I have been wanting something like this for ages (wide angle converter that's behind the lens)

It wasn't really an argument, because that implies rationality. I corrected some of your more glaring misconceptions, and you fired off a stream of insults, at which point I concluded you were not capable of conducting a civil discussion.

To repeat: the Kodak patent is for a focal reducer that maintains the back focus of the original lens in order to clear an SLR mirror. Brian Caldwell's "speed booster" does not maintain the same back focus as the original lens, and is therefore, unencumbered by the Kodak patent.

And will it be a full stop faster? Put an 85mm f1.4 on one of these, and you get a 60mm f1.0. A 50mm f1.4 becomes a 35mm f1.0.  So, when you talk of the lenses that "you can buy", remember that there are things you can't buy, like Pentax mount f1.0 lenses.

It's not just the f1.0 lenses, either. There's the 13mm f2.0 (common 20mm f2.8).  I could go on, but I trust I've made my point.

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Rahon Klavanian 1912-2008. Armenian genocide survivor, amazing cook, scrabble master, and loving grandmother. You will be missed. Ciao! Joseph www.swissarmyfork.com