Quote Originally Posted by neuroanatomist





Wow
Quote Originally Posted by Kayaker72
I am pretty excited about the 70-300 mm f4.0-5.6 IS. I've been seriously considering buying the 70-200 mm f/4 IS. If the IQ is similar,the extra 100 mm for a few hundred dollars may be a bargin. And I was also looking at both extenders
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Keep in mind that you're getting 100mm but your losing a stop of light, going from f/4 to f/5.6. An f/5.6 apertureat the long end means if you add one of those new extenders (or an old one) to this new 70-300mm L, you will lose autofocus capability unless you have a 1-series body (and even a 1-series body will not AF with this new 70-300mm L + 2x Extender, since that will be f/11 at the long end).



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I definitely willbe looking at what range that is f/4 and what range is f/5.6.The70-300 Lis also 1 lb lighter than the 100-400, but ~0.75 lb heavier than the 70-200 f/4. It is short and somewhat stumpy, but, if I am readingthe MTF chartscorrectly, the optics should be very good (http://www.usa.canon.com/cusa/consumer/products/cameras/ef_lens_lineup/ef_70_300_f_4_5_6l_is_usm#Overview). I had been planning to get a 70-200 f/4 this year and then start saving for a 100-400....this could be a nice compromise.


I have a 7D, could you explain the extenders not working at certain apertures?
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