Hi in the warmth of the summer!
I try to find out how to make DOF knobs for my cameras, an Arca Swiss 6x9, 1982 model, and a Century Graphic 6x9.
I have looked at Hayashi's DOF knob
and wonder about the reference point. Hayashi uses a mark on the tension control knob. But when I loosen this knob on my Arca, it moves as I turn the focussing knob. Is there something I have overlooked or misunderstood? Or is this knob just different on more recent Arcas? To work as the "carrier" for the reference point, it would have to snap into a well-defined position when loosened, or?
Another option I have thought of, would be using a turn counting dial mounted onto or instead of he focussing knob. It would imply a counting dial that could be zeroed, preferably by the push of a button, as a second choice by turning back to some sort of indent or mechanically defined stop. Would anybody know of a source for such a knob?
I have browsed the hardware places listed on this site
as well as some others in Europe, but without success. At least, I can not determine from the specs if they have a way of zeroing.
I bought their model 15-1-11 by mail-order, believing, that the little black thing that can be seen at the bottom of the picture, was the desired zeroing button; but it is just a lever to adjust friction.
I feel that for 6x9, just a millimeter scale is not precise enough. It would have to be to 0.1 mm.
Good light! - Hening.