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Samir Kharusi | all galleries >> Galleries >> Testing Canon Tele Extenders > 400mm vs 200mm+2x
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24 Nov 2006 Samir Kharusi

400mm vs 200mm+2x

Azaiba, Muscat

Click "original" below right to see the crops at 1:1. Used the Angle Finder C at 2.5x magnification and Viewscreen I (clear center with cross-hairs) for manual focus with the 200mm+2x. I compared my performance against autofocus, 5 frames in each mode. 4 autofocused frames looked very much equivalent, with one distinctly less sharp. 4 manual focus frames looked lousy, with the best one almost on par with the autofocused frames. Autofocus wins hands down! So issues seen earlier (previous slide) were not caused by the autofocus misbehaving. After much testing I concluded that they were caused by seeing (atmospheric shimmer). Consequently I had to use a target that was much closer for any further testing. The above target is between 200 and 250ft away (70m). I autofocused, center spot only on the vertical edge. To capture the frames with the frame-edge crops I simply panned the tripod without changing focus. Overall conclusions? The 200mm+2x is an excellent daytime combo closed down 2 stops to f11, still quite useful in these days of a competent ISO 1600, and I can use the 400mm/5.6L wide open for astrophotography, autofocused on any bright star or planet, whenever I need a focal length around 400mm. Next slide shows an example astrophoto.

Canon EOS 1Ds ,200mm/2.8L II + 2x II, 400mm/5.6L
All autofocused, center spot only full exif

other sizes: small medium large original auto
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