And then how to use it.
For Worldwide Pinhole Day I constructed a pinhole camera from a shoebox, took some shots on photographic paper, then developed and scanned the resulting paper negatives. Here’s how I got on.
First, I used the Pinhole Camera Design Wizard from Mr Pinhole. Taking into account the paper size – 13 x 18 cm and the available shoe boxes I worked out that I could use a focal length (that’s the distance from the back of the box to the front) of 21 cm and a pinhole of 0.61mm or f/344.
If you have some sewing needles of known sizes you work out which one to use from the handy chart at the Pinhole Gallery. It also has an exposure guide that will be useful later.
My needles weren’t labelled but luckily I live with someone who owns a micrometer.

Micrometer and correctly sized needle
So (or sew if you prefer) on to the construction. My box had a folding lid that I thought would work well as it was, so all I did was cut a square out of the side of the box where the pinhole will go -hint, that’s the hinged side, not the side where the flap will close to!

Cutting the hole for the pinhole plate.
Then I made sure it was light-tight by taping up all the seams. I used a sheet of black paper to line the inside – but it’s not strictly necessary.
Next I cut a rough square from a soft drinks can. I made it a fair bit bigger than the hole I’d made in the box – it will be taped to the inside of the box to make the “lens”.

Cutting out the pinhole plate
I used a ball-point pen to mark the centre of the plate, and used the needle, pressing it gently and pushing through on both sides to make the hole.

The finished pinhole plate
A quick test by holding it up to the light and voilà – it works. So I taped it to the inside of the box and cut a lens cap from a square of card, which I fixed to the outside of the box.

The view through the pinhole
Then I put 4 blobs of blu tak on the opposite side of the box, lining them up so they will hold the sheet of paper in place.
Now, into the darkroom with the box and some gaffa tape. Using only the safelight, I got out a sheet of photographic paper and pressed it onto the blu tak. I closed the lid and sealed the box down all the way around to prevent any light leaks.
The only thing left to do was to set the camera up and make some exposures.

Pinhole camera in use
This is where the exposure chart comes in. Photographic paper has an ISO of around 6 which is pretty slow so you’ll be exposing for minutes at a time rather than fractions of a second. To start the exposure, simply remove the lens cap and start timing. Don’t forget to stick it back over the pinhole when you’re done.
You’ll need to take the camera back into the darkroom to unload the paper and develop it.
When it’s dry you’ll end up with a paper negative like this:

Paper negative
If you’re a purist (and you have an enlarger) you can put it under the enlarger to make a positive print. I skipped that step and scanned and inverted the negative to get this:

The finished article
In fact it was such good fun that I did it all over again and got this.

Rain streaked windows by pinhole
Like this:
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