Architect1776 Loc: In my mind

You are welcome.
Part of this forum is to learn or see new things.

rmorrison1116 Loc: Near Valley Forge, Pennsylvania

The Canon 85 1.2 is not a general purpose lens and anyone who uses it that way isn't very lens savy. It's a lens to be used on things that aren't moving. You can't apply everyday practical parameters to a specialty lens, that would be setting it up to fail. Is a small flat head screw driver capable of turning a Phillips screw? Probably. Will it do as good a job or better than a Phillips screw driver? Absolutely not.

burkphoto Loc: High Point, NC

On m43 cameras, a 42.5mm Leica f/1.2 lens is less than 1/3 as large... Rear element is 1/4 the area. Same field of view from the same distance as 85 on full frame.

Architect1776 Loc: In my mind

Physics?
How does it work with a smaller opening?
You have great answers, see if I can stump you this time.

Ira

The DXO comparison that Oldtigger posted wasn't a fair comparison. He put the 36megapixel D800e against the 22megapixel 5D mark lll.
A better comparison would be between the D750(24mp) and the 5D mark lll(22mp).
http://www.dxomark.com/Lenses/Compare/Side-by-side/Nikkor-AF-S-NIKKOR-85mm-f14G-on-Nikon-D750-versus-EF85mm-f-1.2L-II-USM-on-Canon-EOS-5D-Mark-III__388_975_270_795
This still shows the nikon lens as being much sharper.
Nikon does make a f1.2 in a 50mm. Nikon's rear mount opening is much larger then it's full frame sensor, how much larger does it need to be? When they start making larger format cameras is when they will need to change their mount.

This is an interesting comparison:

http://www.dxomark.com/Lenses/Compare/Side-by-side/Nikkor-AF-S-NIKKOR-85mm-f14G-on-Nikon-D750-versus-EF85mm-f-1.2L-II-USM-on-Canon-EOS-5D-Mark-III-versus-Zeiss-Carl-Zeiss-Apo-Planar-T-Star-Otus-85mm-F14-ZE-Canon-on-Canon-EOS-5D-Mark-III__388_975_270_795_1383_795

oldtigger Loc: Roanoke Virginia-USA

Time to educate me.
I always thought the MTF curves were derived without a camera body.

amfoto1 Loc: San Jose, Calif. USA

This is a perfect example of where the DXOmark method of lens evaluation fails big time.

The Canon 85/1.2L II is about the defocused areas, as much or more than the shallow plane of focus. In other words, sharpness isn't everything! How a lens renders softness can be just as important or even more-so.

I don't use the 85/1.2L for several reasons... it's big, heavy and quite expensive, plus those huge front and rear elements are vulnerable. But it's also slower focusing... by design. To accommodate the potentially shallow DoF, it uses a long throw focus design that emphasizes accuracy over speed. At least the II is faster focusing than the original (or the older 50/1.0L). It's also a "fly-by-wire" focus design, needs to be powered up even to manually focus it (i.e., camera needs to be on and "awake").

The 85/1.2L is pretty much an uncompromising portrait lens for someone like wedding and glamour photographers wanting a really dreamy look. The 50/1.2L is similar. To a lesser extent, the 24/1.4L, 35/1.4L and 135/2L are too, when used wide open (though they are all much faster focusing and more versatile).

Someone wanting an 85mm that will also serve for sports and other purposes would do better to look at the f1.8 or f1.4 variants. Nikon used to make an excellent f2.0, too. All those can serve more purposes, are more versatile. But someone wanting that really dreamy look, the 85/1.2 can produce images like few other lenses.

amfoto1 Loc: San Jose, Calif. USA

Yeah, that's correct. It's not true that the rear element size possible with the Canon EF is essential for an f1.2 lens.

While the Canon is the only auto focus and electronically controlled aperture 85/1.2 currently in production, there have been a number of different f1.2 (and f1.1, f1.0, even f0.95) standard lenses over the years from most manufacturers.

I have a couple Konica Hexanon 57mm f/1.2 in my collection. I know for certain there were also Nikkor 50/1.2, Minolta 58/1.2, Canon FL 55/1.2, Pentax-A SMC 50/1.2, Olympus OM 50/1.2 and more.

Canon themselves made an 85mm f1.2 in their earlier and smaller diameter FD mount.

Apparently Zenit is making a comeback, too, this year... Starting with some ultra-fast lenses: 50/0.95, 50/1.2 and an 85/1.2. These will all be manual focus only and the 50/0.95 is expected to be only in Sony FE mirrorless mount. The other two are for full frame or APS-C DSLRs and expected to be available for Canon and Nikon mounts.

There also is currently a manual focus Mitakon 85/1.2 available in Canon, Nikon, Sony FE and Sony A mounts.

wj cody Loc: springfield illinois

just for edification, minolta made their own glass - their operation was the Imari glass works. glass so good it was used in leica's slr cameras from 1972 onwards.

jerryc41 Loc: Catskill Mts of NY

Or bragging rights? Maybe some people just need that extra stop for the type of shooting they do.

rfmaude41 Loc: Lancaster, Texas (DFW area)

Nikon used to make a 58mm f/1.2

rfmaude41 Loc: Lancaster, Texas (DFW area)

It's only a half-stop difference...

Kmgw9v Loc: Miami, Florida

Perhaps not relevant, but Nikon does make a 58 mm 1.4.

foathog Loc: Greensboro, NC

Isn't it obvious???? The Canon is MUCH better. you get more for your money. What an exciting question.

SharpShooter Loc: NorCal

Unfortunately, for many amatuer photographers, sharpness is all there is! Thus places like DXO become their defacto bibles. Advanced photographers know that at times sharpness has no bearing and art becomes all important.
There will always be those that just don't get it!
SS