# Patent: Using Aluminum To Reduce Flare in DO Lens Elements



## Canon Rumors Guy (Apr 5, 2017)

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We continuously see new patents for diffractive optics lenses, something Canon continues to work and that we’ll see in a new <a href="http://www.canonrumors.com/canon-ef-600mm-f4-do-br-at-canon-expo/">EF 600mm f/4 DO IS</a> sometime in the future (Photokina 2018 perhaps?).</p>
<p>This <a href="http://pdfpiw.uspto.gov/.piw?PageNum=0&docid=09612372">latest patent</a> selectively uses aluminum to reduce light scattering or flare in diffractive lens elements.</p>
<p><a href="http://www.northlight-images.co.uk/canon-ef-lenses-rumours-and-news/">Keith at Northlight Images</a>, who is far better at reading patents than I explains:</p>
<blockquote><p>Aluminium is deposited onto the diffractive element at an angle, so as to build up a denser layer on the grating walls (blue) than the front surface (yellow). The aluminium layer is then partially oxidised, converting the front surface coating to a transparent layer of alumina (Al2O3)</p>
<p>Light going (‘the wrong way’) through the grating walls is a major contributor to flare, and in the patent, a test example reduced this by 8 times.</p></blockquote>
<p>While we can only confirm that an EF 600mm f/4 DO IS is coming, thanks to Canon showing off an early prototype at Canon EXPO 2015, we have had suggestions that multiple DO lenses may be announced in the coming years, and not just in supertelephoto applications.</p>
<p><em>image credit // <a href="https://www.focus-numerique.com/news/entretien-avec-mm-okada-hayakawa-et-izuki-de-canon-19731.html">focus numerique</a></em></p>
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## Chaitanya (Apr 5, 2017)

So if this patent is implemented it would be 3rd generation of DO lenses. Also I was told that 400mm DO was serious improvement over 1st gen lens.
On a side note: That prototype lens proves why I said that 600mm DO is going to be the most awkward lens to carry in bag.


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## NancyP (Apr 5, 2017)

Less awkward than the current bazooka. The real question should be - will it fit (be allowed in) carry-on luggage.


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## tron (Apr 5, 2017)

Chaitanya said:


> So if this patent is implemented it would be 3rd generation of DO lenses. Also I was told that 400mm DO was serious improvement over 1st gen lens.
> On a side note: That prototype lens proves why I said that 600mm DO is going to be the most awkward lens to carry in bag.


Yes, I do have the version II and it is very good but for situations against the sun. In every other case the result is similar to the results from the other big white lenses...


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## tron (Apr 5, 2017)

NancyP said:


> Less awkward than the current bazooka. The real question should be - will it fit (be allowed in) carry-on luggage.


Exactly! It will be ackward but at least it will fit in...


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## padam (Apr 5, 2017)

There is a patent for an EF 70-200/2.8 DO lens, I wonder if this technology will come to that as well or they will reserve it to the super-telephoto primes.


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## Mt Spokane Photography (Apr 6, 2017)

Canon seems to have some very active researchers in the construction of DO lenses. Many of their patents are impractical to mass manufacturer because of poor yield. However, its almost certain that some of the technologies can be made and will appear in new lenses. The processes seem pretty exotic, which means high prices. It would be great if they could succeed in churning out mass produced lenses, made by the millions for popular prices, but probably not in my lifetime.


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## Antono Refa (Apr 8, 2017)

Mt Spokane Photography said:


> The processes seem pretty exotic, which means high prices. It would be great if they could succeed in churning out mass produced lenses, made by the millions for popular prices, but probably not in my lifetime.



Does Canon sell millions of superteles?

I'll be surprised if even the 70-300mm DO sells that well. I've seen about as many copies of that one as I've seen of the EF 20-35mm or EF 28-70mm f/2.8-4


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## Light Sculptor (Apr 8, 2017)

I really applaud what Canon are doing! I go on extreme wildlife photography expeditions in the arctic, often carrying immense amounts of gear, from boats to guns all on my back, and so the larger white lenses literally can't fit within the airline weight and size allowance, once the essentials to survive in the wilderness are packed.

The big problem is the likely high cost of the upcoming DO lenses. The only DO lens I have owned is the 400 mk 1 version. I really want to own the second, but it is just not feasible for me at the moment.

It is however much better that canon produce these lenses than not do it, and I want them to keep going! In time, even if that is ten years hence, then it is likely that the mark 2 version will become more affordable, and some time after that the 600mm DO!


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## jeffa4444 (Apr 12, 2017)

Canon are not alone in the field of metal coatings on glass to improve performance. The F35 lighting visor for pilots uses metal vapour coatings and the number of these layers can be in the hundreds but they are too costly for most applications. The process is a grating mask in their patent and will have very high tolerances which add cost so don't expect cheap lenses.


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