Pinspeck photography

[BetterSense]

Wikipedia says a pinspeck camera is like a pinhole camera, only that uses the opposite of a pinhole, that is, a pinspeck, to give negative images.

Is it true? I don't see how it could possibly work.

 

[Nitai108]

With a pinspeck camera you obtain a positive image (on a negative film or paper). Take a look here: http://www.wesjones.com/pinhole.htm Figure 7 and 8.
It's quite an interesting and unusual technique, I'll probably try it sometime.

 

[Nitai108]

"Fig. 11. Pinspeck camera. The opaque disk in the center of the glare stop casts
a shadow of each bright point in the object This results in a weak, negative image."

From: http://www.cartage.org.lb/en/themes/Arts/photography/photproces/pinholephot/pinholcam/pinholecam.htm

The negative image on a negative support results in a positive image, the opposite of what the pinhole camera does.

 

[Joe VanCleave]

Here is a post I made several years ago on F295 about a "pin-head" camera using a tiny front-surfaced mirror in place of a pinhole. It doesn't produce a tonally reversed image, just a reflection version of a pinhole camera. I'm not sure if diffraction effects are any better or worse, considering there's no "edge" of a hole for light to refract around.

Here are three images made with this camera. The fuzziness around the edges is the black craft felt, used to prevent forward scattered light fogging, getting in the way of the image path. A revised design was "in the works" but I haven't gotten around to it yet. Scans of paper negatives.

~Joe

 

[BetterSense]

Thank you very much for the link about pinhead photography. It's a fascinating design and I have no trouble believing it works. I still do not believe in pinspeck photography though and have yet to see a working camera. My friend and I both have several different lines of reasoning as to why it wouldn't work, and the topic comes up every now and again.

 

[DarkroomExperimente]

oh that's wonderful...had heard of the "pinhead" ( although not by that name ), but never saw an example

I have a few front surface mirrors rescued from polaroid cameras...now I need to try it

I assume you could also mask the unwanted portions of the mirror with paint or something also instead of trying to make a tiny mirror


never saw any actual photos taken with a pinspeck either

now I need to make these rascals...wow

 

[Joe VanCleave]

What I did to make the pin head mirror is to cut a small (~1/4" square) piece from a larger front-surfaced mirror using a glass cutter, then paint all sides with india ink, leaving as small of an unpainted, circular spot as possible in the middle of the front side.

I suppose a person could get a metal wire, like solid core aluminum and, clamped inside a special fixture, could polish the end to a mirror finish.

My prototype uses a 90 degree reflection angle for the center of the field of view; however, it can be seen from the diagram on the F295 link that one side hits the mirror at a steeper angle, and the other at a more grazing angle. Depending on the quality of the mirror, it's possible that the side of the image made principally by the grazing angle could experience a loss of contrast and detail, due to scattering of light off an irregular mirror surface at a grazing angle.

This design also limits itself to fairly normal and telephoto angles of view, the mirror and baffles limiting how wide a field of view that's possible while still not fogging the film plane from stray light.

As I indicated in the link, the next model will be a more cubical box, with a diagonal partition running from one corner to the other, the middle of which has a small aperture for mounting the mirror and permitting the light to enter the dark half from the light half, the opening just big enough to encompass the necessary field of view. Since the mirror is mounted on the back edge of this opening, the opening itself doesn't have to be that big, a fraction of an inch.

~Joe