The best selection is in 49mm, with smaller quantities of lots of other sizes.

I think the reason is that we needed a frame of reference for what a lens would do, in the early days of digital photography. At this point cameras were compacts or bridge cameras and they all had different sensor sizes. This meant the focal lengths meant almost nothing to anybody, so the idea of "35mm equivalent" was born.

I'm pleased that at least Pentax continued to mark the actual focal lengths on their lenses though, because some makers label them with the "35mm equivalent" and I find that quite annoying.

I like to keep life simple, so even polarisers are the same price. Sadly, I can only find a 62mm linear polariser.

I have a reasonably large number of filters in 49mm, 52mm, 55mm, 58mm and some larger ones up to 86mm.

UK only, £3 each up to 55mm, £5 each 58mm and larger. Free shipping in UK.

If you have any requirements, please ask and I'll see if I can find what you want. They are too numerous to list.

Yes, 1....I was pretty surprised as well.

I've had some success selling Kodak and Ilford glass plates dated as long ago as 1948....

Apparently exposed at ISO 1 they are quite usable!

A good choice to opt for black and white. I like the shots, all apart from whatever you've done to the top part of #4....I'm afraid that looks a bit of a mess and spoils the shot.

The Darkroom Ltd run a quality service, as do many others.

If there's an aperture ring, also double check it is still set to "A".

Andrew has a good point there. It's an amazing lens and costs very little.