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<p>That patent train continues for EF-M lens optical formulas, this time we see a 50-300mm f/4.5-5.6 DO lens for APS-C sized sensors. This optical formula patent shows the lens for both EF-M and EF-S mounts. It’s definitely interesting to see diffractive optics development for consumer grade cameras.</p>
<p>Patent Publication No. 2016-57444 (Google Translated)</p>
<ul>
<li>Published 2016.4.21</li>
<li>Filing date 2014.9.9</li>
</ul>
<p>Example 1</p>
<ul>
<li>Zoom ratio 5.59</li>
<li>Focal length 51.77 135.00 289.53</li>
<li>F-number 4.65 5.05 5.85</li>
<li>Half angle of view (degrees) 14.78 5.78 2.70</li>
<li>Image height 13.66 13.66 13.66</li>
<li>The total lens length 126.05 169.37 184.15</li>
<li>BF 35.50 35.50 35.50</li>
</ul>
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<p>Example 2</p>
<ul>
<li>Zoom ratio 5.90</li>
<li>Focal length 49.13 135.00 290.00</li>
<li>F-number 4.65 4.95 5.85</li>
<li>Half angle of view (degrees) 15.54 5.78 2.70</li>
<li>Image height 13.66 13.66 13.66</li>
<li>The total lens length 108.00 152.12 168.00</li>
<li>BF 15.69 15.69 15.69</li>
</ul>
<p>We have yet to see any full frame optical formulas for a full frame mirrorless camera body. We don’t find this surprising as we expect any such camera be compatible with EF lenses.</p>
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