Dear World,

I'm trying to get my head around the following, any clarification would be greatly appreciated!

- I've turned a room into a Camera Obscura, and I'm trying to use it to expose paper negatives (standard Ilford RC paper).
Is there anyway I can accurately calculate the exposure with a light meter standing inside the Camera Obscura?

I typically rate my paper at ISO 6, then shoot wide open. My lens on the Camera Obscura is f9, however if already standing inside the camera, I'm assuming the aperture on the light meter is irrelevant?

So a working example would be as follows;
- Set light meter to ISO 6, f1.0
- take reading at film plane within Camera Obscura
- expose for indicated time

Am I on the right track??