dennis_tam Posted October 31, 2009 Share Posted October 31, 2009 <p>Hi,<br> I have a 40D body and want to shoot some birds.<br> I purchased canon extender 2X and coupled it with my 135mm 2L and 300mm 4L IS.<br> There is good picture quality on extender 2X/135mm 2L.<br> However, I can not even get auto focus on extender 2X/300mm 4L IS. Under manual focusing mode of 40D, the picture is quite blurry.<br> I checked the compatibilty table offered by Canon and they should be compatible to get AF.<br> Does any one have the same combination (extender 2X/300mm 4L IS) that I have? Is there anything I should specifically set on body/lens to get AF?<br> Thanks,<br> Dennis</p> Link to comment Share on other sites More sharing options...
shambrick007 Posted October 31, 2009 Share Posted October 31, 2009 <p>the combined f stop with the 2x on a f4 lens is f8. this means no auto focus on your 40d.</p> Link to comment Share on other sites More sharing options...
shambrick007 Posted October 31, 2009 Share Posted October 31, 2009 <p>the combined f stop with the 2x on a f4 lens is f8. this means no auto focus on your 40d.</p> Link to comment Share on other sites More sharing options...
sattler123 Posted October 31, 2009 Share Posted October 31, 2009 No AF with your 40D because the effective Aperture is now f/8 and the 40D will only AF up to f/5.6. You could get a non-Canon 2x extender (like the Kenko pro) and tape three pins and have AF in good light (but ONLY in good light) or just buy the 1.4x from Canon instead and your lens will focus just fine on your 40D. Link to comment Share on other sites More sharing options...
eric merrill Posted October 31, 2009 Share Posted October 31, 2009 <p>In my tests, the 1.4x with the 300/4 IS and then upsampling via Photoshop produced the same quality as using the 2x. Since the quality was the same and I lost autofocus, I stopped using the 2x with the 300/4.</p> <p>For whatever reason, the 2x with the 300/2.8 produces superior results than the 1.4x and upsampling. Not sure why, but that's my personal results. :)</p> <p>Eric</p> Link to comment Share on other sites More sharing options...
m._scott_clay1 Posted October 31, 2009 Share Posted October 31, 2009 <p>The 1D series will auto focus at f8. Used 1D MkII's have come way down in price.</p> Link to comment Share on other sites More sharing options...
philip_wilson Posted October 31, 2009 Share Posted October 31, 2009 <p>As Scott says only 1 series bodies have AF at F8 this does include the film bodies and the EOS 3. I do not use the f4 lens but use the F2.8. Even with the 300 F2.8 while you retain Af the 2x TC is not great. I did not buy the Mark I 2xTC but did get the MarkII although I almost never use it as it is very poor compared to the 1.4x TC. The 2X TC is especially bad on zooms like the 70-200 f2.8L</p> Link to comment Share on other sites More sharing options...
lester_wareham Posted October 31, 2009 Share Posted October 31, 2009 No it will only MF. However it can produce good sharpness with the 2X as long as you focus acuratly. In my tests using the 2X tc was always better than using a 1.4X and upscalling. http://www.zen20934.zen.co.uk/photography/LensTests/tc_comp/index.htm however these tests were with a 20D and it is possible that a higher resolution camera may be different, I'll have to check with my 7D. Of course MF for birds is not too practicle. Surprisingly double stacking the ef 1.4X with a kenko pro 1.4X worked well with the 300mm in good light and permits AF. Test for this are findable from the above link. Link to comment Share on other sites More sharing options...
isaac sibson Posted October 31, 2009 Share Posted October 31, 2009 <p>I bought the 2X II to use with my 300 F4L IS with my EOS 3 which would AF with it. </p> <p>I've never had a good result from it. I have had great results with the 1.4X, but never with the 2X. The same is true with the subsequent bodies I've tried it on (20D, 5D). The 2X sits gathering dust. </p> Link to comment Share on other sites More sharing options...
bobatkins Posted October 31, 2009 Share Posted October 31, 2009 <p>The 2x on the 300/4L is fine. Focus carefully and stop down a stop and you'll get decent (if not exceptional) results. Technique counts a lot when using the 2x. You may want to use Live View and 5x magnification for focus if your eye's aren't sharp enough.</p> <p> </p><div></div> Link to comment Share on other sites More sharing options...
keith reeder Posted October 31, 2009 Share Posted October 31, 2009 <blockquote> <p>You could get a non-Canon 2x extender (like the Kenko pro) and tape three pins and have AF in good light (but ONLY in good light)</p> </blockquote> <p>Probably not, Juergen<a href="../photodb/user?user_id=2071567"></a> - it's pretty well known that the 40D doesn't play well with taped or non-reporting TCs at f/8: my 40D won't work <em>at all</em> on the centre AF point with a 1.4x and 100-400mm at f/5.6 whereas the same set-up was great on my 30D.</p> <p>I know I'm far from alone here (much discussion about it since September 2007 - I think I might have been <a href="http://forums.dpreview.com/forums/read.asp?forum=1019&message=24792272">the first to publicise this fact</a> ) and while odd 40Ds seem to work, more or less, the majority of folk who have contributed to discussions about it report similar lack of success.</p> <p>A 300mm f/4 and a 2X will likely be exactly the same.</p> Link to comment Share on other sites More sharing options...
mirek_elsner1 Posted November 1, 2009 Share Posted November 1, 2009 <p>Just in case you want to consider Canon 1.4x extender - it works well with this lens, but the AF slows down considerably.</p> Link to comment Share on other sites More sharing options...
PuppyDigs Posted November 1, 2009 Share Posted November 1, 2009 <p>Nice moon portrait Bob!</p> <p>Well, LV 5X for MF probably will be a bit slow for birding. My old EOS 3 would AF with an F8 lens, but only with the center AF point and in single axis mode. I tried it with my 300 4L and Extender 2x and found it pretty iffy for anything but landscapes. Didn't shoot the moon tho'</p> Sometimes the light’s all shining on me. Other times I can barely see. - Robert Hunter Link to comment Share on other sites More sharing options...
dennis_tam Posted November 1, 2009 Author Share Posted November 1, 2009 <p>Thanks a lot to everybody!<br> I can still live with extender 2X/135mm 2L, which gives me 270mm, equivalently. Yes, I can get extender 1.4X later.<br> Dennis</p> Link to comment Share on other sites More sharing options...
jamie_robertson2 Posted November 2, 2009 Share Posted November 2, 2009 <p>I also own the 300mm f4L and the 1.4x. It is a fantastic combination. I don't find that the AF slows down that much, only slightly. I used to own the 2x but I sold it after two weeks. It was not worth using. The 1.4x is far superior.</p> Link to comment Share on other sites More sharing options...
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