# Patent: More diffractive optics super telephoto lenses



## Canon Rumors Guy (Feb 22, 2019)

> I’ll be honest, the first 20 or so patents relating to diffractive optics lenses had me excited about what was coming down the pipeline. However, the last bunch of patents for DO optical formulas hasn’t really given me a lot of hope that we’re going to see new and exciting super telephoto lenses from Canon.
> Below are three embodiments that show 400mm, 600mm, and 800mm DO optical formulas.
> Japan Patent Application 2019-028317
> *Canon 600mm f/4 DO IS*
> ...



Continue reading...


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## tron (Feb 22, 2019)

These are BS! The current 400mm DO f/4 IS has 22cm length not ... 33!
I do have it and it is exceptional! Why should I be so stupid to update it with a model 50% longer???
And the 600mm f/4 IS DO prototype was 31cm long not 39!
Unless the mentioned numbers are not really length but the distance from the sensor. The text mentions "whole length" which I have never seen before. Normally "length" is enough. I guess these are patents in addition to ... other patents so we will not see anything in the near future anyway.


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## criscokkat (Feb 22, 2019)

tron said:


> These are BS! The current 400mm DO f/4 IS has 22cm length not ... 33!
> I do have it and it is exceptional! Why should I be so stupid to update it with a model 50% longer???
> And the 600mm f/4 IS DO prototype was 31cm long not 39!
> Unless the mentioned numbers are not really length but the distance from the sensor. The text mentions "whole length" which I have never seen before. Normally "length" is enough. I guess these are patents in addition to ... other patents so we will not see anything in the near future anyway.


Even if you added the registration distance of the old EF lenses to this length you still come up with something much longer.

Perhaps these are new not-so-drastic DO like lenses that are meant to replace the current 400/600 EF lens without the optical quality difference between the versions?


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## BeenThere (Feb 22, 2019)

Lots of patents and no HW releases. Seem to be protecting IP of an active design group.


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## Lurker (Feb 22, 2019)

Canon just bores me now, I don't expect them to do anything interesting for me ever again. Development announcements, Half baked and lower end cameras, just don't do it for me.

I'm much more interested in the 3rd party vendor news.


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## Mt Spokane Photography (Feb 22, 2019)

This patent uses a different combination of gratings then I've seen before. They are said to reduce the diameter of the lens. Its a trade off, reduce length or reduce diameter, the goal of this one is to reduce diameter, which might make a lens less expensive, but longer. Here are some snippets from the patent which talk smaller diameter.

"In the optical system containing a diffraction optical element, the object of this invention is small-diameter-izing a diffraction optical element, correcting several aberrations including a chromatic aberration satisfactorily."

The front diffraction grating is a Blaze type Grating, the second is just referred to a diffraction grating. 


BTW, lengths are specified as whole length, every lens patent is specified like this, its nothing new. But, they still tell you this in the patent. Its the length from the front optical element to the sensor plane. BF is the length from the last lens element to the sensor plane, it is not the flange distance.

From what I see, the most likely lens to appear is the 600mm f/4 DO. Its a lot shorter while there appears to be no length advantage to the 800mm, and the 400mm is longer than the existing DO lens.

In the* first *example, we have a 600mm f/4 with a 394mm whole length and a back focus of 63mm, the back focus being the distance from the rear optical element to the sensor plane.

The existing 600mm f/4 is 448mm (457mm fully extended), so the new design is a lot shorter once you add the 44mm flange distance.


Various data
Focal distance 582.00 
F number 4.12 
Half field angle (degree) 2.13 
Image height 21.64 
Whole length of the lens 394.25 
BF 62.79




In the* second *example, we have a 400mm f/4 with a 330mm whole length and a back focus of 50mm, the back focus being the distance from the rear optical element to the sensor plane.

The existing 400mm D) II f/4 is 233mm (240mm fully extended), so the new design is longer once you add the 44mm flange distance. *Its pretty certain that it won't appear unless its lighter and cheaper.*

Various data
Focal distance 405.00 
F number 4.12 
Half field angle (degree) 3.06 
Image height 21.64 
Whole length of the lens 330.16 
BF 50.46



In the *third* example, we have a 800mm f/5.6 with a 490mm whole length and a back focus of 105.13mm, the back focus being the distance from the rear optical element to the sensor plane.

The existing 800mm f/5.6 is 461mm (472 mm fully extended), so the new design is only slightly shorter once you add the 44mm flange distance. * I doubt we'd see it either unless its a lot lighter and cheaper.*

Various data
Focal distance 795.00 
F number 5.60 
Half field angle (degree) 1.56 
Image height 21.64 
Whole length of the lens 490.24 
BF 105.13


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## Mt Spokane Photography (Feb 22, 2019)

BeenThere said:


> Lots of patents and no HW releases. Seem to be protecting IP of an active design group.


Canon has about 2000 patents a year. Few result in hardware. This applies to vrtually every patent on the earth. They exist because they protect investment into a design, and a piece of a patent can be incorporated into hardware and still be protected, or manufacturing / materials costs may suddenly change and make a design practical to manufacture.


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## Lurker (Feb 22, 2019)

SwissFrank said:


> What was the last lens by anybody as jaw-dropping as the 28-70/2? Or the MTF bokeh etc. of the 1.2? Serious question. (I personally would like a pancake lens, but I'm getting an adapter for the Leica 35/1.4 which is going to be small enough to have mounted any time the 24-105 is too big.)



RF.

All depends on your perspective. RF is an immature system that will take years to fill out. I'm not willing to play the waiting game. RF has some really great stuff and has a really bright future but I highly doubt it will play any role in my future. There are lots of companies out there creating great new products/services that I'll never use so they just don't excite me.

At 57, and a hobbyist, I'm only interested in what Canon is doing for me now. I waited for years to upgrade my kit when opportunity finally knocked this last fall. Since then I've bought a 5D IV, 100-400 II, 400 DO II, 24-105 II, 600 EX II RT, Pixma Pro 100, Tamron 24-70 G2 and Tamron 15-30 G2. I already had the Canon 70-200 f/2.8 II, 100mm Macro and the Canon III TCs. The only things I'm really interested in are an affordable/useable (for me) 600mm and a second body (7D III?). A new 180mm macro might get me to bite and if I get a GAS attack maybe a TS lens. The ND filter revolution is also exciting.


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## Jack Douglas (Feb 23, 2019)

It boggles my mind how anyone can be unhappy with a bunch of Canon's top of the line gear. I would think they'd be so busy producing jaw dropping photos they wouldn't have time to even consider the shortcomings. 

Certainly, what I'm using exceeds my creative capabilities but that's just me and as much as I'm interested in exciting developments I just can't jump on any half baked bandwagon. 

I love to see photos that demonstrate what's stated in words. Repeatedly we here testimonies that it's not possible to discern which camera has produced which properly exposed photo and yet folk are bemoaning there fate as if the difference is huge. 

Jack


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## tron (Feb 24, 2019)

Jack I do have and enjoy both 500 f/4 IS II and 400 DO f/4 IS II. I know you have and enjoy the later. The reason you bought it is that it is light and small (in addition to having top notch IQ of course).
Would you get it all the same if it was 33cm instead of 22cm long (and most probably much heavier due to excess length)? This was what my protest was about!


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## Jack Douglas (Feb 24, 2019)

Tron, If there was nothing else I don't think the length would be as much of an issue as the weight. Sometimes a long hand held wait for an expected flight etc. gets pretty tiring as it is. For me now, weight factors into all my choices and is a slight negative for the 1DX2. Certainly going 6D to 1DX2 was a negative only for weight; size is not an issue. I certainly don't regret the 400 DO II although kind of having to part with the 300 was a slight negative but for birds, 400 is better.

I include myself in saying this. Having a ton of great gear doesn't make one a better photographer unless you're fully capable of extracting the maximum from it and the same goes for lusting after every new highly rated arrival. Comments about a new arrival _obsoleting_ a perfectly good previous generation camera or lens are utter nonsense! That's how you explode GAS - remind yourself of the previous sentence.

Jack


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## tron (Feb 24, 2019)

Jack I find the weight of 400 DO very useful in portability but at the same time its short length makes me holding it much more comfortable. My left hand does not get tired since I do not extend it much and it stays close to body (which also helps in stability). At the same time the 400 can be put in very reasonably sized bags. Add it's superb IQ and it is my favorite excursion lens.


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## AlanF (Feb 24, 2019)

tron said:


> Jack I find the weight of 400 DO very useful in portability but at the same time its short length makes me holding it much more comfortable. My left hand does not get tired since I do not extend it much and it stays close to body (which also helps in stability). At the same time the 400 can be put in very reasonably sized bags. Add it's superb IQ and it is my favorite excursion lens.


Because of its short length, I can pack it into a 35x15x30 cm^3 backpack camera case with a body, extenders, charger, spare batteries etc and carry it onto a BA flight as an additional piece of hand luggage along with a larger cabin-sized case.


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## Joules (Feb 24, 2019)

tron said:


> These are BS! The current 400mm DO f/4 IS has 22cm length not ... 33!
> I do have it and it is exceptional! Why should I be so stupid to update it with a model 50% longer???


If the reduction in diameter that MT Spokane mentioned isn't tiny, it will have a far greater impact on volume and therefore on weight and material cost than a reduced length.

Keep in mind that in the volume of a cylinder, the radius factors in squared. Assuming a lens would be a solid chunk of material throughout, doubling the length doubles the weight, but cutting the radius in half reduces the weight to a quarter.

Just for fun, a rough comparision between the EF 300mm 2.8 IS II and the 300mm 4.0 IS. The difference in diameter is 128/90 = 1.42, which squared is 2. And that's pretty exactly the weight difference between them (2400g / 1190g). Those number are from the wikipage for the 300mm Canon lenses.

But lenses aren't solid. The length should have basically nothing to do with the weight, it just influences the center of mass maybe. So reducing diameter at the cost of length makes a ton of sense for reducing weight and maybe using a smaller volume in glass, which could even help with cost.


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## tron (Feb 24, 2019)

I believe the front element diameter cannot be made smaller than what the laws of physics dictate though. It will have to be the same as before. Focal Length divided by f/stop ...


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## Joules (Feb 24, 2019)

tron said:


> I believe the front element diameter cannot be made smaller than what the laws of physics dictate though. It will have to be the same as before. Focal Length divided by f/stop ...


Yeah, that's true. Looking at the drawing in the patent, all three designs have two large lenses at the feont, followed by the DO Element and a bunch of comparatively small ones. But the weight of those two first elements will likely still be quite hefty.

The point remains, it might be a good deal lighter or maybe optically better than current models, or cheaper. Any of those could be a good tradeoff for a bit of extra length.


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## AlanF (Feb 24, 2019)

Joules said:


> If the reduction in diameter that MT Spokane mentioned isn't tiny, it will have a far greater impact on volume and therefore on weight and material cost than a reduced length.
> 
> Keep in mind that in the volume of a cylinder, the radius factors in squared. Assuming a lens would be a solid chunk of material throughout, doubling the length doubles the weight, but cutting the radius in half reduces the weight to a quarter.
> 
> ...



The minimum diameter of a lens is determined by its f-number and its focal length. A 400mm f/4 has to have a diameter of at least 100mm at some point, plus some more to allow for the thickness of the mount. The current 400mm f/4 DO II has an overall diameter of 128mm and the diameter of the front element is just under 100mm, i.e. it is at the minimum diameter already.


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## AlanF (Feb 24, 2019)

I had measured the diameter of the DO II and found only 95mm. On checking the patent for the lens, I found the focal length is actually 392.12mm and the f-number 4.12, which squares with diameter.


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## Jack Douglas (Feb 24, 2019)

So we got gypped, no wonder my birds aren't as large as I expected, nor as bright or background blurred! When will Canon ever catch up .. oops, I think some other lenses are even worse.

Jack


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## tron (Feb 24, 2019)

AlanF said:


> Because of its short length, I can pack it into a 35x15x30 cm^3 backpack camera case with a body, extenders, charger, spare batteries etc and carry it onto a BA flight as an additional piece of hand luggage along with a larger cabin-sized case.


Wow! Alan this bag seems ultra compact. Can you tell us which model and make it is?


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## AlanF (Feb 25, 2019)

tron said:


> Wow! Alan this bag seems ultra compact. Can you tell us which model and make it is?


It's an old Tamrac - I looked at their website but can't find it as they seem to have just larger more complex ones now.


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## degos (Feb 25, 2019)

SwissFrank said:


> What was the last lens by anybody as jaw-dropping as the 28-70/2?



Sigma 105mm f/1.4



> Or the MTF bokeh etc. of the 1.2?



And more than THREE STOPS of vignetting at f/1.2... for $2500? Come on, that's just lazy lens design. "Sharper than the Sigma Art, ship it. Oh, triple the price too."


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## tron (Feb 25, 2019)

AlanF said:


> It's an old Tamrac - I looked at their website but can't find it as they seem to have just larger more complex ones now.


After my post I realised I use a manfrotto veloce V which is a terrible bag (almost everything is sewed instead of being able to be changed with velcro, the zipper gets damaged easily and it has no available strap for the waist) but it has more or less the same dimensions. It even holds a second body with lens...


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## AlanF (Feb 25, 2019)

tron said:


> After my post I realised I use a manfrotto veloce V which is a terrible bag (almost everything is sewed instead of being able to be changed with velcro, the zipper gets damaged easily and it has no available strap for the waist) but it has more or less the same dimensions. It even holds a second body with lens...


I checked the local camera store who had several bags of similar size, about 16L. I bought mine originally for the 100-400mm II, which fits inside with the body attached, but the DO I pack separate from the body.


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## Architect1776 (Feb 26, 2019)

Lurker said:


> Canon just bores me now, I don't expect them to do anything interesting for me ever again. Development announcements, Half baked and lower end cameras, just don't do it for me.
> 
> I'm much more interested in the 3rd party vendor news.



Let's see you use a lower end camera now, so your comments are interesting.
I guess the EOS lenses are not interesting because Canon was over 30 years ahead of all others and so when others introduce electronic diaphragms and everyone ohhs and ahhhs over it remember it is ancient technology.
The lens with a control ring as the RF has is again a huge deal that all others have nothing anywhere near like it. The Canon went further and destroyed others in innovation by making ALL your EF lenses have the same capability. The other major player abandoned half their Af system to obsolesce when they went mirrorless.
The R cameras are wonderful cameras and very solid workers. No Canon did not do the fluff that others have that either works half ass or is difficult to access.
If you think the R system is half baked then go elsewhere. But you will come back as the system matures in the next 2-3 years and the innovations in it are shown to be revolutionary and others will be trying to figure how to catch up.


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## Lurker (Feb 26, 2019)

Architect1776 said:


> Let's see you use a lower end camera now, so your comments are interesting.
> I guess the EOS lenses are not interesting because Canon was over 30 years ahead of all others and so when others introduce electronic diaphragms and everyone ohhs and ahhhs over it remember it is ancient technology.
> The lens with a control ring as the RF has is again a huge deal that all others have nothing anywhere near like it. The Canon went further and destroyed others in innovation by making ALL your EF lenses have the same capability. The other major player abandoned half their Af system to obsolesce when they went mirrorless.
> The R cameras are wonderful cameras and very solid workers. No Canon did not do the fluff that others have that either works half ass or is difficult to access.
> If you think the R system is half baked then go elsewhere. But you will come back as the system matures in the next 2-3 years and the innovations in it are shown to be revolutionary and others will be trying to figure how to catch up.



Don't get your knickers in knot. Did you read my post or just get pithy (can I say pissy?) when you read something not positive about Canon and/or RF? What I said was "RF has some really great stuff and has a really bright future but I highly doubt it will play any role in my future."

The EOS R body was and still is half-baked, in my opinion. Sorry, if you don't like to hear it but it won't be a fully-baked camera until the firmware is updated and the full functionality of the body is enabled. Canon does what they do and they know more about marketing/sales than I do but for me, a consumer about to spend lots of money on camera gear, that was a mistake. I believe they should have been in a position to release a completed camera and they should have been able to do it months ago. If they had done that, RF may be relevant to me.

The RF as a system is still very immature. There are no macro, super telephoto, tilt-shift lenses. I was expecting them to announce the pending release of new lenses, not just the development of the lenses. Who wasn't already expecting them to be developing most of these lenses?

Besides the R system what has Canon released? Point and shoot, maybe a consumer DSLR or M. All fine cameras but these are not a direction I'm going with my kit so these announcements bore me. If they excite you I'm happy for you. Neither of is wrong, just different.

As for where the R will be in 2-3 years. I don't care, I assure you I won't me sniffing around lusting after the new technologies. RF is pretty much irrelevant to me at this point. I've spent my money and put it into EF. I won't be chasing technology for the sake of the technology. I doubt there will be anything I want to do in the next 10 years that my new kit won't be able to do for me. I do not have this same confidence in the RF system. Will it get there? Certainly.

Canon bores me because they have become slow and complacent, or just simply abandoned me and EF. They seem more interested in protecting than innovating, at least in the EF world. What would excite me is a release date for a new 7D and new DO telephotos (that I hope come in under $12,000). We know they had a 600 DO prototype years ago but still no real world product. I believe they could have produced a killer 7D III by now. I fear they put too much EF stuff on hold, or just quit EF development, in favor of RF.

Canon bores me because too much of the news lately is about what they will do for me in the future and not about what they are providing for me now.

Canon has done great things in the past and will continue to in the future but what they are doing now just bores me. Sorry, but that's the way it is. I can only get excited about things that will impact me.

Now go to your room and stay there until you can come out and play nice. Maybe you need a snack, I hear low blood sugar makes some people cranky.


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## Jack Douglas (Feb 27, 2019)

I know who's a bore and it's not Canon. But that's just me, hobbling along with my Canon gear so clueless as to be thinking it's satisfactory. I guess ignorance is bliss.

Jack


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## Lurker (Feb 27, 2019)

Jack Douglas said:


> I know who's a bore and it's not Canon. But that's just me, hobbling along with my Canon gear so clueless as to be thinking it's satisfactory. I guess ignorance is bliss.
> 
> Jack


Zen master. I hope to attain your level some time. (Probably after I get a 600mm )


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## Jack Douglas (Feb 27, 2019)

Anyone hoping to attain my level is in for a rude surprise! My gear far exceeds my capability and perhaps that explains why I love it.

Jack


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