
Posted: Wed May 30, 2007 11:45 am
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I will have to build a new lensboard as well, as the old one (made of plywood, not sure if this is the original material) is coming apart. Lens is quite heavy. So I thought to use wether aluminium or POM or PA6 plastic (sacrilege, if I don´t find a piece of nice hardwood) for this. Actual size is 84 x 84 mm = 3-5/8" and 5,5 mm = 7/32" thick. I can take the dimensions and shape from this one, but would prefer to have a tech drawing of the original one. Anyone out there can help ?
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This is going to get interesting:
According to A history of Graflex by Paine the Telescopic Revolving Back Auto Graflex 1912-1914 , a 4 x 5, has a 4x4 lens board. The Telescopic (Tele) Revolving Back Graflex 1915-1923 in 4x5 should have a 4x4 lens board but it is noted that 1918 had a 3 3/4 x 3 3/4 lens board.
I have a Series B Graflex that when I requested a date for it, it turned up it was at the top of a block of numbers assigned to the Tele Graflex starting production in early 1922. (The Series B changed design and is offically listed as starting in 1923. There are Tele's with serial numbers in 1926, 3 years after it was discontinued.) Did Graflex make different front standards or at least change the lens board opening in the front standard from year to year?
The 4x5 Series B (dba Tele Graflex rebaged) that I have has a lens board stamped B on the back and measures as follows:
Top to Bottom=3.741 inches/95.12mm
Left to Right=3.729 inches/94.72mm
Thickness= .25 inches/6.37mm
Front=flat
Rear: Edges Rabeted as follows:
Left and right: inward from outisde edge= .141 inches/3.58mm
Bottom: inward form outer edge=.254 inches/6.45mm
Top: inward from outer edge=.254 inches/6.45mm; approximate 45 degree bevel rear to front of board that leaves the top edge .092 inches/2.34mm thick and goes .118 inches/3mm inward from top edge (roughly 1/2 of the width of the rabet).
Rabet depth=.112 inches/2.85mm.
You can measure your camera's lens board opening left to right/top to bottom to get the basic measurement. Next measure the depth of the slot at the bottom and add that to the top to bottom measurement. Now measure the top edge to tension spring when it is in the uncompressed state and add that to the top to bottom measurement. The alternative will be to measure from the base of the lens board slot at the bottom to the edge of the spring uncompressed for the top to bottom measurement.
Measure the top to bottom and left to right of the front standard immediately behind the lens board slot. This will be the size of the back of the lens board once it is rabeted. The rabet forms the light trap. Bevel the top edge so that the board will go in at a 45 degree angle and rotate inward into position to slide into the slot. If you make it a little large it can be sanded/filed down to fit but if a little small it cannot be enlarged.
Material suggestions are Baltic birch plywood, Mahogany, black ABS Plastic, and black Acrylic work well for lens boards. Any material that will not warp, at least 1/4 inch thick and is rigid can be used.
Charles