Canon EF 70-200mm f/4 USM L IS II Review - Analysis
Lens Reviews - Canon EOS (Full Format)
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Introduction
Analysis

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Distortion

The Canon EF 70-200mm f/4 USM L IS II produces a low to medium degree of image distortion. At 70mm we can spot a mild barrel distortion that switches to pincushion distortions in the upper focal length range. At the far end, they reach 1.75% which is a bit on the high side for this type of lens.

Vignetting

The vignetting characteristic is about typical for a lens in this class. At fully-open aperture, the light falloff varies between 1EV (70mm) and 1.6EV (200mm). Stopping down by 1 f-stops reduces the issue to an almost negligible degree at the wide end whereas you may prefer to stop down a little more at the 135mm and 200mm marks.

MTF (resolution) at 50 megapixels

In the introduction, we mentioned that the mk I lens produces a stunning sharpness but that was back in the days. So how does the mk II perform at 50 megapixels? Well, we are more than impressed for sure. At 70mm the center reaches excellent levels at f/4 and f/5.6 although there's still a bit of headroom here. The borders/corners are very good. Stopping down improves the quality only slightly. Diffraction effects limiting the resolution are getting more obvious at f/11. The sweet spot is in the middle range where the center zone is pushed to superb quality and the borders/corners improve a little as well. The center sharpness is maintained at 200mm whereas the quality of the outer image region is slightly reduced albeit it remains on a very high level.

The centering quality of the tested sample was very good. There's minimal field curvature at 70mm.

Please note that the MTF results are not directly comparable across the different systems!

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

MTF (resolution) at 21 megapixels

Many users are still using cameras with a more moderate pixel count so let's have a look how the lens performs with the eased requirements at 21 megapixels - also in order to be able to compare the results to older reviews.

Unsurprisingly the results are "better" still on pixel level because the pixel density is lower. Generally the quality is just outstanding and a tad higher than on the mk I at longer focal lengths.

Please note that the MTF results are not directly comparable across the different systems!

Below is a simplified summary of the formal findings. The chart shows line widths per picture height (LW/PH) which can be taken as a measure for sharpness. If you want to know more about the MTF50 figures you may check out the corresponding Imatest Explanations

Chromatic Aberrations (CAs)

Lateral chromatic aberrations (color shadows at the image borders) are very low. At 70mm, they vary around the 1.1px mark at the image borders. CAs are at their lowest (negligible) level in the middle range and increase just slightly again towards the 200mm end.

PS: The CA figures were taken at 50 megapixels.

Bokeh

Due to its max aperture of f/4, the Canon lens isn't perfectly aligned to shallow depth-of-field photography but it is, of course, capable of doing so if you stick to fairly short focus distances.

Near-center highlights are nicely circular at f/4 up to f/8. The inner highlight zone is pretty smooth with minimal outlining at the highlight edge.

The circular highlights deteriorate to the usual "cat eyes" the more you move to the image corners (see below at f/4). Stopping down helps with this albeit from a real-life perspective you won't really do so due to the small max aperture anyway.

When looking at the general quality of the blur in the focus transition zone, it's very smooth in the image foreground (to the right). The image background (left) shows is somewhat rougher though.

Here's a snap from the real world showing the background:

Sample Images

Sorry, no sample images this time. Mr. Lumbago paid a visit (...).

Competition

There is a variety of alternatives out there. You should still be able to shop for the mk I for a while and even the ancient Canon EF 70-200mm f/4 USM L (without image stabilizer) is still available here and there - and that's an oldie but goodie as well at a much lower price point. As far as current production lenses are concerned, the most obvious competitor is the new Tamon 70-210mm f/4 Di VC USD. We haven't tested this lens yet but Tamron doesn't classify it as an "SP" lens - their professional grade lineup - so it is very unlikely that it can touch the Canon EF 70-200mm f/4 USM L IS II really. However, it is also much cheaper at just 800USD/EUR. An option that may produce more headaches regarding your preference may be the Tamron SP 70-200mm f/2.8 DI VC USD G2. We haven't tested this one either but that one is certainly a serious lens and it resides at the same price point as the Canon lens but it is one stop faster. However, as it goes with f/2.8 lenses, it is also much bigger and heavier.

Visual comparison courtesy of camerasize.com.

Verdict

The king is dead and, yes, long live the new king. The Canon EF 70-200mm f/4 USM L IS II is everything that the mk I was plus some. It is the perfect playmate for ultra-resolution Canon cameras. It is mostly tack sharp at mainstream settings with no real weakness across the focal length range. Lateral CAs are low and not really an issue. Image distortions can be visible specifically at the long end though and you can spot some moderate vignetting at f/4. If you use digital auto-correction that will be a lesser concern, of course. The quality of the bokeh is Okay for a zoom lens but it has its shortcomings.

The build quality is excellent but that's hardly a surprise when talking about a Canon L lens. The low weight and small size are certainly welcomed when carrying around your camera gear all day long. Canon's improved image stabilizer is impressive. Funnily the EF 70-200mm f/4 USM L IS II is at least as good as EF 70-200mm f/2.8 USM L IS III regarding low light photography because the latter's IS delivers a gain of 3.5 f-stops vs 5 f-stops for the f/4 lens - that is in static scenes. The ring-type USM is fast - as usual - but it doesn't seems to have improved over the mk I lens.

So the final question is whether you have to buy one? :-) If you want the ultimate in image quality from a medium tele-zoom lens - maybe. However, you have to live with the moderate max. aperture of f/4. Whether this is a real limitation for you is something only you can answer. The price tag is fairly hefty but then it is aligned to the delivered quality. Therefore - highly recommended!

Optical Quality
(at 50 megapixels):		 to
Optical Quality
(at 21 megapixels):
Mechanical Quality:
Price/Performance:
      
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