# An easy DIY lightproof drain for a pinhole camera? **URL:** \ **Category:** Factual Questions\ **Created:** [December 17, 2018, 10:33pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292 "2018-12-17T22:33:59Z")\ **Posts on this page:** 9\ **Page:** 2
**Author:** ![brossa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brossa/32/3040_2.png) [@brossa](https://boards.straightdope.com/u/brossa)\ **Post date:** [July 10, 2019, 2:33pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/21 "2019-07-10T14:33:15Z")
[Example images here,](https://hosting.photobucket.com/images/n291/brossa/0/9f8389a9-7c61-47f1-becb-9f7693d6622a-original.jpg?width=1920&height=1080&fit=bounds) [here,](https://hosting.photobucket.com/images/n291/brossa/0/602b6031-bcae-48a9-bb9c-e0d6f8d62f1f-original.jpg?width=1920&height=1080&fit=bounds) and [here](https://hosting.photobucket.com/images/n291/brossa/0/a033b838-d0ed-479b-bfc2-42c876d0520e-original.jpg?width=1920&height=1080&fit=bounds), showing 6 months of solar tracks from winter solstice to summer solstice. I will also make sure not to leave fingerprints on the photo paper next time. ---
**Author:** ![beowulff](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/beowulff/32/542_2.png) [@beowulff](https://boards.straightdope.com/u/beowulff)\ **Post date:** [July 10, 2019, 2:54pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/22 "2019-07-10T14:54:06Z")
> [@brossa](#): > > [Example images here,](https://hosting.photobucket.com/images/n291/brossa/0/9f8389a9-7c61-47f1-becb-9f7693d6622a-original.jpg?width=1920&height=1080&fit=bounds) [here,](https://hosting.photobucket.com/images/n291/brossa/0/602b6031-bcae-48a9-bb9c-e0d6f8d62f1f-original.jpg?width=1920&height=1080&fit=bounds) and [here](https://hosting.photobucket.com/images/n291/brossa/0/a033b838-d0ed-479b-bfc2-42c876d0520e-original.jpg?width=1920&height=1080&fit=bounds), showing 6 months of solar tracks from winter solstice to summer solstice. > > I will also make sure not to leave fingerprints on the photo paper next time. Pretty cool! ---
**Author:** ![CalMeacham](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/calmeacham/32/35_2.png) [@CalMeacham](https://boards.straightdope.com/u/CalMeacham)\ **Post date:** [July 10, 2019, 3:32pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/23 "2019-07-10T15:32:57Z")
> [@brossa](#): > > [Example images here,](https://hosting.photobucket.com/images/n291/brossa/0/9f8389a9-7c61-47f1-becb-9f7693d6622a-original.jpg?width=1920&height=1080&fit=bounds) [here,](https://hosting.photobucket.com/images/n291/brossa/0/602b6031-bcae-48a9-bb9c-e0d6f8d62f1f-original.jpg?width=1920&height=1080&fit=bounds) and [here](https://hosting.photobucket.com/images/n291/brossa/0/a033b838-d0ed-479b-bfc2-42c876d0520e-original.jpg?width=1920&height=1080&fit=bounds), showing 6 months of solar tracks from winter solstice to summer solstice. > > I will also make sure not to leave fingerprints on the photo paper next time. Extremely neat ---
**Author:** ![Melbourne](https://avatars.discourse-cdn.com/v4/letter/m/b5e925/32.png) [@Melbourne](https://boards.straightdope.com/u/Melbourne)\ **Post date:** [July 11, 2019, 9:00am UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/24 "2019-07-11T09:00:37Z")
Dude, that is cool. ---
**Author:** ![am77494](https://avatars.discourse-cdn.com/v4/letter/a/d2c977/32.png) [@am77494](https://boards.straightdope.com/u/am77494)\ **Post date:** [July 11, 2019, 12:44pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/25 "2019-07-11T12:44:33Z")
> [@brossa](#): > > [Example images here,](https://hosting.photobucket.com/images/n291/brossa/0/9f8389a9-7c61-47f1-becb-9f7693d6622a-original.jpg?width=1920&height=1080&fit=bounds) [here,](https://hosting.photobucket.com/images/n291/brossa/0/602b6031-bcae-48a9-bb9c-e0d6f8d62f1f-original.jpg?width=1920&height=1080&fit=bounds) and [here](https://hosting.photobucket.com/images/n291/brossa/0/a033b838-d0ed-479b-bfc2-42c876d0520e-original.jpg?width=1920&height=1080&fit=bounds), showing 6 months of solar tracks from winter solstice to summer solstice. > > I will also make sure not to leave fingerprints on the photo paper next time. Wow - fascinating. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 11, 2019, 3:39pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/26 "2019-07-11T15:39:32Z")
The salt noise interests me. My guess is that those are from cosmic rays. I’m also curious about the blue smear in the last one, but I don’t have any hypothesis for that one. ---
**Author:** ![mixdenny](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/mixdenny/32/2962_2.png) [@mixdenny](https://boards.straightdope.com/u/mixdenny)\ **Post date:** [July 11, 2019, 5:04pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/27 "2019-07-11T17:04:51Z")
Nice. What is the ASA rating for the film used? Dennis ---
**Author:** ![brossa](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/brossa/32/3040_2.png) [@brossa](https://boards.straightdope.com/u/brossa)\ **Post date:** [July 11, 2019, 9:08pm UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/28 "2019-07-11T21:08:50Z")
> [@Chronos](#): > > The salt noise interests me. My guess is that those are from cosmic rays. > > I’m also curious about the blue smear in the last one, but I don’t have any hypothesis for that one. The salt noise is artifactual, and not present in the image. It’s from dust on the photo paper/scanner. The image is captured on B&W photo paper, not film. The naked-eye image is all pinkish browns and blue-grays on white, and looks like [this](https://hosting.photobucket.com/images/n291/brossa/0/0c9c3ea7-f46e-4268-a976-246035a39c58-original.png?width=1920&height=1080&fit=bounds) (this is oriented the same way that it comes out of the camera). The paper must be removed from the camera in the dark and then scanned. Cutting open the camera (spray painted black inside) to get the paper out introduces some dark dust, as does tossing them in a folder and then not being fastidious about the scanner bed. The image linked in this post is a second scan of that image, with more care taken to blow the dust off. Scanning exposes the paper to more light, so it darkens a bit each time. If the papers aren’t kept away from light, they eventually get uniformly reddish gray and the images are lost. I don’t know if it’s possible to fix the images chemically, but I don’t have any darkroom chemicals anyway. The scanned image is then flipped (vertically and horizontally) and color-inverted to give the final result, like [this.](https://hosting.photobucket.com/images/n291/brossa/0/aecc65cc-d2e0-4640-a426-7c06bb26b960-original.jpg?width=1920&height=1080&fit=bounds) Black specks on the original scan become white specks in the final image. This is a re-do of the ‘blue streak’ image with less dust; as a second scan of the same paper the colors are different. The photochemistry of why the black and white photo paper has colors at all is beyond me. Two of the images were more classically black-and-white, I think because the pinholes were smaller and less light got into the cameras. As for the black fingerprints, I think that the emulsion was pulled off or poisoned there, so those spots stayed white/unexposed, which gives black spots on the final image. The blue streak may be the only actual bit of water intrusion seen in this run of eight cameras. On the actual photo paper, it’s a reddish streak centered on a speck of something on the emulsion (as seen above). Because of the geometry of the camera, the tail is actually following gravity. I think a drop of water got into the camera and ran downward, staining the paper or affecting the chemistry somehow. As a further aside, [this image](https://hosting.photobucket.com/images/n291/brossa/0/9f8389a9-7c61-47f1-becb-9f7693d6622a-original.jpg?width=1920&height=1080&fit=bounds) is of a driveway emptying onto a state highway. I thought that 6 months of nighttime car headlights might show up, but apparently they aren’t bright and/or slow moving enough to register. > [@mixdenny](#): > > Nice. What is the ASA rating for the film used? It’s not film, it’s Ilford MGIV RC Deluxe 5x7" B&W photo paper, pearl finish. It never gets developed. I see that I said 4x6" in a previous post, but that was incorrect. A good starting point for this sort of pinhole photography is the [Solargraphy](http://www.solargraphy.com/index.php?option=com_content&task=view&id=16&Itemid=18) site of Tarja Trygg. ---
**Author:** ![Chronos](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/chronos/32/134_2.png) [@Chronos](https://boards.straightdope.com/u/Chronos)\ **Post date:** [July 12, 2019, 1:21am UTC](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292/29 "2019-07-12T01:21:51Z")
> [@](#): > > I don’t know if it’s possible to fix the images chemically, but I don’t have any darkroom chemicals anyway. Actually, you might. I don’t know what chemistry your photo-paper uses, but some of the older photopigments are fixed using acetic acid. More concentrated stuff probably works better, but you just might be able to fix the images you have by soaking them in vinegar. [Previous page](https://boards.straightdope.com/t/an-easy-diy-lightproof-drain-for-a-pinhole-camera/826292.md?page=1)