Comparison of 300mm L vs 100-400mm L

I hired a Canon 300mm f/4 L IS USM prime lens from Lenses For Hire a few weeks ago, and took it to Chester Zoo to put it through its paces. I was also interested to see how it performed against my existing Canon 100-400mm f/4-5.6 L IS USM, with the assumption that the prime would be sharper as well as having a greater maximum aperture at 300mm. I’ve heard stories about bad 100-400mm lenses, and while it should be obvious if a lens is really bad, it’s harder to say if it’s just a little soft without having an equivalent lens to compare to.

The below shots are full size output from each lens, taken with a Canon 7D. They have been converted from RAW using Bibble with the standard settings and no other colour/sharpness/contrast adjustments. As these were taken with an APS-C sensor, it’s important to note that the images are using the central part of the lens, which is normally sharper than the far extents. Using these lenses on a full-frame camera will yield different results.

The images are of York Minster and are cropped – the left hand side is the far left centre of the image, the right hand side is the centre of the image. Conditions were not optimum as it was getting later in the afternoon, so this isn’t a scientific comparison but should give some indication of real-world results.

Including the full size crops directly in this post is probably a bit insane, but makes it easier to view side-by-side.

Full size images

First up, full size JPEGs converted from the original RAWs without any cropping so you can do your own assessment – click through for each.

300mm f/4 at 300mm f/8

100-400mm f/4-5.6 at 300mm f/8

300mm f/4 at 420mm f/8 (with 1.4 extender)

100-400mm f/4-5.6 at 400mm f/8

300mm, f/5.6

300mm f/4 at 300mm, f/5.6

300mm f/4 at 300mm, f/5.6

100-400mm f/4-5.6 at 300mm, f/5.6

100-400mm f/4-5.6 at 300mm, f/5.6

300mm, f/8

300mm f/4 at 300mm, f/8

300mm f/4 at 300mm, f/8

100-400mm f/4-5.6 at 300mm, f/8

100-400mm f/4-5.6 at 300mm, f/8

300mm, f/11

300mm f/4 at 300mm, f/11

300mm f/4 at 300mm, f/11

100-400mm f/4-5.6 at 300mm, f/11

100-400mm f/4-5.6 at 300mm, f/11

This final image has captured additional contrast accidentally, making it look more defined. I will try to post up a closer match to the previous image. However, across the different apertures the two lenses perform well, with the 300mm prime very slightly sharper in the centre of the image (here, the right hand side), and a slight lack of clarity starting to appear at the edge of the 100-400mm.

400/420mm, f/5.6

3 sets of comparisons now at 400/420mm, with the prime lens affixed to a 1.4x extender and the 100-400mm at maximum focal length.

300mm f/4 at 420mm, f/5.6

300mm f/4 at 420mm, f/5.6

100-400mm f/4-5.6 at 400mm, f/5.6

100-400mm f/4-5.6 at 400mm, f/5.6

400/420mm, f/8

300mm f/4 at 420mm, f/8

300mm f/4 at 420mm, f/8

100-400mm f/4-5.6 at 400mm, f/8

100-400mm f/4-5.6 at 400mm, f/8

400/420mm, f/11

300mm f/4 at 420mm, f/11

300mm f/4 at 420mm, f/11

100-400mm f/4-5.6 at 400mm, f/11

100-400mm f/4-5.6 at 400mm, f/11

The centre of each lens appears to be equivalent here, with both suffering slightly compared to the 300mm shots due to the addition of the 1.4x extender and the extension to the 100-400mm’s maximum focal length. The addition of the 1.4x extender to the 300mm prime lens has introduced some noticeable chromatic aberration, particularly against the stones on the very far left, and the right hand outline of the first tower as it meets the sky. The 100-400mm is also affected, but to a much smaller degree and is disguised by being yellow in colour compared to the cyan of the 300mm.

I’d be interested to hear if you’ve had similar or different results, or if you have any comments on the methodology. As I mentioned, this wasn’t scientific but gives a reasonable real world comparison.

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