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Author Topic: Canon RF 85mm f/1.2 lens design  (Read 1094 times)

BJL

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Canon RF 85mm f/1.2 lens design
« on: January 21, 2020, 07:53:35 pm »

I jus noticed this schematic of the Canon RF 85mm f/1.2 and a couple of things are surprising or interesing to me.

Firstly, even at this long a focal length — more than twice as great as the depth of the Canon EF mount — there is apparently a design advantage to having elements right at the back of the lens body, far closer to the focal plane than any 35mm format SLR lens mount allows. So it seems that getting rid of the mirror benefits a wider range of of focal lengths than I expected, at least for very bright lenses like this f/1.2 and Nikon's 58mm f/0.95.

Secondly the rear elements occupy almost the full width of the mount, which is also true for the 58/0.95 Z, so some lens designs do indeed benefit from a wide throat; wider than Sony E-mount, it appears. Still probably only true for a few extremely bright  "statement" lenses like these though.
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kers

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    • Pieter Kers
Re: Canon RF 85mm f/1.2 lens design
« Reply #1 on: January 22, 2020, 11:11:13 am »

It is very nice to see so many new developments in lensdesign.
Nikon also is using this special blue ray coating like Canon. Others will follow.

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Pieter Kers
www.beeld.nu/la

BernardLanguillier

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Re: Canon RF 85mm f/1.2 lens design
« Reply #2 on: January 22, 2020, 03:32:57 pm »

It seems pretty clear by now that the claims of Nikon and Canon over Sony regarding the wider and more shallow mount do have a real and tangible impact on the quality and look that can be gained by these lenses.

The net result is that the only relevant question is when both brands will be able to catch up in terms of mirrorless AF.

Cheers,
Bernard

BJL

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Re: Canon RF 85mm f/1.2 lens design
« Reply #3 on: January 23, 2020, 09:10:47 pm »

It seems pretty clear by now that the claims of Nikon and Canon over Sony regarding the wider and more shallow mount do have a real and tangible impact on the quality and look that can be gained by these lenses.
Though perhaps for a few very fast lenses: the ones evidencing the advantage of a wider mount are f/1.2 or faster.
What is clearer is that—with Canon and Nikon having now joined the party—the highest quality lens systems are soon going to be ones for the new shallower lens mounts un-hampered by a TTL OVF, be they Canon, Nikon, Sony, Panasonic, Leica, Sigma or whoever.

Which leaves AF as the last ditch defense of high-end SLR cameras, so as you say:
The net result is that the only relevant question is when [Canon and Nikon] will be able to catch up in terms of mirrorless AF.
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Paul_Roark

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Re: Canon RF 85mm f/1.2 lens design
« Reply #4 on: January 24, 2020, 12:25:29 pm »

The new 85 f/1.2 has an impressive wide open MTF.  I once owned the older Canon series L 85mm f/1.2.  it wasn't bad either, but what caused me to sell it was the weight.  So, for those people like hikers or travel photographers, be sure you understand that this optic is going to weight over 3 times as much as an outstanding f/2.5 lens (the Leica-M 75mm, to be specific, which I've adapted to the Sony a7rii).  These super-fast optics are not for everyone, but there's no question low light photographers will benefit from the advances.

Paul
www.PaulRoark.com
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araucaria

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Re: Canon RF 85mm f/1.2 lens design
« Reply #5 on: March 08, 2020, 05:49:19 am »

Digital sensors benefit from telecentric rays.
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