cunim
Well-known member
OK, I think I understand it. Disclaimer: This is my own amateur analysis, and may be totally wrong.
The problem is flex between the extension box for longer lenses and the camera body. The camera itself is not misaligned.
To position the 120 and 150 mm Apo Digitars, Arca supplied extension boxes that mount to the rear of the 3Di.
That puts the heavy back on a long lever arm. The camera body flexes on top, where the box/back assembly attaches to it. This results in a bit of "droop" in the sensor relative to the optical axis. Droop is, of course, equivalent to backwards tilt.
With a 72 Apo Digitar - no extension box - there is no flex and everything lines up nicely. Same with the longer lenses on the monolith. No extension boxes, no flex, and no misalignment.
Conclusion: If you are using a 3Di with extension boxes and a heavy digital back, expect a bit of tilt misalignment.
Note: I see pictures of new Arca R-mount Apo Digitars which have spacer tubes between the lens and camera instead of on the rear.
Lenses Schneider-Kreuznach APO DIGITAR N 5.6 120mm for Rm3D
Much less weight hanging off the spacer that way so I expect flex is not a problem. Anyone using the tube spacer?
The problem is flex between the extension box for longer lenses and the camera body. The camera itself is not misaligned.
To position the 120 and 150 mm Apo Digitars, Arca supplied extension boxes that mount to the rear of the 3Di.
That puts the heavy back on a long lever arm. The camera body flexes on top, where the box/back assembly attaches to it. This results in a bit of "droop" in the sensor relative to the optical axis. Droop is, of course, equivalent to backwards tilt.
With a 72 Apo Digitar - no extension box - there is no flex and everything lines up nicely. Same with the longer lenses on the monolith. No extension boxes, no flex, and no misalignment.
Conclusion: If you are using a 3Di with extension boxes and a heavy digital back, expect a bit of tilt misalignment.
Note: I see pictures of new Arca R-mount Apo Digitars which have spacer tubes between the lens and camera instead of on the rear.
Lenses Schneider-Kreuznach APO DIGITAR N 5.6 120mm for Rm3D
Much less weight hanging off the spacer that way so I expect flex is not a problem. Anyone using the tube spacer?