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Jimmy G
06-08-2009, 05:26 PM
Last winter i built this photo finish camera from a 120 folder that had been a PH cam in a previous incarnation. The frame is an ensign 12-20 6x6 folder to which I
* removed the folding door
* added a slit at 0.7mm width at the film gate - 2 razor blades mounted side by side (blackened to avoid flare)
* added a pentax K lens mount (at the correct distance from the film plane - focus is by scale so this is important)
* grafted on a pentax super ME power winder (the drive shaft was the hardest part)
* modified the DOF knob to be a rewind knob with spring load to allow load/unload
* modified chamber to take the 35mm cassette
* made a guide for the viewfinder to reflect 50mm lens filed of view

to detemine correct exposure the effective shutter speed needed to be calculated. This was done by measuring the film speed and dividing this by the slit width. The film speed i measured by timing how long it took for a metre length of film (marked with lines) to be driven through the camera - in this case it is 72mm per sec so the effective shutter speed is 1/100 sec. Exposure is varied by aperature only as the winder only has this one speed.

Examples pics posted below with pics of camera. It's a fun camera to use and i am only really getting to grips with it after 4 or 5 rolls. Attached files http://f295.f295.org/uploads/slit_3017.jpg (http://f295.f295.org/uploads/slit_3017.jpg)

Jimmy G
06-08-2009, 05:44 PM
Note the punched hole in the film for a good grip in the 120 spool which pulls it along.

Some pics.. sorry about the links, i'm having a real hard time uploading the pics, my connection is very slow this evening.

http://www.flickr.com/photos/limerick37/3329553130/in/set-72157606229836139/

http://www.flickr.com/photos/limerick37/3463902830/in/set-72157606229836139/

http://www.flickr.com/photos/limerick37/3463905820/in/set-72157606229836139/

http://www.flickr.com/photos/limerick37/3418517667/in/set-72157606229836139/

pob
06-08-2009, 07:05 PM
I remember the black and white ones. I hadn't seen the other. Excellent!

renon
06-09-2009, 03:11 AM
Hi Mr. Jimmy Frankenstein, very nice and interesting pictures. An excellent camera hack. Pinholers are the masters of recycling. :)

earlj
06-11-2009, 06:39 PM
These images are wonderful and amazin, Jimmy. My hat's off your ingenuity and rubber determination.

McFortner
06-15-2009, 03:44 PM
Ooohhh, I want one. I wish I was that mechanically talented. I barely know enough to make a pinhole camera from a cheap 35mm camera. Yours looks like it could have been made that way from the factory! And it takes great photos to boot.

Michael

antbiker
06-16-2009, 08:34 AM
Absolutely brilliant pictures Jimmy. Very well done indeed.
I still can't get my head around how the subject gets frozen & the background is streaked - help me out someone!

jzall
06-17-2009, 01:31 AM
I still can't get my head around how the subject gets frozen & the background is streaked - help me out someone!
If I understand it correctly, the film is moving during the exposure, similar to panning the camera itself to follow the subject.

Even so, the results are really amazing!