Pinhole-calculations

[europanorama]

I am reflecting about which camera is matching which pinhole.
here on aupremierplan-site i have seen this Pinhole diameter/FLs-table

on his 4x5 he is using 0.2 leading to 35mm and f175
whereas 18° has also a 0.3 pinhole leading to 40mm and f200.
does this mean filmplate to pinhole is deciding which pinhole-range is best?
aupremierplan telling us that best is as thin as possible.
if only one could exchange pinholes by zoneplate or zonesieve on the RSS 4x5.
18° has pinholes with shutter/cable-release-connector. would like to attach to Polaroid MP4 or one of the two 18° 4x5 cams, one with movable bellows for 47-150 -lenses, the other for 58 and 65mm fixfocus. or pinhole.

 

[kier]

Hi - yes, the distance from the film plane to the pinhole is what determines the pinhole size. There are optimum sizes for every distance, and that's what he's referencing in the table.

"best is as thin as possible" - this is referring to the thickness of the material that the pinhole is made in. You want the thinnest piece of metal possible to reduce difraction of the projected pinhole on the film plane.

If you want to be able to adjust pinhole sizes, zoneplates, focal lengths, and be able to use a polaroid back, you might want to look at the Zero Image 4x5:
http://www.zeroimage.com/Pinhole_Camera_45_2015.html

Both the Zero Image and the Reality so Subtle are fantastic cameras. They both produce absolutely top notch imagery. But the Zero Image has the adjustments that you might be looking for.

 

[DWThomas]

Another reason for "as thin as possible" is that the as we look at the light rays away from the central axis of the camera, the pinhole becomes an ellipse which reduces the effective opening and therefore, exposure. When the hole is in a thicker plate the effects off-axis are much more rapid resulting in noticeable fall-off toward the edges, and can even vignette as the hole through a very thick plate behaves more like a cylinder.

 

[kier]

Another reason for "as thin as possible" is that the as we look at the light rays away from the central axis of the camera, the pinhole becomes an ellipse which reduces the effective opening and therefore, exposure. When the hole is in a thicker plate the effects off-axis are much more rapid resulting in noticeable fall-off toward the edges, and can even vignette as the hole through a very thick plate behaves more like a cylinder.

That's a more accurate description of the effect I was referring to

 

[TheToadMen]

The pinhole size and distance to the lens determine the f-number (aperture) of the camera.
The size of the negative and the distance between the pinhole and the negative determine the angle of view of the camera.

There is a simple Windows program to help you to calculate this (and more): http://www.pinhole.cz/en/pinholedesigner/
More info about the working of pinhole cameras can be found here: http://www.pinhole.cz/en/pinholecameras/

 

[poppaneedsanap]

wow!! had never seen the Zeroimage stuff until now..
very cool