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    <title>topic Re: Teleconverter Pros and Cons in EF &amp; RF Lenses</title>
    <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196878#M7878</link>
    <description>&lt;P&gt;A word of warning. &amp;nbsp;Even a 600mm lens is not going to make a tiny bird, ... large! &amp;nbsp;Even with a 600mm lens you need to be very close to the bird. &amp;nbsp;Generally under 50 feet.&amp;nbsp;&lt;/P&gt;</description>
    <pubDate>Sat, 07 Jan 2017 12:20:25 GMT</pubDate>
    <dc:creator>ebiggs1</dc:creator>
    <dc:date>2017-01-07T12:20:25Z</dc:date>
    <item>
      <title>Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196823#M7872</link>
      <description>&lt;P&gt;I have a Canon Eos 80D and a Canon 100 - 400 mm F4.5 - 5.6 L IS USM lens and use them mostly for bird photography.&amp;nbsp; I think the 400 mm is not enough to capture small birds that tend to be skittish of humans.&amp;nbsp; Admittedly, I have lens envy when I see birds photographed with a 600 or 800 mm lens.&amp;nbsp; In generally, I really like the lens that I have but want to consider getting a teleconverter, at least a 1.4X.&amp;nbsp; I know about giving up an F stop but it's less clear to me about the effects of the teleconverter on focus points (I have 1, 9 and 45 on the camera) and on autofocus.&amp;nbsp; I would also like to know your thoughts on the pros and particularly the cons of using one.&amp;nbsp; Appreciate your feedback but if I'm asking a question that's already been asked, please let me know and I'll try to find the discussion.&amp;nbsp; Thanks.&lt;/P&gt;</description>
      <pubDate>Fri, 06 Jan 2017 19:05:17 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196823#M7872</guid>
      <dc:creator>mjschocken</dc:creator>
      <dc:date>2017-01-06T19:05:17Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196825#M7873</link>
      <description>&lt;BLOCKQUOTE&gt;&lt;HR /&gt;&lt;a href="https://community.usa.canon.com/t5/user/viewprofilepage/user-id/86833"&gt;@mjschocken&lt;/a&gt; wrote:&lt;BR /&gt;&lt;P&gt;I have a Canon Eos 80D and a Canon 100 - 400 mm F4.5 - 5.6 L IS USM lens and use them mostly for bird photography.&amp;nbsp; I think the 400 mm is not enough to capture small birds that tend to be skittish of humans.&amp;nbsp; Admittedly, I have lens envy when I see birds photographed with a 600 or 800 mm lens.&amp;nbsp; In generally, I really like the lens that I have but want to consider getting a teleconverter, at least a 1.4X.&amp;nbsp;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;I know about giving up an F stop but it's less clear to me about the effects of the teleconverter on focus points (I have 1, 9 and 45 on the camera) and on autofocus.&amp;nbsp; I would also like to know your thoughts on the pros and particularly the cons of using one.&amp;nbsp; Appreciate your feedback but if I'm asking a question that's already been asked, please let me know and I'll try to find the discussion.&amp;nbsp; Thanks.&lt;/P&gt;&lt;HR /&gt;&lt;/BLOCKQUOTE&gt;&lt;P&gt;&lt;BR /&gt;Use just the center AF point.&amp;nbsp; I'm pretty sure that&amp;nbsp;the center AF point in the 80D can focus to f/8.&amp;nbsp; I would strongly advise only using a Canon teleconverter, though, if any.&amp;nbsp;.&amp;nbsp;&lt;BR /&gt;&lt;BR /&gt;Image quality with the 1.4x is a whole other conversation. &amp;nbsp;The 150-600mm lenses out there are pretty popular.&lt;/P&gt;</description>
      <pubDate>Fri, 06 Jan 2017 19:22:51 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196825#M7873</guid>
      <dc:creator>Waddizzle</dc:creator>
      <dc:date>2017-01-06T19:22:51Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196833#M7874</link>
      <description>&lt;P&gt;Remember that your 80D is a so-called "crop camera" with a 1.6x crop ratio.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;So, if you are looking at photos taken with a Canon 1D X&amp;nbsp;or a 5D, which are popular professional birding cameras, with a 600mm lens, you will get the same effective view (actually a liitle more) with your 80D and a 400mm lens. (400*1.6=640).&lt;/P&gt;</description>
      <pubDate>Fri, 06 Jan 2017 21:06:38 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196833#M7874</guid>
      <dc:creator>jrhoffman75</dc:creator>
      <dc:date>2017-01-06T21:06:38Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196853#M7875</link>
      <description>&lt;P&gt;You may get by with stationary birds but will have lots of trouble (slow to no AF lock) on birds in flight. Highly recommend considering a 150-600 C from Sigma or maybe the newer version Tamron has out now. It's a lot of magnification on a crop body.&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 00:33:29 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196853#M7875</guid>
      <dc:creator>cicopo</dc:creator>
      <dc:date>2017-01-07T00:33:29Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196858#M7876</link>
      <description>&lt;P&gt;Thanks for these comments.&amp;nbsp; I do want BIF so I guess I need to start thinking about the Sigma 150 - 600 which I have seen images from.&amp;nbsp; Those that have it seem to like it.&amp;nbsp; It seems like an affordable solution for me.&amp;nbsp;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 01:54:52 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196858#M7876</guid>
      <dc:creator>mjschocken</dc:creator>
      <dc:date>2017-01-07T01:54:52Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196877#M7877</link>
      <description>&lt;P&gt;&lt;EM&gt;"...&amp;nbsp;recommend considering a 150-600 C from Sigma or ...&amp;nbsp;the newer version Tamron ..."&lt;/EM&gt;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;SPAN&gt;This is the correct answer. &amp;nbsp;&lt;img id="smileyhappy" class="emoticon emoticon-smileyhappy" src="https://community.usa.canon.com/i/smilies/16x16_smiley-happy.png" alt="Smiley Happy" title="Smiley Happy" /&gt; &amp;nbsp;Your choice. &amp;nbsp;They are nearly identical in IQ. &amp;nbsp;Either will work well on an 80D.&lt;/SPAN&gt;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 12:16:05 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196877#M7877</guid>
      <dc:creator>ebiggs1</dc:creator>
      <dc:date>2017-01-07T12:16:05Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196878#M7878</link>
      <description>&lt;P&gt;A word of warning. &amp;nbsp;Even a 600mm lens is not going to make a tiny bird, ... large! &amp;nbsp;Even with a 600mm lens you need to be very close to the bird. &amp;nbsp;Generally under 50 feet.&amp;nbsp;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 12:20:25 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196878#M7878</guid>
      <dc:creator>ebiggs1</dc:creator>
      <dc:date>2017-01-07T12:20:25Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196880#M7879</link>
      <description>&lt;P&gt;Deleted&lt;/P&gt;</description>
      <pubDate>Fri, 24 Feb 2017 17:29:58 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196880#M7879</guid>
      <dc:creator>TTMartin</dc:creator>
      <dc:date>2017-02-24T17:29:58Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196883#M7880</link>
      <description>&lt;P&gt;Thanks much for your comments and for an illustrative image with the lens and extender.&amp;nbsp; You've told me everything I wanted to hear as I do have the second, more recent version of the Canon telephoto zoom lens.&amp;nbsp; I also know a few guys who have the Sigma 150 - 600 mm lens and so I was also interested in your comments about the Canon versus Sigma/Tamron lens and their image quality.&amp;nbsp; Again, thanks.&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 13:24:26 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196883#M7880</guid>
      <dc:creator>mjschocken</dc:creator>
      <dc:date>2017-01-07T13:24:26Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196885#M7881</link>
      <description>&lt;P&gt;&lt;EM&gt;"The EF 100-400 L IS II with the 1.4X III extender still bests the image quality of the Sigma or Tamron 150-600s."&lt;/EM&gt;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;SPAN&gt;Of course this is wrong. &amp;nbsp;Even if you take published data on the three lenses mentioned, they are &lt;STRONG&gt;nearly identical&lt;/STRONG&gt;&amp;nbsp;in IQ. &amp;nbsp;Actually owning and using all three confirms it. &amp;nbsp;Adding a teleconverter to any one of them vs one without one, will degrade its IQ.&lt;/SPAN&gt;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 13:47:00 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196885#M7881</guid>
      <dc:creator>ebiggs1</dc:creator>
      <dc:date>2017-01-07T13:47:00Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196888#M7882</link>
      <description>&lt;BLOCKQUOTE&gt;&lt;HR /&gt;&lt;a href="https://community.usa.canon.com/t5/user/viewprofilepage/user-id/3485"&gt;@ebiggs1&lt;/a&gt; wrote:&lt;BR /&gt;&lt;P&gt;&lt;EM&gt;"The EF 100-400 L IS II with the 1.4X III extender still bests the image quality of the Sigma or Tamron 150-600s."&lt;/EM&gt;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;SPAN&gt;Of course this is wrong. &amp;nbsp;Even if you take published data on the three lenses mentioned, they are &lt;STRONG&gt;nearly identical&lt;/STRONG&gt;&amp;nbsp;in IQ. &amp;nbsp;Actually owning and using all three confirms it. &amp;nbsp;Adding a teleconverter to any one of them vs one without one, will degrade its IQ.&lt;/SPAN&gt;&lt;/P&gt;&lt;HR /&gt;&lt;/BLOCKQUOTE&gt;&lt;P&gt;Your statement that they all have nearly identical image quality is false. The Tamron lags the other lenses in the group. That has been shown by a number of testing and comparison sites. And the used market for those lenses is the biggest indicator of that. The Tamron 150-600 now sells on the used market for well under a thousand dollars, and only about a $100 more than the Sigma 150-500 OS that you've often maligned here.&amp;nbsp;&lt;BR /&gt;&lt;BR /&gt;All of the testing and comprison sites confirm that the&amp;nbsp;&lt;EM&gt;EF 100-400 L IS II with the 1.4X III extender still bests the image quality of the Sigma or Tamron 150-600s.&lt;/EM&gt;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;EM&gt;The easiest way to see for yourself is at &lt;FONT color="#0000FF"&gt;&lt;U&gt;&lt;A href="http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=929&amp;amp;Camera=453&amp;amp;Sample=0&amp;amp;FLI=5&amp;amp;API=2&amp;amp;LensComp=972&amp;amp;CameraComp=453&amp;amp;SampleComp=0&amp;amp;FLIComp=5&amp;amp;APIComp=2" target="_self"&gt;the-digital-picture.com&lt;/A&gt;&lt;/U&gt;&lt;/FONT&gt;&amp;nbsp;That's at 600mm stopped down to f/8 on the Tamron, and roll over to see the Canon at 560mm f/8 at the center there isn't much difference, but, by the time you get to the corners it is clear that the Canon has superior image quality..&lt;/EM&gt;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 17:16:53 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196888#M7882</guid>
      <dc:creator>TTMartin</dc:creator>
      <dc:date>2017-01-07T17:16:53Z</dc:date>
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      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196900#M7883</link>
      <description>&lt;P&gt;Deleted&lt;/P&gt;</description>
      <pubDate>Fri, 24 Feb 2017 17:30:54 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196900#M7883</guid>
      <dc:creator>TTMartin</dc:creator>
      <dc:date>2017-02-24T17:30:54Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196928#M7884</link>
      <description>&lt;P&gt;Nice Shot, TTMartin. 8^) Mine was taken in the Rio Grande Bosque with my Tamron 150-600.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;IMG src="https://community.usa.canon.com/t5/image/serverpage/image-id/12208i8DBBE3CC91B436D6/image-size/original?v=v2&amp;amp;px=-1" border="0" alt="IMG_1011.jpg" title="IMG_1011.jpg" /&gt;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 16:57:34 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196928#M7884</guid>
      <dc:creator>kvbarkley</dc:creator>
      <dc:date>2017-01-07T16:57:34Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196934#M7885</link>
      <description>&lt;BLOCKQUOTE&gt;&lt;HR /&gt;&lt;a href="https://community.usa.canon.com/t5/user/viewprofilepage/user-id/74913"&gt;@kvbarkley&lt;/a&gt; wrote:&lt;BR /&gt;&lt;P&gt;Nice Shot, TTMartin. 8^) Mine was taken in the Rio Grande Bosque with my Tamron 150-600.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;HR /&gt;&lt;/BLOCKQUOTE&gt;&lt;P&gt;Watching and hearing a Sand Hill Crane in flight is an experience straight out of Jurassic&amp;nbsp;Park. &amp;nbsp;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 17:07:57 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196934#M7885</guid>
      <dc:creator>TTMartin</dc:creator>
      <dc:date>2017-01-07T17:07:57Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196935#M7886</link>
      <description>&lt;P&gt;Yes, It was amazing. This was taken during the migration. There were dozens&amp;nbsp;milling around and flying where I was.&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 17:11:53 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196935#M7886</guid>
      <dc:creator>kvbarkley</dc:creator>
      <dc:date>2017-01-07T17:11:53Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196937#M7887</link>
      <description>&lt;P&gt;Too bad you don't spend more time doing and less time reading. &amp;nbsp;You would learn a lot more. &amp;nbsp;But to each his own, I guess.&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 17:21:28 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196937#M7887</guid>
      <dc:creator>ebiggs1</dc:creator>
      <dc:date>2017-01-07T17:21:28Z</dc:date>
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    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196942#M7888</link>
      <description>&lt;P&gt;I've shot the Sigma 150-600 C all of last season &amp;amp; it has benched my 100-400 L IS Ver 1 which is quite sharp. I finally got a shot I've been after for the last 2 seasons because for once I decided to use the right shutter speed because I really wasn't after prop blur. I have come very close at getting this result at 1/500 a few times but I think this confirms that the Sigma is sharp enough for most hand holders. Wing span is 88 inches &amp;amp; it's flying right to left doing rolls, I've turned it for the crop. (note slight prop blur even at this setting so likely at full power). First the full frame then a crop to the autographs of the Snowbird pilots 3 years ago &amp;amp; ISS Commander&amp;nbsp; Chris Hadfield.&amp;nbsp; Shot hand held with a 1D mark 4, Sigma 150-600 C @468 mm, f 6.3, 1/2000. At the end of the season I started shooting that lens on my 7D2 with excellent results &amp;amp; I plan on using it together next year along with the Canon 28-300 L IS on the 1D4.&lt;/P&gt;&lt;P&gt;&lt;IMG src="https://community.usa.canon.com/t5/image/serverpage/image-id/12209i5EE31802F3BF533E/image-size/original?v=v2&amp;amp;px=-1" border="0" alt="INGR8977v1.jpg" title="INGR8977v1.jpg" /&gt;&lt;IMG src="https://community.usa.canon.com/t5/image/serverpage/image-id/12210i82B1169F8AFC6BAF/image-size/original?v=v2&amp;amp;px=-1" border="0" alt="INGR8977v1-001.jpg" title="INGR8977v1-001.jpg" /&gt;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 17:31:57 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196942#M7888</guid>
      <dc:creator>cicopo</dc:creator>
      <dc:date>2017-01-07T17:31:57Z</dc:date>
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      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196969#M7889</link>
      <description>&lt;P&gt;Look and decide for yourself.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;[&lt;FONT color="#FF0000"&gt;Removed link per Forum Guidelines&lt;/FONT&gt;]&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;Compared to the 100-400 II with 1.4X III teleconverter, it's fairly obvious ...&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;- Tamron 150-600mm G2 is pretty equal at the center, but slightly softer away from the center at 500mm, and more-so at 600mm.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;- Original 150-600mm is softer away from the center at both 500mm and expecially at 600mm.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;All the comparisons I did were on full frame (1DSIII) and "wide open" in all cases (that means effective f/8 on the 100-400 + 1.4X and 1/3 stop faster f/6.3 on the Tamron lenses). The selectable focal lengths are slightly different, too... 560mm for the 100-400 + 1.4X versus 500mm and 600mm with the Tamrons.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;I'll leave it to you to compare other settings or the comparable Sigma lenses, if you wish. If you do so, just be sure to select the same camera body for the comparisons. It doesn't really matter which camera, so long as the same one is being used for both the lenses in the comparison.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;Compared to the Tamrons, while the center on all of them seem pretty similar, it looks to me as if the 100-400mm II with 1.4X is slightly superior in the corners and at the edges... on a full frame camera. Using any of these lenses on crop sensor cameras, the difference would probably be pretty hard to see.&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;I've got the 100-400mm II... but haven't had chance to try it with 1.4X yet. Using it on APS-C cameras (7DII), I just haven't needed any more than 400mm yet. Not sure if it will work as well with the 1.4X II that I have, as it appears to with the 1.4X III.&amp;nbsp;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;***********&lt;/P&gt;&lt;P&gt;&lt;BR /&gt;Alan Myers&lt;BR /&gt;San Jose, Calif., USA&lt;BR /&gt;"Walk softly and carry a big lens."&lt;BR /&gt;&lt;A href="http://photography-on-the.net/forum/showpost.php?p=4185712&amp;amp;postcount=838&amp;quot;]GEAR" target="_blank"&gt;GEAR&lt;/A&gt;: 5DII, 7DII (x2), 7D(x2) some other cameras, various lenses &amp;amp; accessories&lt;BR /&gt;&lt;A href="http://www.flickr.com/photos/amfoto1" target="_blank"&gt;FLICKR&lt;/A&gt;&amp;nbsp;&amp;amp; &lt;A href="http://amfoto1.exposuremanager.com/" target="_blank"&gt;EXPOSUREMANAGER&lt;/A&gt;&amp;nbsp;&lt;/P&gt;</description>
      <pubDate>Sat, 07 Jan 2017 21:29:17 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/196969#M7889</guid>
      <dc:creator>amfoto1</dc:creator>
      <dc:date>2017-01-07T21:29:17Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/197038#M7890</link>
      <description>&lt;P&gt;&lt;EM&gt;"I've shot the Sigma 150-600 C all of last season &amp;amp; it has benched my 100-400 L IS Ver 1 ..."&lt;/EM&gt;&lt;/P&gt;&lt;P&gt;&amp;nbsp;&lt;/P&gt;&lt;P&gt;&lt;SPAN&gt;It does show that real world shooting and data from testing sites can be very different and misleading. &amp;nbsp;I own, or rented, and use all of the lenses mentioned in this thread. &amp;nbsp;For most people I still maintain there isn't a nickels worth of difference&amp;nbsp;between them.&lt;/SPAN&gt;&lt;/P&gt;&lt;P&gt;&lt;SPAN&gt;However, in the hands of certain people there can be quite a difference. &amp;nbsp;Also it depends&amp;nbsp;on how much cropping &amp;nbsp;is done or required. &amp;nbsp;For most people, they will see a degrading of the IQ with a teleconverter with any of them. &amp;nbsp;It is my belief and experience that a lens without a converter is better than one with it.&lt;/SPAN&gt;&lt;/P&gt;</description>
      <pubDate>Sun, 08 Jan 2017 17:57:17 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/197038#M7890</guid>
      <dc:creator>ebiggs1</dc:creator>
      <dc:date>2017-01-08T17:57:17Z</dc:date>
    </item>
    <item>
      <title>Re: Teleconverter Pros and Cons</title>
      <link>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/197053#M7891</link>
      <description>&lt;BLOCKQUOTE&gt;&lt;HR /&gt;&lt;a href="https://community.usa.canon.com/t5/user/viewprofilepage/user-id/86833"&gt;@mjschocken&lt;/a&gt; wrote:&lt;BR /&gt;&lt;P&gt;Thanks much for your comments and for an illustrative image with the lens and extender.&amp;nbsp; You've told me everything I wanted to hear as I do have the second, more recent version of the Canon telephoto zoom lens.&amp;nbsp; I also know a few guys who have the Sigma 150 - 600 mm lens and so I was also interested in your comments about the Canon versus Sigma/Tamron lens and their image quality.&amp;nbsp; Again, thanks.&lt;/P&gt;&lt;HR /&gt;&lt;/BLOCKQUOTE&gt;&lt;P&gt;I chose the Sigma 150-600mm "C" over the comparable Tamron for one reason.&amp;nbsp; Sigma dock.&amp;nbsp; If you take the time to carefully calibrate your lens, you will be rewarded with really great photos.&amp;nbsp;&lt;BR /&gt;&lt;BR /&gt;And, I do mean take the time when doing focus adjustments.&amp;nbsp; I spent about three weeks testing and re-testing until I came up with a consistent set of average results.&amp;nbsp; Much of that is due to the number of calibration points [16]&amp;nbsp;in the Sigma.&amp;nbsp; I finally found the best way to test it was outdoors, in bright sunlight, aiming at the lines of empty parking spaces in a large parking lot.&amp;nbsp; The lines of the parking&amp;nbsp;spaces offered a quick and dirty way&amp;nbsp;to measure distances accurately enough for the calibration testing.&lt;/P&gt;</description>
      <pubDate>Sun, 08 Jan 2017 23:22:05 GMT</pubDate>
      <guid>https://community.usa.canon.com/t5/EF-RF-Lenses/Teleconverter-Pros-and-Cons/m-p/197053#M7891</guid>
      <dc:creator>Waddizzle</dc:creator>
      <dc:date>2017-01-08T23:22:05Z</dc:date>
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