Patent: 500mm and 600mm diffractive optic lenses

[Mikehit]

AF results from active communication between lens and body. Canon has a history of including in their lenses some technology that supports technology that ison teh drawing board for future body releases, so I would not be surprised if the new 400 f2.8 or the 6000 f4 mkiii will work better with the EOS-R than the 500mkii does.
But where does this leave the DO lenses?

The excellent 400 f4 DO weighs 2.1kg. The 600 f4mkiii is under 3kg (lighter than the 500 mk ii) so how much weight can they save with DO technology?

 

[JoseB]

The goal of DO technology is to reduce chromatic aberrations and reduce the number of optical elements. Reducing weight and dimensions is a side effect.

 

[AlanF]

The goal of DO technology is to reduce chromatic aberrations and reduce the number of optical elements. Reducing weight and dimensions is a side effect.

Where has Canon stated that is its goal? This is what I have seen Canon write: http://www.canon.com/technology/now/input/ef.html
"DO Lens
A Compact, Reduced-Weight Telephoto Lens
The Diffractive Optics (DO) lens for SLR cameras is designed to utilize the opposing chromatic dispersion patterns of diffractive and refractive optical systems built into the lens. Canon has applied optical principles to substantially reduce both the size and weight of this telephoto lens for SLR cameras.",
which reads like size and weight reduction is the goal and the DO is a means of achieving this. There are traditional ways of reducing chromatic aberration that Canon overwhelmingly uses when it is not concerned about weight and size.

 

[Jack Douglas]

Makes me wonder what a F4 non-DO 400 lens would be like in comparison.

Jack

 

[snoke]

Why make big lens RF?
RF talk fast to camera.
EF talk slow to camera.
AF/AI servo better on RF?

 

[mb66energy]

[...] Those who claim the R focuses poorly should perhaps use one for a bit of time in real photo world conditions. For me the camera focused the 500 very, very well, at least on par with my 7D ii and 5DS, and likely better. Yes, there is a bit of a stutter in the viewfinder at 5 fps. I found it minor and did not hinder me. If it had I would have switched out camera bodies. Instead, I used it for nearly 900 exposures.
[...]

Good to read good things about the AF of the EOS R! In the morning I just thought about framerates and came to the following conclusion: What is better? 15 fps with 33% hit rate or 5 fps with 100% hit rate? - for me it would be the latter case because I know what I get. And it would help me to reduce the number of photos to choose from.

 

[mb66energy]

Surprised to see two (two!) aspherical lenses in a long tele lens. But after checking the (japanese) Canon site the existing 400mm DO lens has it too so maybe it compensates other aberrations which DO produces (or which are prominent due to the DO element requirements).
Maybe this helps to reduce the "large diameter lens" count to only three (lenses) which might reduce the weight dramatically despite slightly larger size.

 

[Ale_F]

I think the new lenses will be optimized for RF (more contacts) but actually they NEED to be EF, just for market. It's easy to convert EF to RF but no viceversa. Since we have not R sport camera(s), the easy solution for long backfocus lenses is to make EF mount.
Another solution could be two version of the same lens....