There's been some discussion on the optical design of the objective in this thread. I'm an actual optical designer, but not involved with Canon in any other way than that I just happened to select Canon's camera (20D) in 2006 and have been on that path ever since.
The most straight-forward objective type to design is the normal focal length, that is to say, objective focal length is approximately the same as the sensor diagonal (43.2 mm in full-frame). No doubt you can make it harder with some extra requirements like macro and low F-number, but typically this tends to work out so.
Telephotos are easier in a sense you typically need less elements and aspheres (barring telephoto zooms that can become quite complex), but the difficulty lies in the material requirements and centering tolerances. Two typical aberrations to combat against are spherical aberration and longitudal color; that's where calcium fluoride comes in to play. The focusing mechanism is also occasionally difficult as the mass moving should be minimized, and this is not easy to do always. Telephoto is a bit more stringent in the mechanics and assembly, but somewhat more easier to design optically.
Rectilinear wide-angles are demanding in a sense that there's usually no-avoiding aspheres, and the shorter the focal length, the harder it gets to correct for the distortion. Add in lateral color correction, and ultra-wide primes can become very challenging to design and require a lot of design and optimization time. Ultra-wide zooms are then another tale to tell.
However, the departure from 50 mm to 35 mm or 85 mm is not yet massive. These are still relatively normal focal lengths where the other requires a bit more positive power in front of the aperture stop, and the other a bit more negative.
I do believe the EF85/1.4 IS will be more expensive than EF85/1.2 II. I'm guessing 1.5x - 2x the current objective price. The reason lies in the image stabilizer; 85 mm objective at F/1.4 with a stabilizer is no easy feat, specifically if Canon is upgrading the objective resolution - which they'll likely do. Hopefully the its bokeh remains good, that seems to suffer with stabilized objectives. It does make me wonder whether EF85/1.4 IS is going to be focus by wire. Whether 85/1.4 includes BR remains to be seen.
The most straight-forward objective type to design is the normal focal length, that is to say, objective focal length is approximately the same as the sensor diagonal (43.2 mm in full-frame). No doubt you can make it harder with some extra requirements like macro and low F-number, but typically this tends to work out so.
Telephotos are easier in a sense you typically need less elements and aspheres (barring telephoto zooms that can become quite complex), but the difficulty lies in the material requirements and centering tolerances. Two typical aberrations to combat against are spherical aberration and longitudal color; that's where calcium fluoride comes in to play. The focusing mechanism is also occasionally difficult as the mass moving should be minimized, and this is not easy to do always. Telephoto is a bit more stringent in the mechanics and assembly, but somewhat more easier to design optically.
Rectilinear wide-angles are demanding in a sense that there's usually no-avoiding aspheres, and the shorter the focal length, the harder it gets to correct for the distortion. Add in lateral color correction, and ultra-wide primes can become very challenging to design and require a lot of design and optimization time. Ultra-wide zooms are then another tale to tell.
However, the departure from 50 mm to 35 mm or 85 mm is not yet massive. These are still relatively normal focal lengths where the other requires a bit more positive power in front of the aperture stop, and the other a bit more negative.
I do believe the EF85/1.4 IS will be more expensive than EF85/1.2 II. I'm guessing 1.5x - 2x the current objective price. The reason lies in the image stabilizer; 85 mm objective at F/1.4 with a stabilizer is no easy feat, specifically if Canon is upgrading the objective resolution - which they'll likely do. Hopefully the its bokeh remains good, that seems to suffer with stabilized objectives. It does make me wonder whether EF85/1.4 IS is going to be focus by wire. Whether 85/1.4 includes BR remains to be seen.
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