I had been contemplating an upgrade from the Canon 70-200/4 to the the IS version, which everyone online raves about, even though the MTF charts don't suggest a radical improvement in areas where the non IS version is found wanting. OTOH the IS version may be a stellar performer in the 80-190mm region, if so, Canon might wish to reconsider presenting their optical data similar to the way that Leica does, as the 70-200mm f4 is a much better lens away from the ends of the zoom range.
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| 20 lens elements in 15 groups |
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| 10 and 30 lp/mm % contrast curves blue colour f8- solid lines sagittal, dashed - meridional. Canon MTF charts for 70-200mm f4 IS |
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| 16 lens elements in 13 groups |
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| 10 and 30 lp/mm % contrast curves blue colour f8- solid lines sagittal, dashed - meridional. Canon MTF charts for 70-200mm f4 |
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| 10, 20 and 40 lp/mm % contrast curves solid - sagittal, dashed - meridional www.photodo.com MTF chart for Canon 70-200mm f4 |
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| 10, 20 and 40 lp/mm % contrast curves solid - sagittal, dashed - meridional www.photodo.com MTF chart for Leica 80-200mm f4 |
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| Leica tech data Vario Elmar 80-200mm f4 @ 80 mm |
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| Leica tech data Vario Elmar 80-200mm f4 @ 100 mm |
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| Leica tech data Vario Elmar 80-200mm f4 @ 135 mm |
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| Leica tech data Vario Elmar 80-200mm f4 @ 180 mm |
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| Leica tech data Vario Elmar 80-200mm f4 @ 200 mm |
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| 12 lens elements in 8 groups |
Testing of zooms, at stopped down apertures, at infinity, on scenery with randomly orientated 'high frequency spatial detail' in my opinion needs a wooded valley of some width and a variety of views across and along the valley axis with sky lined branches / horizon. On my doorstep, the topography of the Forest of Dean and Wye Valley fortunately has a few elevated locations for telephoto zoom lens testing, which is handy when the infinity focus at 200mm and f8 is ~140m. There were also elevated view points inside the woods where image comparisons at the wider end of the zooms could be made. Testing setup was tripod positioned on hard ground, MLU, cable release and manual focus in live view @10x magnification across the image to ensure everything was in focus. I'll add that when testing lenses for resolution, wind can be a pain on subject matter and good air clarity.
The quality of both lenses needed Pixel peeping of test images to establish the resolution capability, which subjectively determined that -
The R displayed minimal chromatic aberrations.
It was a close call for resolution in the dead centre of the image, but not at all focal lengths.
Sometimes the L lens, sometimes the R, away from the centre the R outresolved the L for fine detail across the image into the edges and corners.
I never noticed any effect of field curvature effects stopped down and live view focusing.
The lenses were also tested over some manually set white balance settings and in my opinion the Leica images had more vivid colour. The analogy I'd use would be to compare an image file in Adobe RGB improperly converted to the sRGB colour space and the colour takes a hit through a smaller gamut envelope.
I didn't test specifically for flare resistance between the two lenses, but subjectively I'd say the Canon has better flare resistance and the Leica has a built in hood for good reason, it's worth employing the hood at all times in all lighting. Typing of hoods and there's a good reason Canon doesn't show the hood attached in any marketing information, it makes for a great weathervane in any wind ...
Build quality of the Leica R zoom was impressive, in a different league to the Canon L lens, as was the manual focus compared to the Canons, to be fair to the Canon though it can auto focus and has electronic aperture control.
The Leica is slightly physically smaller, but is heavier than the Canon (1.05 kg incl leitax adapter and caps vs 0.81 Kg incl hood and caps).
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| Leica R 80-200/4, Canon L 70-200/4 and lens hood |
Some caveats to the testing. The Canon was a hands down winner over the 70-80mm focal length. The L lens was purchased from new and has seen heavy use, I've no idea on the Leica zoom history of use. I didn't notice vignetting as being an issue for either lens and never checked for distortion, the woodland scenery was mature oak and beech, with downy and silver birch trees, not subject matter that lends itself to distortion analysis. Over 6 years of use, the Canon lens had seen some exposure to wet weather and dusty/pollen conditions and despite its reported environmental sealing limitations, the internal glass is clean and I've had no issues. I could find no information on the Leica environmental sealing. There's also the consideration of a lens mass produced for a photography market requiring autofocus capability vs a far lower production volume lens for a niche of manual focus photographers.
What I found interesting was how optical lens diagrams didn't correlate with actual optical performance. The 12 element 8 group optical design of the Leica R zoom and the 15/12 and 20/15 optical designs of the Canon L f4 zooms. I had been led to believe additional lens elements groups were used to correct for higher aberrations, this wasn't the case from my subjective testing. Anyone researching Leica R lenses will end up reading the observations and insights of Erwin Puts, and it soon becomes apparent that he has an enquiring mind, has some knowledge of Leica's history, products and access to Leica's designers and engineers, more importantly he writes from the perspective of a photographer, not a marketing drone. The review of the 80-200mm f4 mentions six elements with anomalous dispersion glass and/or high refractive index and a total of eleven different glass types used. The lens rendition of colour was also a surprise and not something I had expected, I've no idea why the colour was better - coatings, exotic glass types, better colour correction, fewer lens elements reducing the number of air/surface interfaces or maybe a combination of factors, oh and engineering tolerances?
Those who know about these matters state that manufacturing and assembly tolerances can have the greatest impact on image quality, from precision grinding of a lens surface, to alignment of lens elements inside the lens barrel, there will be an engineering tolerance build up. Which could create a Catch 22 scenario, where increasingly complex lens designs aimed at improving optical performance actually degrade image quality through engineering tolerance build up. Those lenses that pass quality assurance - inspection and testing - of a defined performance point should demonstrate some variability in performance courtesy of tolerance stacking. The excellent www.lensrentals.com blog has a few posts demonstrating the variability of lens performance.
http://www.lensrentals.com/blog/2013/09/there-is-no-perfect-lens
http://www.lensrentals.com/blog/2015/03/a-quick-zoom-variation-demonstrationhttp://www.lensrentals.com/blog/2015/06/measuring-lens-variance
And it seems optical performance variation also exists within 50mm f1.4 primes, the Zeiss Outus 55/1.4 variability might be due to a complex aspherical element ...
http://www.lensrentals.com/blog/2015/07/variation-measurement-for-50mm-slr-lenses
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