# Patent: Canon 500mm f/4 DO IS and Canon 600mm f/4 DO IS



## Canon Rumors Guy (Jan 17, 2019)

> It seems patent applications for diffractive optic super telephoto lenses is becoming a monthly thing. Canon News has uncovered another patent application showing both a 500mm f/4 DO IS and a 600mm f/4 DO IS example.
> Canon showcased a 600mm f/4 DO IS at the Canon Expo back in 2015, and we haven’t really heard anything else about it since. There seems to be a lot of resources being put into DO lenses and yet we only have one available from Canon in the EF 400mm f/4 DO IS II.
> We predict that the RF mount will get some DO lenses in the future for the obvious reasons of size and weight reduction, which is especially important for a lot of super telephoto shooters.
> 
> ...



Continue reading...


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## Maximilian (Jan 17, 2019)

Interesting times 
I am curious how much they can shrink and slim down those "big" whites.
Seems to be just about 2cm each:

Length of the 600mm lens compared to existing EF+44mm flange: 474.74mm vs. 492mm
Length of the 500mm lens compared to existing EF+44mm flange: 409.74mm vs. 427mm


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## criscokkat (Jan 17, 2019)

Maximilian said:


> Interesting times
> I am curious how much they can shrink and slim down those "big" whites.
> Seems to be just about 2cm each:
> 
> ...



They've made a big deal about "straighter paths of light" with the new system that don't really seem to apply as much to long lenses. But maybe the DO lenses have less elements for a clearer and lighter system? 60MM is not really a huge difference, but if it's better image quality and slightly lighter It'll still sell to all the professionals. Even then 2.3 inches adds up if every lens in a professional's bad is that much smaller and lighter too.


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## Maximilian (Jan 17, 2019)

Hi criscokkat!



criscokkat said:


> 60MM is not really a huge difference...


Sorry but I don't get your 60 mm.

As I said, the overall optical formula (first element to sensor plane) is just about 2 cm (=20 mm) shorter.
As the flange distance between EF and RF (44mm-20mm) deliver a 22 mm LONGER lens barrel (like using the adapter) the difference is about NULL. 

Mechanically the lenses will have about the same length.


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## mb66energy (Jan 18, 2019)

While I usually do not like fake packaging (in german Mogelpackung) in this case it leads me to the conclusion that these lenses are more or less empty in terms of glass compared to the current non-DO iteration (see https://cweb.canon.jp/ef/lineup/super-tele/ef500-f4l-is-ii/spec.html and scroll down to the cut view).
This might lead to the conclusion that the patented lens design can be substantially lighter than the current design - and maybe substantially cheaper.
If they can shave off 20% of the price they are close to Sigma's 500mm lens (7000 EUR for the Canon vs. 5900 for the Sigma) - but I think roughly 100% of Canon users would prefer the Canon in that case.


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## degos (Jan 18, 2019)

Well now I don't feel so bad for not being able to afford the 600mm f4 III, I'll just keep saving for the DO!

> and yet we only have one available from Canon in the EF 400mm f/4 DO IS II.

No, the horrid 70-300 DO is still in the catalogue, 15 years after introduction:

https://www.usa.canon.com/internet/...elephoto-zoom/ef-70-300mm-f-4-5-5-6-do-is-usm


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## GMCPhotographics (Jan 18, 2019)

I'm a long time user of the ef 400mm f2.8 LIS (mkI). It's an astonishing optic, but it is also astonishingly heavy. I felt that the mkII was a huge improvement in weight compared to the mkI...but not enough to justify the eye watering cost. So I've been waiting for the mkIII and for it's price to drop a bit. The mkII launched at nearly £12K UKP so the new mkIII's price is very similar. The mkIII's weight is far more manageable and as long as the image quality is in the same league...then I might be tempted to replace my mkI when the price drops a bit. By that time the DO version will have launched and the mkIII's price will discount a bit more too.


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## GMCPhotographics (Jan 18, 2019)

Maximilian said:


> Hi criscokkat!
> 
> 
> Sorry but I don't get your 60 mm.
> ...



The lack of a mirror box offers little benefits with longer lenses. Anything over 50mm will have generally be the same size as it's SLR equivalent. SLR wide lenses generally have been employing a retro-focus design to allow the mirror box space in the lens design. A Mirror less camera doesn't have the requirement so the wide lenses (roughly anything under 50mm) don't require a retro-focus design so they can be a lot smaller, lighter and with less internal vignetting or light fall off. Mirror less formats aren't a magic bullet that make every lens shorter....it's not a crop format. I can see little benefits for a 400/500/600mm lens on a Mirror less format. So I wonder if Canon is very aware of this and will only release the "DO" range on the Eos R range...purely for marketing reasons. If you want a dedicated big while on an Eor R...you go DO, which will be lighter and smaller because of the DO design and not because of the mount it's attached too.


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## Maximilian (Jan 18, 2019)

Hi GMCPhotographics!



GMCPhotographics said:


> The lack of a mirror box offers little benefits with longer lenses. Anything over 50mm will have generally be the same size as it's SLR equivalent
> ...
> If you want a dedicated big while on an Eor R...you go DO, which will be lighter and smaller because of the DO design and not because of the mount it's attached too.


Thanks for pointing that out again. I was aware of that but maybe others not.

BUT....

As I showed with my posts and calculations above in this case/these patents the DO does NOT make the lenses mechanically any smaller and the optical formula is only about 2 cm smaller. And this is used up by the shorter flange distance.

So in this case maybe the lenses will become lighter with DO but certainly NOT shorter.


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## tron (Jan 18, 2019)

Maximilian said:


> Hi GMCPhotographics!
> 
> 
> Thanks for pointing that out again. I was aware of that but maybe others not.
> ...


The fact they are smaller is one reason that the DO lenses are lighter too. And Canon reduced the weight of 400 III and 600 III lenses a lot. If the new patents show a similar length to the non-DO lenses then they are of no use to shooters since version III lenses are much lighter already.


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## Nat_WA (Jan 18, 2019)

Possibly, similar to the new designs of other super tele's, the weight distribution is better as well; from the patent picture it seems most of the glass is positioned closer to the camera body. So advantage would (could) be

Slightly shorter overall length
Somewhat lighter
Center of gravity closer to the camera body, so easier to work with
Just speculating though... (and drooling over the thought of ever owning such a beast )
W.


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## Josh Leavitt (Jan 18, 2019)

I'd like them to take a stab at making a high-quality x10 zoom DO lens. To my mind, the EF 28-300mm F3.5-5.6L IS USM stands to benefit the most from the size and weight reduction of the DO technology. If they designed a new version of this lens as an RF 28-300mm F3.5-5.6L IS USM and replaced the push/pull zoom with a helicoid zoom, then I think it has a lot of sales potential as a go-to travel lens for the EOS R system. It would still be expensive - DO elements aren't cheap to make, and Canon would have to completely redesign the lens for RF mount optimization, but I'd expect the sales volume of such a lens to outsell 500 & 600 DO supertele lenses.


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## Mt Spokane Photography (Jan 18, 2019)

The patent seems to be more about weight than length reduction, here is a snippet from example one of the patent.

"Then, as for the optical system L0 of the present invention, the aperture-diaphragm S twist is also using lens constitution in pre-group LF on the object side as the positive lens GFP and the cemented lens which forms the diffraction optical element Ldoe. A lens effective diameter is small-diameter-ized and the weight saving of lens weight is attained because this takes the sufficiently wide interval on the optic axis of both lenses. And the focus lens group Lfo which is a moving lens group for focuses is also arranging an aperture-diaphragm S twist to the image side, it small-diameter-izes a lens effective diameter, also miniaturizes a mechanism mechanism in connection with it, and is attaining the weight saving of the whole system."

Multiple resin molded diffraction lenses cemented to glass lenses are used, thats expensive, and probably not likely to be used, the yield may be too low to afford two or more diffraction lenses.

The patent also states that the design is only practical for lenses with 4.5 degree FOV or less (>455mm), which makes a 500mm lens near the lower limit of practicality. I read this to mean that there is more benefit in a 600mm or longer lens.

"The imaging device described in Claim 10, wherein the maximum imaging half field angle is 4.5 degree or less."


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## tron (Jan 18, 2019)

The prototype 600mm DO f/4 lens was about 31 to 32cm long. Right now the 600mm f/4L IS III weighs 3.05Kg so it is probable that they will have diminishing returns in further weight reduction attempts. But going from the current 600mm length of 44 to 45cm to 31 to 32cm is a huge improvement.


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## [email protected] (Jan 18, 2019)

I wonder if the "resin molded ... lenses cemented to glass" is similar or same to the "Blue Goo." The blue refractive optics were innovative in that they appear to have unique refractive qualities (not as relevant to this new DO stuff) and also because they were essentially plastic bonded to glass. I wonder if that is the critical development; that weight can be saved by using plastic optical elements, and that DO structures can be more cheaply manufactured by simply molding plastics. If that speculation is true, there might be some real savings in making DO lenses.

Canon has always been cagey about describing its Blue Goo stuff as plastic, probably fearing negative reaction to the term. It does beg the question about whether or not such a lens element will remain perfectly clear and in shape 2 or 3 decades after manufacture. That said, if I were given an opportunity to buy a 500mm DO f/4 with plastic elements at $6000 that would last only 15 years in prime optical quality, I'd do it over purchasing a $9000, heavier glass one.


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## Maximilian (Jan 18, 2019)

tron said:


> ... But going from the current 600mm length of 44 to 45cm to 31 to 32cm is a huge improvement.


Such would surely be. 
But this size reduction is not part of THIS patent, as optical formula and therefore lens are much longer.


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## BurningPlatform (Jan 18, 2019)

As the back focus of both these designs is around 10 cm, there is no technical reason for these lenses to be built for RF mount only. They could as well be built for EF mount. They probably will not, however, but the reasons are purely commercial.


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