EDIT:I changed the category for this deviation to Resources > Tutorials > Photography. I felt it was better placed here then in Photography > Misc.

This is a Pinhole I made for my Canon DSLR.

I used a body cap so I can thread it directly onto the camera and avoid the most possible dust. I found the center of the cap by measuring the widest diameter and drawing 3 lines across the center inside the cap. Then I drilled a small divit using a small pocket knife... I made this hole deeper using a small brad (a very small nail)... Once there was a dimple on the opposite side, I made the pinhole using... you guessed it, a pin.

I measured the opening using Photoshop... I know the "N" in Canon is 2 mm wide, so I measured the "N" and the diameter in photoshop, using a ration equation I came up with a diameter of roughly 0.46 mm. Using the equation for Fstop (Fstop = Focal length devided by aperture diameter)... I calculated that this pinhole is roughly f-109.

EDIT: After shooting about 100+ images with this, I found that even though the hole is less then 1 mm, when the sensor gets charged it sucks dust into the chamber like mad... SO, I took a trip down to my local camera shop, and asked for a lens filter that would fit over this thing to prevent dust from entering the hole when the sensor is charged during exposure. I expected to find a filter large enough to fit snugly over this body cap and glue it onto the outside...

Well the folks at the camera shop supprised me yet again. As it turns out the inside ring of this body cap holds a 46mm filter with metal ring perfectly... no need for glue. I purchased a 46mm Quantaray UV filter and pressed it (gently) inside the inner ring of the body cap and now... no dust (well there still dust in the chamber, but no new dust enters. My next purchase will be a sensor cleaning brush, one that electrostatically charges itself to suck dust off the sensor and out of the chamber).

(Ill post a picture of the inside(with Filter) as well shortly)