Camera Obscura

[nrois02]

Hey all, I havent posted on here in a while so Im sorry if this is in the wrong spot. I am going to be trying to do a room size camera obscura and i have looked on some different websites to do it and some say to build a lens and some say just to cut a hole out. I was wondering if anyone on here has tried and could spread some light on what they did and how they went about making the hole and then if it was a really ong exposure if they made a way out of the room and how they did that too. sorry if this is vauge but any questions or answers would be great!

_Austin

 

[KmH]

It seems you are describing a large pinhole camera, not a camera obscura.

Slideshow: Camera Van Brakes for Close-Ups

Camera obscura - Wikipedia, the free encyclopedia

http://www.thephotoforum.com/forum/...um-photo-gallery/151262-6-month-exposure.html

 

[white]

Just black out the room and cut a hole in the material. The smaller the hole, the sharper the image.

How-to

 

[Garbz]

white, not quite right. The smaller the hole the large the depth of field but you end up with diffraction problems, as well as issues with making the perfect hole with no burrs. There is an optimum pinhole size for a given focal length. It and a lot of other build relevant maths are on the wikipedia page: https://secure.wikimedia.org/wikipedia/en/wiki/Pinhole_camera
Or a simple close approximation is [holesize in mm] = 1/25 * sqrt([focal length in mm])

There's some more theory to guide your construction here for a pinhole: Theory

For instance a 4m focal length (across the room) you may want a 3mm hole.

 

[nrois02]

awesome guys! thanks a lot! ill post pics when i have tried it out!