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Turner-Reich 6.8 Series II NO. 2 Missing Part
I have a Grundlach-Manhattan Turner-Reich 6.8 Series II NO. 2 mounted in an Ilex shutter that I want to sell.
It is missing the f stop settings. Looking for a replacement 6.8 – 32 12 - 45 14 - 64 Bill |
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Turner-Reich 6.8 Series II NO. 2 Missing Part
"BillyBobby" wrote in message ... I have a Grundlach-Manhattan Turner-Reich 6.8 Series II NO. 2 mounted in an Ilex shutter that I want to sell. It is missing the f stop settings. Looking for a replacement 6.8 – 32 12 - 45 14 - 64 Bill -- BillyBobby You may have to have a new plate made and engraved. Its easy to calibrate the iris for the stop number. You can assume the marked focal lengths are near enough although the actual focal length of production lenses varies a bit from the "nominal" length. When the single cells are used on the back of the shutter or barrel the effective size of the entrance pupil is the physical size of the iris. When the lens is combined so that the iris is seen through the front lens you must measure the size of the entrance pupil, which is simply the image of the iris as seen through the lens. The first step is to autocollimate the lens to find the exact infinity focus. This is done easily by mounting the lens on a view camera. You can get an accurate enough measurement using the ground glass. Set a flat mirror against the front of the lens. Use a penlight flashlight or single LED against the ground glass, not quite at the center. The mirror will reflect an image of the light back to the ground glass. Focus it as sharply as possible. The lens is now focused exactly at infinity. Now, using the same small light against the ground glass place a translucent screen over the front of the lens. A bit of ground glass is ideal but paper works fine. You will now see a circle of light projected through the lens. The diameter of this circle is the diameter of the entrance pupil and the f/stop is the focal length of the lens devided by the diameter of this circle. To make a stop plate mount a piece of thick paper or card stock in place of the original plate. If you can mark it with arcs matching the stop pointer. You can probably use the stop pointer itself as a guide. Now, adjust the iris for the f/stop numbers you want and mark them on the card. Shops that do engraving can make a new stop plate based on this card. -- Richard Knoppow Los Angeles WB6KBL |
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