<div name="googleone_share_1" style="position:relative;z-index:5;float: right; /*margin: 70px 0 0 0;*/ top:70px; right:120px; width:0;"><g:plusone size="tall" count="1" href="http://www.canonrumors.com/?p=9335"></g:plusone></div><div id="fb_share_1" style="float: right; margin: 0 0px 0 10px;"><a name="fb_share" type="box_count" share_url="http://www.canonrumors.com/?p=9335" href="http://www.facebook.com/sharer.php">Share</a></div><div><script src="http://static.ak.fbcdn.net/connect.php/js/FB.Share" type="text/javascript"></script></div><div class="tweetmeme_button" style="float: right; margin-left: 10px; margin-bottom: 70px;"><a class="tm_button" rel="&style=normal&b=2" href="http://www.canonrumors.com/?p=9335"></a></div>
<strong>Patent Time


</strong>A patent showing a new teleconverter has made an appearance. It appears to be a 2.7 or 2.8x TC. What effect woud it have on aperture? A 400 f/2.8L IS II would become 1120mm at f/8. All well and good, but the missing f/8 autofocus on the 1D X makes this one a bit strange with the current line of camera bodies.</p>
<p><strong>Patent Publication No. 2012-47869</strong></p>
<ul>
<li>2012.3.8 Release Date</li>
<li>2010.8.25 filing date</li>
</ul>
<p><strong>Example 1</strong></p>
<ul>
<li>-83.98mm focal length</li>
<li>Expansion rate β = 1.996</li>
<li>Lens Construction 5 group nine</li>
</ul>
<p><strong>Example 3</strong></p>
<ul>
<li>-41.91mm focal length</li>
<li>Expansion rate β = 2.779</li>
<li>Lens Construction 5 group nine</li>
</ul>
<p><strong>Canon’s patent</strong></p>
<ul>
<li>Rear converter is to increase the focal length, F number, the residual aberration</li>
<li>When doubled, twice the lateral aberration, longitudinal aberration is 4 times greater rate of expansion, because the F-number is also double, longitudinal aberration is twice per depth of focus</li>
<li>Rear converter configuration consisting of three groups of positive and negative positive</li>
<li>Reduce the aberration of the rear converter itself</li>
</ul>
<p><strong>Source: [<a href="http://egami.blog.so-net.ne.jp/2012-03-26" target="_blank">EG</a>]</strong></p>
<p><strong><span style="color: #ff0000;">c</span>r</strong></p>