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I'm currently shooting a Canon 40D with a 70-200 2.8 lens with a 2Xteleconverter for an effective 400mm F5.6. Would I see any improvement switching to the Canon 100-400 L? Would I notice an improvement in image quality, but perhaps more importantly would focus time be improved? Will the 100-400 work with a 1.4X converter? I know it won't work my my current 2X. I borrowed the lens and tried it.Marv
The 100-400 will provide sharper results and faster AF than the 70-200 w/2x. The 100-400 will work with the 1.4x, although I do not recommend it. Moreover, your camera will not AF at f/8...100-400 f/5.6 w/1.4x =f/8
Best,
Chas
The 1-400L is an excellent all-around lens (user since July 2005). Results with the 1.4xTC are less than reliable. In good light with a slow/non-moving subjects it can provide good results (dependent of course on your definition of "good"). Taping the pins trick slows down the AF too much. There are non-reporting brands that will provide AF but I've not used them so can't provide comment. I did use a Kenko 300 Pro TC though and it caused my image to jump when the IS was on and the shutter button was pressed. I did not have that problem with the Canon 1.4xTCII.
Marvin,
I've had a 100-400 for more than a decade. In my opinion (and as seen in Canon's MTF charts) the images are soft at the long end. A 300 mm f/4 L IS will provide about the same detail as the 100-400 at 400. The 300 f/4 is smaller, lower cost, lighter and is a sealed lens (the 100-400 is not sealed). The 300 f/4 will work with a 1.4x TC on your 40D and you will still have AF.
Roger
Roger the 300 f/4 IS L is not weathersealed.
See this list for Canon's weather sealed lenses.
http://www.lensplay.com/lenses/lens_weathersealed.html
I think you meant the 300 f/2.8:)
Chris,
I meant that the 300 f/4 L is sealed from the body. If dust got in the lens, it would be very difficult for any dust to get into the body. The 300 f/4 L has internal focusing, so when you focus, there is no change in air that pushes air into the camera body. No "sealed" lens is perfectly sealed. The 100-400 is a different beast. When you zoom, the lens changes size and as it does that it draws air into the lens body or pushes it out. Hold the rear of the 100-400 up near your cheek, then zoom the lens in and out. Feel the air being pumped against your cheek. That air pumping action happens with the lens on the body, providing an easy pathway for dust to get into the camera body. It is that difference to which I was referring.
Roger
Depends on the copy of the 100-400. Canon has fixed or changed something either in the production or the QC of the lens (my speculation). I've used an older 100-400 and found the results to be mixed at 400mm. I have a newer (2008 production) 100-400 and its optically fantastic. With a recent copy of the 100-400 the difference at 400mm vs. the 70-200 with 2x TC should be quite dramatic.
if it's for birding ....i would suggest the 400 f/5.6 ...just bought one last week :)
