Thread: Pin Hole VS Glass Lens View Single Post
#2
June 12th, 2006, 01:17 PM
 Doug Kerr Guest (Moderated, Given real name in post) Posts: n/a
Some optical proerties of a pinhole camera

Quote:
 Originally Posted by Will Thompson Greetings to All, a nagging question of some importance to start a heated discussion. (better than the chicken or the egg question) Pin Hole VS Glass Lens, Similarities & Differences in depth of field, depth of focus, sharpness, f stop, and differences in distance to film plane/sensor. What are they?
Nag, nag, nag.

Here are a few considerations:

Depth of field, depth of focus: These are not defined, since there is no concept of focus.

f/stop: As a first approximation, the exposure implication of a pinhole camera is the same as a camera with a lens whose f/number is the ratio of (a) the distance from the pinhole to the sensor to (b)the diameter of the pinhole.

Field of view: Field of view actually works just the same as on a camera with a lens (glass or plastic): it is determined by the dimensions of the format and the distance from the exit pupil to the sensor. (In a camera with a lens, there is a small complication if the pupils are not collocated with the nodal points, but I'll ignore that for now.)

Of course in a camera with a lens, we tend to think that the second factor is the focal length. But that's only because, with the camera focused at infinity, the distance from the exit pupil to the sensor (again, ignoring pupil displacement) is the same as the focal length. It is the distance that actually does it in either case.

Magnfication: The magnfication of a pinhole camera (for an object at any distance) is the ratio of (a)the distance from the pinhole to the sensor to (b)the distance from the pinhole to the object.

Sharpness: Sharpness? Sharpness? Too dull a pin will not make a nice hole.

Difference in the distance to the sensor: That could be the same or different, depending on what you make them. Some implications of the distance in the case of the pinhole camera are mentioned above.

The chicken/egg matter: An embryologist is a scientist who thinks that a chicken is just an egg's tool for making another egg.