass (while the subject is not moving.)
5. The subject continues to remain still.
6. The front lensboard-to-subject distance is measured. (I would probably use a point about 1/3 of the way back from the tip of the subject's nose to the rear of the skull and use 125th/at least f16 for some depth of field. My strobes can easily deliver enough light for this, even using 50 ASA film.) Obviously, whatever sort of "beam" (acoustic, infra-red, etc) is used, it can't annoy the subject or show up on the inage.
7. Thus, the photographer now has a subject which is in sharp focus at a defined lensboard-to-subject distance. (It would seem to me that this is now a fixed focus camera calibrated to a fixed distance of x feet.)
8. The range finder is "set" for that distance and emits a signal to indicate as much.
9. The range finder is capable of emiting a signal once that front lensboard-to-subject distance changes.
10. The session begins.
11. The subject could move about normally, and to "focus" on the changed position of the subject, the entire camera (my tripod is mounted on large industrial wheels with quick-locks) is moved forwards and backwards until the range finder emits a signal that the previously defined/entered lensboard-to-subject distance has once again been established. (Not to belabor the point, but once the mass of the camera body itself locked into "focus," the front lensboard would not be touched.)
Is this feasible? If so, does anyone know of any relatively small range finding device which could be mounted on the camera bed/optical bench? Is there anything out there which is accurate, say to 1/4 or, better yet, to 1/16th of an inch? .
If anyone wants to yack on the phone, feel free to call - collect.
Thanks.
Guy K. Stewart, Jr. (561) 659 - 1810 West Palm Beach, Florida
I know that sometime ago, Linhof sold an electronic range "finding" (as opposed to "finder") system, but apparently it was not successful, and, even if they were available on 8 x 10, traditional split-image rangefinders are hard to use.
However, I beleive Linhof's electonic sysytem was sold at least 10 to 15 years ago, and it occurred to me that someone might know of a newer system that works.
For example, would it be possible to affix some kind of a portable beam-emitting rangefinder to or on the camera's bed, or, in the case of my Sinar P2, the tube to which the front and rear standards are mounted and along which they can be moved forwards and backwards?
The process would work something like this (I think; I took optics in high school, and that was a long time ago.)
1. The subject remains still.
2. An aesthetically pleasing composition is selected. (I tend to like shoulder/head shots.)
3. The subject continues to remains still.
4. The camera is sharp-focused through the ground glass (while the subject is not moving.)
5. The subject continues to remain still.
6. The front lensboard-to-subject distance is measured. (I would probably use a point about 1/3 of the way back from the tip of the subject's nose to the rear of the skull and use 125th/at least f16 for some depth of field. My strobes can easily deliver enough light for this, even using 50 ASA film.) Obviously, whatever sort of "beam" (acoustic, infra-red, etc) is used, it can't annoy the subject or show up on the inage.
7. Thus, the photographer now has a subject which is in sharp focus at a defined lensboard-to-subject distance. (It would seem to me that this is now a fixed focus camera calibrated to a fixed distance of x feet.)
8. The range finder is "set" for that distance and emits a signal to indicate as much.
9. The range finder is capable of emiting a signal once that front lensboard-to-subject distance changes.
10. The session begins.
11. The subject could move about normally, and to "focus" on the changed position of the subject, the entire camera (my tripod is mounted on large industrial wheels with quick-locks) is moved forwards and backwards until the range finder emits a signal that the previously defined/entered lensboard-to-subject distance has once again been established. (Not to belabor the point, but once the mass of the camera body itself locked into "focus," the front lensboard would not be touched.)
Is this feasible? If so, does anyone know of any relatively small range finding device which could be mounted on the camera bed/optical bench? Is there anything out there which is accurate, say to 1/4 or, better yet, to 1/16th of an inch? .
If anyone wants to yack on the phone, feel free to call - collect.
Thanks.
Guy K. Stewart, Jr. (561) 659 - 1810 West Palm Beach, Florida