Questions of the week

The real question of the week is Amy's: What have the Brontës to do with photography?
Answers on the Blog, please.

But there are also questions about lenses. If a pinhole can make a picture, why do we need lenses?

One reason is sharpness- pinhole images are always slightly fuzzy, because light is scattered around the edges of the hole.

Also, pinhole exposures are very slow, because so little light actually gets through the hole (remember how that super-bright 1000 Watt lamp produced quite a dark upside-down image of itself on the white card?).

A glass lens can let a lot of light through, compared to a pinhole, and so allows the short exposures that we all take for granted.

Although most photographic lenses are mass-produced, one-off lenses can be made for special purposes like our own giant camera. Our lens was designed by a professional lens-designer in order to fit this camera obscura tent - specifically, to provide a 3ft square image at a distance of 4ft from the lens.

I hope it works!