Hello,

I am wondering if anybody here knows about a 50mm/0.9 lens that has the EF mount?

~Sarah

I haven't heard of such a thing. Canon used to make a 50mm f/1 L in EF mount. They also used to make a 50mm f/0.95 for their rangefinder cameras.

--Geoff

Thank you for the quick response. The thing is that I am almost sure something like that exists. I once saw a theater photographer using one of these and he said it was a Zeiss lens as far as I remember.

Geoff is correct,

The lens you might be thinking of is likely this one.
http://www.canon.com/camera-museum/camera/lens/s/data/50-85/s_50_095.html

The fastest EF mount made so far was indeed the 50mm f/1
http://www.canon.com/camera-museum/camera/lens/ef/data/standard/ef_50_10l_usm.html

Zeiss did make a 50mm f/0.7, but to my recollection they only made a handful of them. I know Stanley Kubrick used a modified one for one of his films.

I think you guys are indeed right, the S-mount CANON 50mm f/0.95 looks a lot like the one he was using. Thank you!

I should also mention that I saw the guy shooting with this lens about 10-12 years ago. So my memory of this isn't the freshest.

The Canon 50mm f/0.95 S-mount is for a rangefinder, and if used on an EF mount it wouldn't be able to get anywhere near infinity focus. People use them on Leica M8 and M9 cameras.