Focusing Scale Vernier

[glatiak]

I currently use a mm scale on my Linhof Technika V together with the Rodenstock calculator. The bed pointer works ok, but I am wondering if a vernier would be an improvement on my estimating skills for where between the two mm marks the reading actually is? (My eyes are just not what they used to be...) And is there anything out there that would help me create such a thing?

Thanks.

[el french]

Vernier scales can be pretty easy to make. Basically it's just 9 increments in the same space as 10 increments. This site may help: http://www.geocities.com/richardandtracy/sextant05.htm

[Leonard Evens]

I currently use a mm scale on my Linhof Technika V together with the Rodenstock calculator. The bed pointer works ok, but I am wondering if a vernier would be an improvement on my estimating skills for where between the two mm marks the reading actually is? (My eyes are just not what they used to be...) And is there anything out there that would help me create such a thing?

Thanks.

You might consider putting a scale on the focusing knob. Most view cameras use gearing so that a large movement of the focusing knob yields a small movement along the rail. I did this with my Toho FC-45X and I can easily position the standard to within 0.2 mm. I explained how I did it at

www.math.northwestern.edu/~len/photos/pages/dof_essay.pdf

See also

www.largeformatphotography.info/dofknob/

[sultanofcognac]

I'm going to go out on a very thin limb here.

I'd love to make one of those dof knobs for my cameras but my old Arca Swiss rear standard knob has quite a bit of play and I fear this would be more trouble than it's worth.

BUT - I do have a programme on my iPhone called "photocalc" that does an 'interesting' job of calculating depth of field. If anyone else has this could he or she please let me know if I'm totally off base with it? I will give it a shot this weekend to see how precise it is (if at all) but won't get film back for a week or so.

Any thoughts are very much appreciated.

Johnny

[el french]

If you have a lot of play in the dial, you won't be able to set it accurately until you determine how much backlash there is and if it's accurate when increasing the bellows draw or decreasing it (or neither).