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Canon 28-70mm f2.8L

Tested with a Canon EOS 5D

One of the reasons I’m making all these tests is to fill in the gaps that other test reports have eluded to rather than actually covered in detail. So the end of this test is going to be slightly different from normal. There is no question to me that this lens and the 5D are both superb individually. The really interesting part is in how they work together.

Canon have pioneered useable full frame sensors which give us back wide angles lenses - This should make lots of existing lenses much more useful again, but the 5D produces different results from film with the same lenses. What is particularly noticeable in the tests is a loss of sharpness away from the centre at wide apertures. More than I would expect with either of the lenses I’ve tested so far. I think this has more to do with the camera than the lenses. For that reason I’ve made a 5D image quality page give you some idea of what I’m finding.

Canon EOS 5D Image quality

Darkening in the corners at full aperture

Conclusions

All of my concerns over vignetting and corner sharpness don’t mean this lens isn’t a good choice for the 5D - used at f5.6 and over it will give beautiful results.  The loss of quality in the corners seems likely to be a problem with all film era lenses used with the full frame digital sensor on the Canon EOS 5D. However, only with really critical uses, such as architectural photography would these problems be a serious issue, and that’s not the sort of subject you’d shoot at full aperture.

Over the central 2/3 of the frame, results are superb - This a great lens.

Thanks to John Alexander for the loan of the lens.

© David Gold
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