[davewaldo]

Thanks mate,

Having done this a bit at uni I might just add something. Rather than using the needle to push all the way through to make the hole I found that you could get a far better quality hole by just making a dent with the needle, then using fine sand paper from the other side sand the dent until a hole is made. By doing it this way you have far more control over the size of the hole and also usually this technique gives a more round hole. It also makes the tin as thin as possible at the hole edge (important for minimising diffraction)

There are also ratios of hole diameter to sensor/film size which can be found on the net. A hole too small and you will get too much diffraction, too big and it will be softer than what is possible. I used a fine ruler and a kiddie microscope to check size.

But this all depends on how serious you want to get...

Enjoy,

Dave