Ophrys Photography

Wildlife photography by John Devries, Kent UK. Inspirational images from nature.
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Canon 100-400 f4.5-5.6L is mkii Optical Comparisons.

canon 100-400 mkii

Comparisons with 400mm f5.6 prime lens.

Starting images. Taken with same tripod position (4.5m) and camera (Canon 5DmkIII) the zoom was set to 400mm. NB all lenses and cameras were optimised for micro focus adjustments using the Reikan Focal system prior to testing. A Yongnu LED panel provided the light source and the tests were carried ou indoors in my kitchen!

All tests were carried out using mirror lockup and a wireless cable release on a sturdy Gitzo tripod and Markins ball head.

Iso was 200 throughout. All images were converted using Adobe Camera RAW with no noise reduction or sharpening unless mentioned.

starting image 400 f5.6Starting uncropped image 400mm f5.6 (sharpened)

100 to 400 starting image
Starting uncropped image 100-400mm mkII (sharpened)

Notice how the 400mm image is larger ? The 100-400 mk II is more like 380mm than 400mm at the long end and mirrors its predecessor in that respect. The image quality looks pretty similar.

100% crops - Totally unsharpened

400 f5.6

100-400 100-400mm


When cropped at 100% the resolving power of the two lenses at the centre is pretty similar. If I had moved the tripod forward a little to match the size of the 400mm f5.6 image they would be pretty indistinguishable. This is impressive performance from a zoom lens.

Same lenses compared at various apertures.

starting image
Starting image (sharpened)

100% unsharpened crops

100-400 mk ii
400mm 5.6

f 5.6

400mm f5.6 at f5.6



400mm at f8



400 at f11



400 at f16

100 to 400
Repeat of the above on a different day

Once again the 100-400 mkII is holding its own at all apertures against the 400mm f5.6. The images are not totally comparable as the 400mm f5.6 lens is giving a larger true 400mm image vs the 380mm of the 100-400 mkII. Should a manufacturer be selling a 100-380mm lens as a 100-400 ?

Due to the focal length difference the 400 prime has a magnification benefit in my tests above. Despite this I can see no significant resolution advantage even so.
That said, the 400mm f5.6 did look particularly good at f5.6 for some reason. I therefore repeated the f5.6 test again on a different day under different lighting conditions and the differences were pretty negligible. These are huge magnifiations of a small subject taken at a considerable distance (5.4metres) both lenses did very well and I'm prepared to call this battle a draw.

As the images have all been unsharpened I have taken the f5.6 image for the 100-400 and optimised it and sharpened it. This is the 100% crop:

100to400 sharpened

I think that this is a pretty astonishing result for a zoom lens when compared to a very good prime.

How does the 100 to 400mm mkII take to a converter ?

I have both a Canon 1.4x mkIII and 2x mkIII converters so I wondered how the new lens would behave with them. The 1.4x converter effectively becomes a 560mm f8 lens at the long end (or 532mm if you consider that the reach is really only 380mm bare) and also retains autofocus when using Canon 1Dx or 5DmkIII bodies. OK this is pretty "slow" but in good light, this is serious focal length and very useful for birders.

I have never fitted a 2x converter to a zoom lens before. It just doesn't make sense as a converter just magnifies what is in front of it warts and all. Most zoom lenses are simply not up to taking converters if you take image quality seriously. Nevertheless, I thought I would try. Unfortunately as the lens is now effectively an 800mm f11 ! autofocus is lost and the lens would only be usable in very good light unless the subject is static.

1.4x f8


f 8



Once again, I am pretty astonished at the performance this lens is putting in. The lens is surprisingly usable with a 1.4x converter and I wouldn't hesitate to do so. I have not tested the 400 f5.6 again here, but I know from experience that is also takes a 1.4x very well. It appears that the 100-400 can also pull off this trick.

With the 2x converter the performance has degraded but is still surprisingly good. Lets take that worst case 2x converter at f11 and optimise it :


And at 100% :
I don't think I will be using a 2x with the 100-400 ii but I think that this illustrates that you could if you had no alternative.

2xsharpened 100%

Conclusions so far.

For many years, bird photographers have been begging Canon to make a 400mm f5.6 with image stabilisation. I have a feeling that day will never come, but what we have here is perhaps the nearest thing to it.

It is unfortunately double the price of the 400mm f5.6 but it does offer a staggeringly good, near silent 4 stop stabiliser and incredible close-focusing ability. Plus it has all the benefits and convenience of a zoom down to 100mm. I am now going to have to think long and hard about keeping my 400mm f5.6 as this lens is just as sharp and far more versatile.