As Large As Life.
Some people will be familiar with "The Behemoth" - my home-built 20"x24" mammoth plate camera which I've demonstrated at a few workshops. The current spell of good weather has meant I've finally had the time and conditions to have a bit more of a play with it.
The lens is a 21" (533mm) f/10 Taylor Hobson Cooke from a process camera with enormous coverage. The bellows extend to about 32 inches (812mm) which allows a good range of focus but this means it won't focus closer than about 60 inches (1.5m). This is close enough for most things, especially at this scale but it would be interesting to be able to photograph things at life-size.
A bit of calculating (the principal lens formula: 1/V+1/U = 1/f is so useful in camera building!) shows that for a 21 inch lens I needed a bellows length (U) of 42 inches. - Actually for 1:1 magnification it's easy- just double the focal length). As the bellows wouldn't stretch further I built the Behemoth Close-Up Accessory - a 10 inch deep wooden box which clips to the back of the camera to extend it.
So to test it: The idea was always to make life-size head and shoulders portraits so I started with a self -portrait. - Always one to make things as difficult as possible for myself!
The depth of focus is tiny at f/10: - maybe an inch at best. I used by head clamp/rest to make my position the same every time and set up a rod on a stand with a paper flag as close to where my eye would be as I could. Focusing on this was just about possible.
The full set up:B&D Workmate bench is better than a tripod... |
The two plate cameras behind me are just to make an interesting background. The round mirror by my feet is adding a bit of reflected highlight into my eyes. The two sticks to my right are my focusing target and to operate the card flap over the lens I used as a shutter. (This idea I got from Sally Mann: It works beautifully!) Also visible is the metronome used for timing the exposures. 45 seconds at f/32 was the final exposure.
Here's my final picture for the day: I can't say it's particularly great: The chair I used made me 'slump' too far back and the camera should have been lower. My grumpy expression is mainly due to trying to keep still and with my eyes open for a long time on a bright day. Anyhow, it was meant as a test of technique and feasibility more than a piece of artistic expression.
Life-size self portrait. PR. August 2016 |
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