A Pinhole camera - (in need of help)

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bhs128
Posts: 3
Joined: Sun Nov 07, 2010 8:14 pm
Location: North Metro
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Re: A Pinhole camera - (in need of help)

Postby bhs128 » Tue Nov 09, 2010 11:59 am

Thanks for all the comments- all good questions. I plan on bringing what I have to the meetup tomorrow, so we can talk it over too.

The paper I'm using is ILFORD B&W: http://www.ilfordphoto.com/Webfiles/2006130200232336.pdf

The moisture issue crossed my mind as well-- I have extra silca gel packets laying around, perhaps I could secure one or two of them inside (in such a way as to not block the light path).

The expansion/contraction thing concerns me - perhaps it is reason enough to switch to a 7/8" cavity to allow for some more wiggle room. I was planning on using black caulk or silicon rubber to adhere the pinhole in position, which may help in its flexibility.

I made a sketchup model of the camera (and pinhole insert), feel free to take a look: http://www.bhs128.com/projects/pinhole/camera.skp

Image

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metis
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Joined: Wed Jan 14, 2009 10:06 am
Location: NE Minneapolis
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Re: A Pinhole camera - (in need of help)

Postby metis » Wed Nov 10, 2010 9:04 am

ok i can see that working pretty well.

the math is out there for sussing out expansion and contraction for the diameter of the tube at various temps, i'd find the min and max and route out the notch a hundredth or two wider. remember wind chill doesn't affect metal, but solar gain does. the CNC router would be ideal for putting that in as i don't believe we've a circle template for the router.

roofing sealant is not a bad choice, but it offgasses some fun things that might effect your paper or your better half. 100% silicone should hold up just fine though, and only offgasses acetic acid (vinegar) as it's curing. you'll want "food safe" or aquarium caulk. i believe only GE manufactures it anymore, but it's sold under GE, DAP and several spendy brands as aquarium sealant.

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otto_pjm
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Joined: Tue Apr 06, 2010 10:12 pm

Re: A Pinhole camera - (in need of help)

Postby otto_pjm » Sat Nov 13, 2010 10:59 pm

I know we couldn't get enough height on the CNC, but I do have forstner bits, I can bring down if that helps. I think some of that nice thick MDF cut at 45 degree angles would make a good v-block base for the drill press.


Pete


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