Waterhouse

Waterhouse

Specifically, John Waterhouse of Halifax, who thought up the idea of having a slot in the side of a lens to insert plates to control the aperture of a lens in 1858, according to Wikipedia.

Previously, it was necessary to unscrew the lens to insert the aperture control plates: Waterhouse clearly improved the ergonomics quite a bit!

That’s what the internet research threw up, and I didn’t know any of it: I was, though, familiar with the idea of a plate or plates with fixed aperture(s).



My Ilford Manual (yes, it’s still between my keyboard and screen) refers to Waterhouse stops as an alternative to either a conventional iris diaphragm (which uses a series of blades that rotate in the lens mount and adjust the size of the light-transmitting area) or a plate with multiple holes in it.

However, I’ve been used to using the term to describe any sort of aperture control that involves fixed holes rather than diaphragm blades, and I may not be the only photographer to make this mistake!
Accepting the wider definition, I first met Waterhouse stops in a Kodak Brownie movie camera, which went from f/2.7 to f/22 in half-stop increments, with guidance round the lens for different light conditions.



And, for many years, that was it: and then I bought my first Lensbaby. Now, most Lensbaby optics have conventional diaphragms, but a few have Waterhouse stops made of the same sort of steel/plastic combination as flexible fridge magnets, so they can held in position by three small magnets in the front of the lens.

Lensbaby have extended the idea to include unconventional shapes that give characteristic out-of-focus highlights – hearts for Valentine’s Day portraits and so on.

The advantage of a Waterhouse stop, clearly, is that it allows a perfectly circular aperture: the disadvantage, clearly, is that they are much slower to adjust than a conventional diaphragm, so that they are now confined to special purposes.

The idea lives on, though, in the way that a few long lenses have a slot in the side to allow the user to insert filters in the middle of the optical system, instead of at the front. For a telephoto lens, this can make a big difference between a filter that’s a couple of centimetres across, and one that is 10cm or more…