100-400 L IS vs. 70-300 IS (non-L): Are my results typical?

Started Jul 8, 2012 | Discussions thread
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100-400 L IS vs. 70-300 IS (non-L): Are my results typical?
Jul 8, 2012

Hi all. I have an upcoming vacation for which I'm deciding on which lenses to bring. I have both the Canon 100-400 f4.5-5.6 L IS and the 70-300 f4-5.6 IS (non-L). I'd like to take the lighter 70-300 but was concerned about image quality, so I compared the two lens using a resolution chart. The results were...not what I expected. In short, at both 100mm and 300mm, the 70-300 is clearly better. I posted the 300mm shots below (taken with Canon 20D, auto-focused, 300mm @ f8, mirror lockup, camera on tripod, IS off, no post-sharpening).

I purchased my 100-400 way back in '99, so it's one of the earlier ones, but I did send it into Canon in '06 for calibration, so I would think it would be as good as it can be. I even tried shooting with IS on to see if that would help, but it didn't improve.

So...I have to ask for those of you who have/had both lenses, is the 70-300 really better than the 100-400, or is my 100-400 basically a bad copy? How easy could the 100-400 be knocked out of alignment and need recalibration (even though I handle my lenses carefully)?

I did a search for other comparisons between these two lenses, but didn't come up with anything.

Thanks for any help!

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