? Parallax and Simultaneous Pinhole Camera Exposures?

[Michael Heald]

Hello! I have an 8x10 pinhole box camera with a FL=12 inches. I've been toying with the idea of dividing the 8x10 film area into four 4x5 spaces, use dividers, and have four pinholes on the front of the box. I would then use filters to give LRBG exposures.

The trouble is registering the resultant four 4x5 negatives, since the negatives would be separated by 5 or 6 inches and parallax would come into play.

For a distant point at infinity, how close can an object be before parallax would cause the objects not to be able to be registered, given the diffusion circle of a pinhole camera?

Alternately, after digitally scanning the negatives, each RBG exposure can have numerous registrations on the Luminous negative for points that are different distances from the camera. Is there a way to subtract the unregistered parts at each registration, then sum th eregistered parts, so that the resultant negative would be completely registered on the L or Luminous negative?

Thank you and best regards.

Michael A. Heald

[Walter Calahan]

I wonder if Photoshop's Free Transform within Merge could eliminate the parallax problem so you don't have to worry about doing any calculations?

[Mark Woods]

Use the parallex and shoot 3D!

[Tracy Storer]

It's a neat idea, I've done in-camera separations in both pinhole and lensed cameras, and the idea of simultaneous seps is compelling, but just shooting 4x5 chrome and separating in the computer probably makes more sense.
Since you've already got the 8x10 pinhole, why not try it? It'll only take a couple shots to find your "too close to register" distance. It'll vary from shot to shot depending on the relative depths in your shot. (5"-6" is a pretty big inter-ocular distance)

[Jim Jones]

I wrestled with this problem in theory many years before digital imaging, and decided against experimenting with it. If the registration of the four images is perfect for an indinitely distant subject, I believe anything closer than several hundred feet will display parallax.

[Greg Lockrey]

Use the parallex and shoot 3D!

That's what I was going to say.

[Michael Heald]

Several hundred feet? That's a bit much, though with pinhole, it might have an interesting effect.

In Photoshop, would it be be possible to select a registration point and then mask the unregistered portions? Different registration points could be selected that correspond to different distances from the camera and the different registrations could be added in order to have the complete image.

At least, that was my second idea. With my limited understanding of PS, I may be way out in left field. Best regards.

Michael A. Heald

[Jim Jones]

Michael, it might be possible, but might also require much cleaning up of the background where the foreground areas are moved from. Your knowledge of PS may be extensive by the time you solve all the problems.