How to make a quality pinhole for: 110, 35mm, 120 film and digital.- Video here
A sharp pinhole image requires a hole made in metal (rather than through card or plastic).
If you follow the simple steps below you will be able to create some of the sharpest pinholes photographs around. You will need:
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Can opener - scissors
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An aluminium drink can
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A small needle file (an unwanted nail file will do)
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1200 grit emery paper
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A magnifying glass (inverted binoculars or camera lens)
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A clear ruler Needle or sharp map pin (Not a drawing pin)
The traditional method, (mentioned in many a pinhole book), makes use of brass shim being hammered onto a small ball bearing. Personally, (although a great advocate of hammering everything in sight) this is tricky and could dissuade people as 'brass shim' is something my corner shop doesn't sell!. It does however sell 'aluminum shim' in the form of cans of drink, which luckily need to be emptied (suffering for our art!) before making use of the wonders of aluminum.
Ensure the can is aluminum by checking it is non magnetic against a magnet in the fridge door. If it is magnetic it is steel (very hard and sharp) and you will need to buy a different make of drink till you find one that isn't. With applied carelessness this can take several attempts!
Empty the can, wash it out, and open it up using a pair of scissors cut down the length of the can and cut off the base. Uncurl the metal flat on the edge of a table.
Empty the can, wash it out, and open it up using a pair of scissors cut down the length of the can and cut off the base. Uncurl the metal flat on the edge of a table.
Choose an area away from the edge of the sheet of metal.
Using a small file remove the paint off the painted side of the can.
Turn the can over and, at the same area, file off the other side.
The thickness of the metal viewed edge on should then be like this:
Get a very sharp pin. (Most 'dressmaking' pins are fine).
With your middle finger moving behind the aluminium, begin gently drilling the pin into the thinned down metal.
Keep 'drilling' until you feel a slight scratching on your finger (not 'into' your finger!) then remove the pin.
Only the very point of the pin should puncture the metal.
Get your 1200 grit (ultra fine) emery paper, (ok even my corner shop doesn't sell this stuff but the place you bought your hammer from will have some).
Use the emery paper in a circular motion to sand the rough bump left by the pin.
The hole will probably get filled up with gunge so flick the hole and hold it up to the light to check the gunge has been displaced
An edge on view of the final hole after sanding would look like this:
Check the size by holding it flat behind a ruler with mm gradations up to a light.
Using a magnifying glass, (bit of a juggling act this) you should be able to accurately judge how many times the diameter of the hole will fit into the mm gap. (5 times = 0.2mm, 4 times = 0.25mm).
The smallest practical pinhole is around 0.18mm, any smaller and diffraction negates any increase in quality for which you can blame Isaac Newton!
Any well sanded hole with a sharp inside edge around 0.2mm will be fine.
It will probably be too big! (Ok I'm being rude here, but I have done this a few times) Have another go at making a smaller hole when you find you have messed the first one!
Holding the pinhole edge-on to the light and turning it until the light begins to appear through the hole will show you the angle of view the pinhole gives (important for wide angle imaging).
It is the 'sharpness' of the inside edge of the hole, (achieved by using the ultra fine emery paper), that gives the hole its quality, not merely the diameter of the hole. Luckily Lord Raleigh isn't around to argue with me on this one!
Choose the 'best' pinhole and cut out a rectangle with the pinhole in the centre to be taped on the front of your camera.