Patent: More diffractive optics super telephoto lenses

Canon Rumors Guy

EOS 1D MK II
Jul 20, 2010
7,410
235
Canada
www.canonrumors.com
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

Focal distance: 582.00mm
F number: 4.12
Half field angle:  2.13°
Image height: 21.64mm
Whole length of the lens: 394.25mm
BF: 62.79mm

Canon 400mm f/4 DO IS

Focal distance: 405.00mm
F number: 4.12
Half field angle: 3.06°
Image height: 21.64mm
Whole length of the lens: 330.16mm
BF: 50.46mm

Canon 800mm f/5.6 DO IS

Focal distance: 795.00mm
F number: 5.60
Half field angle: 1.56°
Image height: 21.64mm
Whole length of the lens: 490.24mm
BF: 105.13mm
Continue reading...
 

tron

EOS 5D SR
Nov 8, 2011
3,835
184
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

EOS 80D
Sep 26, 2017
151
110
Madison, WI
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?
 

Lurker

EOS 80D
Dec 8, 2012
147
15
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.
 

SwissFrank

EOS RP
Dec 9, 2018
200
64
Canon just bores me now, I don't expect them to do anything interesting for me ever again.
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.)
 

Mt Spokane Photography

I post too Much on Here!!
Mar 25, 2011
15,167
476
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
 
Reactions: Bahrd

Mt Spokane Photography

I post too Much on Here!!
Mar 25, 2011
15,167
476
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.
 

Lurker

EOS 80D
Dec 8, 2012
147
15
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.
 

Jack Douglas

CR for the Humour
Apr 10, 2013
5,872
455
Alberta, Canada
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
 

tron

EOS 5D SR
Nov 8, 2011
3,835
184
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!
 

Jack Douglas

CR for the Humour
Apr 10, 2013
5,872
455
Alberta, Canada
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
 

tron

EOS 5D SR
Nov 8, 2011
3,835
184
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

5DSR
Aug 16, 2012
4,739
1,296
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.
 

Joules

EOS 80D
Jul 16, 2017
132
53
Hamburg, Germany
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.
 
Reactions: Jack Douglas

tron

EOS 5D SR
Nov 8, 2011
3,835
184
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 ...
 
Reactions: AlanF

Joules

EOS 80D
Jul 16, 2017
132
53
Hamburg, Germany
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.
 

AlanF

5DSR
Aug 16, 2012
4,739
1,296
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.
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.
 

AlanF

5DSR
Aug 16, 2012
4,739
1,296
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

CR for the Humour
Apr 10, 2013
5,872
455
Alberta, Canada
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