# EF 600 f/5.6 DO Patent



## Canon Rumors Guy (Nov 23, 2010)

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<strong>Weâ€™ve seen a 600 DO patents before, no lens yet.</strong>

<a href="http://photorumors.com/2010/11/22/canon-files-a-patent-for-a-600mm-f5-6-lens/#more-7020">PR</a> shows us a patent for a 600 f/5.6 DO lens. (JPO 2010-145832)</p>
<p><img class="aligncenter size-medium wp-image-5451" title="canon-600mm-f5.6-lens-patent" src="http://www.canonrumors.com/wp-content/uploads/2010/11/canon-600mm-f5.6-lens-patent-300x191.gif" alt="" width="300" height="191" /></p>
<p>Weâ€™ve seen <a href="http://www.canonrumors.com/2009/12/lens-patents-everywhere/">patents for DO lenses before</a>. There are 300mm, 400m and 600mm DO patents.</p>
<p>Take a <a href="http://www.canonrumors.com/category/photography/canon-patents/">peak at some of the other lens patents</a> Canon has filed. There was even one for a Zoom fisheye, though itâ€™s different than what actually reached market.</p>
<p><strong><span style="color: #ff0000;">c</span>r</strong>
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## scalesusa (Nov 23, 2010)

I think its just like pellicle mirrors, they are mentioned in several recent patents. Cannon is keeping their options open. 

I suspect that they have computers running night and day trying to discover new optical formulas that are sharper and producible. When they find a good one, they patent it to protect all the big bucks that went into searching for, and discovering it.


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## Justin (Nov 24, 2010)

Where does it announce it is a DO lens?


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## scalesusa (Nov 25, 2010)

Justin said:


> Where does it announce it is a DO lens?



PATENT ABSTRACTS OF JAPAN

(11)Publication number : 2010-145832 

(43)Date of publication of application : 01.07.2010 

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(51)Int.Cl. G02B 13/02 (2006.01)G02B 13/18 (2006.01)H04N 5/225 (2006.01)H04N 101/00 (2006.01)


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(21)Application number : 2008-324169 (71)Applicant : CANON INC

(22)Date of filing : 19.12.2008 (72)Inventor : SATO ARATA


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(54) PHOTOGRAPHING LENS, AND IMAGING APPARATUS WITH THE SAME

(57)Abstract:
PROBLEM TO BE SOLVED: To provide a compact photographing lens that is well corrected in an axial chromatic aberration and chromatic aberration of magnification.
SOLUTION: The photographing lens includes a pre-group L1 of positive refractive power, a diaphragm, and a post-group L2 of negative refractive power, from an object side to an image side in order. The pre-group L1 includes a diffractive optical element of positive power, and at least one negative lens constituting the post-group L2 includes an anomalous dispersion material, thereby setting the optical power of the diffractive optical element and the refractive power of a negative lens NL properly.


That term "Diffractive Optical Element" indicates a DO lens.


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