Timeline for What are the challenges of creating a pinhole camera with short focal length?
Current License: CC BY-SA 3.0
12 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Nov 13, 2013 at 10:31 | comment | added | Edgar Bonet | For maximum sharpness, you have to make a hole that is both small and circular. The edges of the images will suffer from both vignetting and reduced sharpness. I’ve made a 6×9 (really 56×84 mm) pinhole camera with 25.5 mm focal length. That’s about the shortest reasonable. Vignetting is strong but I can live with it. You could use a curved film surface to reduce the vignetting, at the expense of some distortion. | |
| Nov 7, 2013 at 15:04 | vote | accept | user2078515 | ||
| Nov 6, 2013 at 20:06 | comment | added | ysap | Interesting - I did not think about these effects. I think, however, that for ideal pinhole camera, with infinitesimal hole size, this should not be a problem (but other problems, like diffraction may arise). | |
| Nov 6, 2013 at 6:44 | history | tweeted | twitter.com/#!/StackPhotos/status/397977825770496000 | ||
| Nov 5, 2013 at 21:05 | comment | added | coneslayer | @ysap Pinhole cameras suffer from "natural vignetting" (the cos^4 law) no matter how thin the material is. You get two powers of cos(theta) from the inverse square law (as the OP points out), one power from the light illuminating a larger film area off-axis, and one power from the hole "looking" smaller off-axis. cartage.org.lb/en/themes/arts/photography/photproces/… | |
| Nov 5, 2013 at 19:07 | history | edited | user2078515 | CC BY-SA 3.0 |
added 70 characters in body
|
| Nov 5, 2013 at 19:07 | comment | added | ysap | The vignetting is not (directly) caused by the distance difference to the edge of the film, but due to the thickness of the punctured cover ("lens"). Indirectly, of course, having a big difference in the distance means that you have a large angle of view, which means that you need a thinner cover so extreme angled rays are not blocked by the hole sides. | |
| Nov 5, 2013 at 18:29 | answer | added | Caleb | timeline score: 3 | |
| Nov 5, 2013 at 17:39 | comment | added | DJClayworth | Technically a camera without a lens can't have a focal length. I'm not sure what the equivalent is for a pinhole camera though. | |
| Nov 5, 2013 at 15:56 | history | edited | user2078515 | CC BY-SA 3.0 |
deleted 3 characters in body
|
| Nov 5, 2013 at 14:51 | answer | added | AJ Henderson♦ | timeline score: 4 | |
| Nov 5, 2013 at 14:00 | history | asked | user2078515 | CC BY-SA 3.0 |