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<strong>Improved Canon ultrawide for full frame?
</strong>The world is waiting for Canon to release a top end performing ultra wide lens for full frame cameras. While I think the 17-40 f/4L is a bargain of a workhorse and the 16-35 f/2.8L II is a very solid performer, I think the line is still lacking that standout ultra wide zoom lens. I have heard numerous photographers say they’d pay “anything” for a top notch lens in that segment.</p>
<p>Below are 3 patented optical formulas for new ultrawide angle lenses for Canon.</p>
<p>A 16-35 f/2.8, a 17-35 f/2.8-4 and a 16-35 f/2-2.8. There seems to be a decent amount of f/2 patents appearing on zoom lenses from Canon, it could be time for such a lens to make it to market.</p>
<p><strong>Patent Publication No. 2012-63568</strong></p>
<ul>
<li>2012.3.29 Release Date</li>
<li>2010.9.16 filing date</li>
</ul>
<p><strong>Example 2</strong></p>
<ul>
<li>Zoom ratio 2.06</li>
<li>24.00 – - 33.95mm f = 16.48 focal length</li>
<li>Fno 2.90 – 2.90 – 2.91</li>
<li>42.03 – - 32.51deg 52.70 angle of view.</li>
<li>Image height 21.64mm</li>
<li>170.87 – - 172.62mm 178.10 full-length lens</li>
<li>BF 40.00 – 48.45 – 61.71mm</li>
<li>Lens Construction 12 group 17 sheets</li>
<li>Three three aspherical surface</li>
<li>2 UD lens sheet</li>
</ul>
<p><strong>Example 4</strong></p>
<ul>
<li>Zoom ratio 1.94</li>
<li>24.01 – - 33.98mm f = 17.51 focal length</li>
<li>Fno 2.91 – 3.21 – 3.86</li>
<li>Image height 21.64mm</li>
<li>174.18 – - 175.92mm 178.81 full-length lens</li>
<li>BF 41.60 – 48.49 – 60.70mm</li>
<li>Lens Construction 12 group 17 sheets</li>
<li>Three three aspherical surface</li>
<li>2 UD lens sheet</li>
</ul>
<p><strong>Example 6</strong></p>
<ol>
<li>Zoom ratio 2.06</li>
<li>24.02 – - 33.99mm f = 16.49 focal length</li>
<li>Fno 2.15 – 2.46 – 2.94</li>
<li>42.02 – - 32.48deg 52.69 angle of view.</li>
<li>Image height 21.64mm</li>
<li>171.08 – - 172.88mm 176.23 full-length lens</li>
<li>BF 39.26 – 46.99 58.75mm</li>
<li>18 sheets 13 group lens configuration</li>
<li>Three three aspherical surface</li>
<li>2 UD lens sheet</li>
</ol>
<p><strong>Canon’s patent</strong></p>
<ul>
<li>4-group zoom lens of a positive negative positive and negative</li>
<li>Inner Focus</li>
<li>Optimized so as to reduce the field curvature of the wide-angle side</li>
</ul>
<p><strong>Source: [<a href="http://egami.blog.so-net.ne.jp/2012-03-30" target="_blank">EG</a>]</strong></p>
<p><strong><span style="color: #ff0000;">c</span>r </strong></p>