Many Thanks Kerry. And (ahem) you said.. "metric" ;-);-) ?? My understanding was that in the US, only officials at the National Bureau of Standards used metric scales ;-);-)
And not kidding : we are now all set to virtually build our next "dreamed" Arca Swiss camera. Keep us informed about your 4"x20" project.
Emmanuel, Maybe it has something to do with using the English language that has us tied to wondering how many links to a furlong or gills to a hogshead.
And to think that Thomas Jefferson advocated a decimal system before there was a metric system.
Does anybody know (or care) what king's foot was twelve inches long?
I have a slide caliper which almost measures current inches, but not quite. It dates from the period in which Munich measurements were not the same as Heidelberg dimensions.
At Photokina 2004 Arca Swiss showed me a new type of front/rare frames of wich the weight was reduced by taking off metal out off the frames. You will win about 600 grams for a whole 4x5" camera. They also have a new type of lensboard; one with a bajonet. You have one lensplate with a round hole (with bajonet) and need only small round plates for the lenses.
Bart. Good news for Arca-philes. The frames you are referring to are the new 140mm standards identical to the rear misura standard. Downsizing from 171 to 140 is a major improvement in compactness already visible in the misura. So we can say now that those who insist on having full rear tilts will simply use the new 140 mm frames on their function supports with new smaller square bellows, 140 mm square front and rear instead of 171mm. The mixed 6x9-4"x5" approach in the new 140 mm F-line models is simply a front 6x9 and a rear 140mm 4"x5" frame connected by the misura leather bellows. New 140 mm frames will be (or already are) available in "metric" flavour as well.
The bayonet mount you are referring to, is based on a simple principle that I had seen implemented for quick-fit of threaded lens hoods. It is a conventional thread mount like the good old M42x1 for 35 mm lenses except that the diameter is bigger (can accommodate a #3 shutter) and with three complementary lobes ~60 degrees wide @ 120 degrees milled on both parts. You just push boths parts taking advantage of the milled lobes and you screw-in and lock by turning sligthly less than 60 degrees. Of course you can use conventional square boards if you wish, it is up to you : either the 140 mm threaded lens board with the bayonet mount, or conventional boards one for each lens.
Does Arca also have recessed boards with bajonet? They also have lensboards 110x110 for a 6x9 frontstandard. Do they have also a bajonetsystem for the 110-lensboards?
Does anybody know (or care) what king's foot was twelve inches long?
The unit of measure 'foot' was not actually derived from a king's foot... that is a common misconception. Almost every culture has used the human foot as a unit of measurement. The natural foot (pes naturalis in Latin), an ancient unit based on the length of actual feet, is about 25 centimeters (9.8 inches). This unit was replaced in early civilizations of the Middle East by a longer foot, roughly 30 centimeters or the size of the modern unit, because this longer length was conveniently expressed in terms of other natural units:
1 foot = 3 hands = 4 palms = 12 inches (thumb widths) = 16 digits (finger widths)
This unit was used in both Greece and Rome; the Greek foot is estimated at 30.8 centimeters (12.1 inches) and the Roman foot at 29.6 centimeters (11.7 inches). In northern Europe, however, there was a competing unit known in Latin as the pes manualis or manual foot. This unit was equal to 2 shaftments, and it was measured "by hand," grasping a rod with both hands, thumbs extended and touching. The manual foot is estimated at 33.3 centimeters (13.1 inches).
In England, the Roman foot was replaced after the fall of Rome by the natural foot and the Saxon shaftment (16.5 centimeters). The modern foot (1/3 yard or about 30.5 centimeters) did not appear until after the Norman conquest of 1066. It may be an innovation of Henry I, who reigned from 1100 to 1135. Later in the 1100s a foot of modern length, the "foot of St. Paul's," was inscribed on the base of a column of St. Paul's Church in London, so that everyone could see the length of this new foot. From 1300, at least, to the present day there appears be little or no change in the length of the foot.
Late in the nineteenth century, after both Britain and the U.S. signed the Treaty of the Meter, the foot was officially defined in terms of the new metric standards. In the U.S., the Metric Act of 1866 defined the foot to equal exactly 1200/3937 meter, or about 30.48006096 centimeters. This unit, still used for geodetic surveying in the United States, is now called the survey foot. In 1959, the U.S. National Bureau of Standards redefined the foot to equal exactly 30.48 centimeters (about 0.999998 survey foot). This definition was also adopted in Britain by the Weights and Measures Act of 1963, so the foot of 30.48 centimeters is now called the international foot.
---Scott
www.srosenberg.com
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