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Randy Moe
10-Jan-2015, 11:56
I knew my monorail Horseman cameras had tripod mount gearing, but I never used it the way I did the other day. I focused the camera as I usually do, then while looking at GG I rolled the center tripod geared support back and forth and there it was! The whole DOF field easy seen, without refocusing. The zone of acceptable focus was visible, and when it went away.

Call me slow, or what, but it was a revelation to me.

Most cameras don't have this ability. Not the Sinar I have used, not my old Linhof, none of my flatbeds.

Which others do?

rjbuzzclick
10-Jan-2015, 12:49
Calumet CC-400 series have this. Technically it's not geared though, just a friction wheel that's the same as what's on the standards.

Good idea though, actually never crossed my mind!

Sevo
10-Jan-2015, 12:52
Your camera travels through the DOF field by simply moving it forward and back by the maybe 20cm each way the rail? That should not happen unless you are near 1:1 magnification (where camera movement is equivalent to subject movement). One of the Cambos did it (probably the same as the already mentioned Calumet).

Randy Moe
10-Jan-2015, 12:54
Calumet CC-400 series have this. Technically it's not geared though, just a friction wheel that's the same as what's on the standards.

Friction wheels work very well. The C1 uses them, but not for the sliding base.

Maybe there is a flatbed with geared sliding base.

Randy Moe
10-Jan-2015, 12:56
Your camera travels through the DOF field by simply moving it forward and back by the maybe 20cm each way the rail? That should not happen unless you are near 1:1 magnification (where camera movement is equivalent to subject movement).

That is where I was, I am doing more macro in this cold winter.

I have not tried it outside my studio, where everything is basically macro.

Bob Salomon
10-Jan-2015, 14:36
If you use any Linhof Kardan made from the Kardan Super Color JBJ, or later, including the current models, they have a sliding block on the bottom of their rail which, when the head it is monted to is slightly loosened the rail can then smoothly slide over the 18" length of the rail, or longer if the camera has the telescoping rail.

In addition Linhof make some heads that the rail just slides onto. The camera, on these heads, is locked in place with a lever lock. Release the lever and the camera will slide over the length of the rail.

This has been a standard feature on the profile rail Linhof Kardans since about 1977.

For the older round rail Kardans, like the original Super Color and the B the rail can slide front to back by simply loosening the clamping screw on the mounting block. Sinars operate this way also as do any other round rail camera with an encircling clamp.

Maris Rusis
10-Jan-2015, 15:23
I knew my monorail Horseman cameras had tripod mount gearing, but I never used it the way I did the other day. I focused the camera as I usually do, then while looking at GG I rolled the center tripod geared support back and forth and there it was! The whole DOF field easy seen, without refocusing. The zone of acceptable focus was visible, and when it went away....

There is a hidden problem with this approach which may or may not be significant. Moving the entire camera back and forth does not explore the depth of field characterists of any particular image. Because the lens to subject distance is changing each image on the ground glass is "valid" for only that unique lens to subject distance. And the perspective rendition also changes with every change in the lens to subject distance.

The alternative approach is to fix the lens to subject distance and then explore the image depth-of-field characteristics by racking only the back of the camera to and fro. The only time the crucial difference between racking the entire camera and racking just the back of the camera bites me is when trying to do big face close-ups with a view camera. Every change of lens position changes the nose to ears size ratio and the visual composition of the portrait... for instance.

Randy Moe
10-Jan-2015, 15:26
Yes.