# Patent: 500mm and 600mm diffractive optic lenses



## Canon Rumors Guy (Dec 28, 2018)

> Here is another in a long line of diffractive optics patents we’ve seen from Canon over the last couple of years. Since the Canon EXPO in 2015, we’ve all been wondering where the EF 600mm f/4 DO IS lens is, a lens we don’t think is ever coming at this point. A lot has changed over the last 3 years, and we expect any new DO super telephoto lens to be for Canon’s new RF mount.
> This latest USPTO patent showcases both a 500mm and 600mm optical formula. As Canon News points out, this patent shows Canon moving the lens elements closer to the camera body to improve balance. This is the same sort of design we saw in the brand new EF 400mm f/2.8L IS III and EF 600mm f/4L IS III lenses.
> *Example 1:*
> 
> ...



Continue reading...


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## wtlloyd (Dec 28, 2018)

"where the EF 600mm f/4 DO IS lens is, a lens we don’t think is ever coming "
Ya, pretty much. Why would they, with the new VerIII lens weight reduction. If a DO 600mm ever comes, it'll be RF mount.


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## DanCarr (Dec 28, 2018)

The odd thing about these is that they are actually listed as being physically longer than existing non-DO 500 and 600s.


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## applecider (Dec 28, 2018)

I get that ML is the new platform, but EF lenses are so adaptable and the R are good only for the very short back focus. Is it just sour grapes that I want EF lenses or is canon pulling an FD to EF switch in a sort of non mandatory way. That switch gained autofocus, this one gets higher frame rates, better servo focus, less expensive lenses. Lighter equipment.

Is there a third party lens for the R mount yet?

I thought that canon was way ahead of Nikon in the DO space, but right now it looks like a leap frogging situation.


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## Mr Majestyk (Dec 29, 2018)

Why release 400/600 mk III in EF and not a 300/500 mk III in EF. Currently, we have no idea if Canon can even offer an RF mount camera worthy of such lenses. They need a quantum leap over the pitiful EOS R AF system to make it worthwhile. Also could these be made much lighter than refractive counterparts? 600III is 3kg, unless you can get that down under 2.7kg and physically shorter is it worth it? Now if they can deliver a 500 f/4 DO at around 2-2.3kg and offer Sony A9 class AF in an EOS R then I'll be first in line.


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## RGF (Dec 29, 2018)

To release a RF mount supertele Canon will need an R body with high FPS for action. This should be interesting ... in 3 to 5 years


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## AlanF (Dec 29, 2018)

The lens I would lust after would be a rival to the Nikkor 500mm f/5.6 PF (DO equivalent). It's close to the same length as the 400mm DO II (237mm), weighs only 1.46 kg (vs 2.1 kg + 200g hood of DO) and takes 95mm filters. It's lighter than the 100-400mm II f/5.6. And a diminutive 400 f/5.6 DO under a kg would be irresistible.


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## edoorn (Dec 29, 2018)

I could see a 500 DO in RF mount in my future


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## sulla (Dec 29, 2018)

"we expect any new DO super telephoto lens to be for Canon’s new RF mount"

Why should it? RF mount is perfect for lenses with a short backfocus, like lenses with a focal length of up to ~100 mm. I don't see a benefit of the RF mount for longer lenses: (super) telephoto lenses have a huge backfocus anyway (as is also shown in this patent), that makes them perfectly suited for the EF mount. I think it makes just more sense to make those lenses physically shorter EF lenses an use an adapter for RF mounts than make them physically longer (with an empty tube at the back) and make them RF-natively. At most, Canon could release EF- and RF- supertelephotolenses of the very same design just a different end-barrel (plus offer a mount conversion service).

The only advantage I can imagine could come from the (slightly) larger mount diameter of the RF mount, but I have no idea whether that makes designing RF-supertelephoto lenses easier than EF-supertelephoto lenses. But it could be... But for the back focus: no!


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## Joules (Dec 29, 2018)

sulla said:


> The only advantage I can imagine could come from the (slightly) larger mount diameter of the RF mount, but I have no idea whether that makes designing RF-supertelephoto lenses easier than EF-supertelephoto lenses.


Correct me if I'm wrong, but is the RF mount not the same in diameter as the EF mount? Wikipedia and the Canon page where they announced the new mount both list 54mm as the inner diameter for both mounts.

So apart from avoiding the use of an adapter there should be no mechanical/optical advantage to making an RF supertele lens over an EF one.

The note from DanCarr about the sizes is interesting. According to the Canon Website the current 600mm III is 448mm long and the post above suggests the DO version would be 474mm long. Am I missing something about the way these are measured?

The increase could be explained in part by the addition of 24mm empty tube to an RF lens. But if a DO Version actually becomes bigger than its regular counterpart, I imagine the weight the reduction would have to be really significant to still sell well.


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## docsmith (Dec 29, 2018)

Joules said:


> The note from DanCarr about the sizes is interesting. According to the Canon Website the current 600mm III is 448mm long and the post above suggests the DO version would be 474mm long. Am I missing something about the way these are measured?
> 
> The increase could be explained in part by the addition of 24mm empty tube to an RF lens.


If that is it, I would almost rather have EF supertelephotos and use an adapter. That would make packing/travel a bit easier.


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## sulla (Dec 29, 2018)

The previous post
https://www.canonrumors.com/the-benefits-of-the-large-diameter-of-the-eos-rs-rf-mount-explained/
explains, that the RF mount is larger than the _EF-M_ mount.

UPS. I confused EF-M with EF/EF-S. Yes, indeed, RF and EF mounts have the same inner diameter of 54mm.

So, really _no _reason I see to make large backfocus lenses with a native RF mount...


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## koenkooi (Dec 29, 2018)

sulla said:


> The previous post
> https://www.canonrumors.com/the-benefits-of-the-large-diameter-of-the-eos-rs-rf-mount-explained/
> explains, that the RF mount is larger than the _EF-M_ mount.
> 
> ...



No technical/mechanical reason you mean. Plenty of business and marketing reasons to make it an RF lens.


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## sulla (Dec 29, 2018)

koenkooi said:


> No technical/mechanical reason you mean. Plenty of business and marketing reasons to make it an RF lens.


yes, of course...


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## Tom W (Dec 29, 2018)

DanCarr said:


> The odd thing about these is that they are actually listed as being physically longer than existing non-DO 500 and 600s.



I checked, and saw that. Unless the length would include the hood, I don't see the advantage. The 500 f/4 II IS is an awesome lens. Lightening and/or reducing the size is what it needs. But if they do to it what they did to the 400 and 600, then I'm not sure that there's a place for DO.


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## Tom W (Dec 29, 2018)

sulla said:


> The previous post
> https://www.canonrumors.com/the-benefits-of-the-large-diameter-of-the-eos-rs-rf-mount-explained/
> explains, that the RF mount is larger than the _EF-M_ mount.
> 
> ...



They could easily make any of the super-telephoto lenses in either EF or R mount as the situation demands. The backfocus distance is much larger than the spacing between the lens and sensor on either mount. 

The big differences would be no adapter needed for the R mount, and the additional communications that R offers between the lens and the camera. Optically, they could essentially be identical.


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## Architect1776 (Dec 29, 2018)

sulla said:


> "we expect any new DO super telephoto lens to be for Canon’s new RF mount"
> 
> Why should it? RF mount is perfect for lenses with a short backfocus, like lenses with a focal length of up to ~100 mm. I don't see a benefit of the RF mount for longer lenses: (super) telephoto lenses have a huge backfocus anyway (as is also shown in this patent), that makes them perfectly suited for the EF mount. I think it makes just more sense to make those lenses physically shorter EF lenses an use an adapter for RF mounts than make them physically longer (with an empty tube at the back) and make them RF-natively. At most, Canon could release EF- and RF- supertelephotolenses of the very same design just a different end-barrel (plus offer a mount conversion service).
> 
> The only advantage I can imagine could come from the (slightly) larger mount diameter of the RF mount, but I have no idea whether that makes designing RF-supertelephoto lenses easier than EF-supertelephoto lenses. But it could be... But for the back focus: no!



EF and RF mount diameter are identical 54mm.


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## Architect1776 (Dec 29, 2018)

Joules said:


> Correct me if I'm wrong, but is the RF mount not the same in diameter as the EF mount? Wikipedia and the Canon page where they announced the new mount both list 54mm as the inner diameter for both mounts.
> 
> So apart from avoiding the use of an adapter there should be no mechanical/optical advantage to making an RF supertele lens over an EF one.
> 
> ...



EF and RF are 54mm in diameter.


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## juststeve (Dec 29, 2018)

I am currently renting an R and the 24-105/4 L This past week I spent two days photographing bald eagles, mostly in flight, using the R, the control ring adapter and a 500/4 L ii with and without a 1.4x.

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.

Also, I photographed my border collies chasing frizbees. I did it from in front of the dogs near where they were making their catches, using the RF 24-105/4. When I performed keeping the camera on target well, the camera focus system performed well. Same as with the flying eagles. I found interesting the camera did not seem to have the viewfinder stutter at 5 fps with the RF lens. Perhaps the capability of much higher rate communication between lens and camera with the RF mount explains this. This would certainly make purchase of fancy DO RF lenses tempting. Likely increase the divorce rate, too.


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## lexptr (Dec 29, 2018)

I see news and rumors about those two again and again but still don't get the point. They add DO while, unlike with 400mm, retain the same max aperture. So, I guess, it will be even more expensive and have narrower customers niche. So, what for? With their recent advancements in weight reduction of mark III versions, the possible specs-profit is even smaller.

What could be interesting to many, I think, is adding some good cheaper options. E.g. 500mm f/5.6 DO (like the Nikon's one) or 200-600mm f/4.5-5.6 (a rumored "larger" 100-400mm). Here I can see a source of possible hesitation (aside from development difficulties and times) - fear to draw some customers from their more expensive lenses. On other hand, many will buy such lenses for sure. I would. And this wouldn't draw me from expensive super-tele, since I don't think I will ever justify five-figure price for a single lens.


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## Mikehit (Dec 29, 2018)

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?


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## JoseB (Dec 29, 2018)

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.


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## AlanF (Dec 29, 2018)

JoseB said:


> 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.


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## Jack Douglas (Dec 30, 2018)

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

Jack


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## snoke (Dec 30, 2018)

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


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## mb66energy (Dec 30, 2018)

juststeve said:


> [...] 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.


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## mb66energy (Dec 30, 2018)

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.


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## Ale_F (Dec 31, 2018)

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....


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