Posted: July 16, 2003, 6:09 am
I was out one day with an 8x10 holder looking for a box that might fit. I found the box at the local craft store that was longer than the holder and just a little narrower. I bought it for $6 and took it home and carefully measured where the holders groove would be if the edge of the box lined up with the holder's outside lip.
Then used a ruler to see where the opening of the holder where the film would be exposed. I cut out the hole and proceeded to use a Dremel sanding drum on the groove line, matching up the holder to the box several times until the holder sat flush over the box.
The holder sat out from the front and back of the box by about an eighth of an inch, I took a 1/2 x 1/2 x 24 piece of wood and cut it to fit the length of the box. I then carefully attached these with 3 brass wood screws. Then fitting the holder to the back again, I had to extend the groove partway into these wood strips. Putting the holder in place, I used 3/8 x 3/8 wood to "fence it in" on three sides. The smaller was used so that the edge of the film holder could be pushed by a pressure plate.
Put in a "T-hole" for 1/4-20 thread for vertical mounting on a tripod. This will let in light, so after attaching it with 3 "0" brass screws, I put masking tape over the hole and mixed a batch of J B Weld epoxy to cover it well. I then spray painted the inside dark blue (did't have black) twice. After the second coat and while still wet I closed the box effectively painting it shut the first time.
Then I brush painted the outside sports car red, for zero to full exposure in 10 seconds, painting it shut for the second time. And that not being enough, I spread J B Weld on the inside where the top and bottom meet.
Drilled a hole for the pinhole. Lightly glued it to the front so that I could epoxy it good from the inside.
Used India ink on the shelves that receive the holder. Epoxied on a step up ring for 52mm filters and a snap on cap for a shutter.
Now the back was hard. I made several attempts at using spring piano wire and a board for a pressure plate but failed. In frustration, I used two pieces of oak with hinges and hasps. But hey, it works!
The effective focal length is 160mm. A laser pinhole of .5mm gives it an effective f/stop of 320.
Field test. Efke PL25 10 second exposure 4 1/2 minutes in D-76.
Small piece of an 8x10 neg (~3 x ~5) of the Louisianna Monument on the Gettysburg Battlefield. Taken about 1 1/2 hours after sunrise with a yellow filter. Efke PL25 exposed for 45 seconds and developed in D-76 straight at 4.5 minutes.
Finished at last. Put in another "T-hole" for mounting horizontally and then painted the holder clamps.
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