Sigma 100-300 f/4 vs Canon 300 f/4 IS and Canon 100-400

Canon 300 f/4 IS, Sigma 100-300 f/4, Canon 100-400 IS. Click here to enlarge.

The Sigma 100-300 f/4 is an unusual tele zoom: unlike the majority of other tele-zooms in its price range, it has a constant maximum aperture of f/4. It is cheaper than Canon 100-400 and 300 f/4, and it is not much bigger, in spite of the aperture and internal zoom. I had heard very positive opinions about its image quality, so I have decided to compare it against the Canon 100-400 and the Canon 300 f/4 IS. How does these lenses compare, with and without teleconverters?

Specifications

Built quality, stabilization and autofocus

The two Canon lenses have identical built quality; the sigma 100-300 is similar - for sure it looks solid, but it has the usual Sigma finish that scratches easily. The Canon 300 f/4 and the Sigma 100-300 are nearly identical in size, while the Canon 100-400 is a bit smaller. The two zooms have completely different zoom systems: the Canon has a push-pull design, while the Sigma has the classic "rotating" design...wich one is better is purely a matter of personal tastes. Other than that, the Canon 100-400 extend considerably when zooming, while the Sigma 100-300 has internal zooming: this is an advantage for the Sigma, because it reduces the amount of dust (and water, in case you shot under the rain) that may enter into the lens.

All these lenses are supplied with a large lens hood. The metal hood of the Sigma looks better than the cheap plastic hood of the Canon 100-400; the Canon 300 f/4 instead has an unusual built-in, non removable lens hood. As far as I know the Canon 300 f/4 and 400 f/5.6 are the only Canon lenses with this design, and I like it: it is very compact and you will never forget it at home. It is also much easier and faster to use than conventional lens hoods.

Canon 300 f/4 IS, Sigma 100-300 f/4, Canon 100-400 IS, with hood. Click here to enlarge.

The Canon 300 f/4 IS has the fastest AF, but there is not a big difference. All three lenses have ultrasonic motor AF with full time manual focus; the Canon lenses have even a two-steps focus limiter, that improves a bit AF speed. The Sigma has a very large rubber ring for manual focus, it gives a better impression than the tiny ring of the Canon 100-400.

What I really miss in the Sigma lens is image stabilization. Even thought the Canon 100-400 and 300 f/4 have only first generation IS, it helps a lot during handheld shooting. Of course if you have a sensor-stabilized camera it is not a problem, but I am sure that Canon and Nikon users would really appreciate stabilization into the Sigma 100-300.

Image quality comparison

I have tested the lenses on my Canon 1DsIII (21 megapixel, FF). The lenses was mounted on tripod; I have used mirror lock up and self timer. The following images are 100% crop from the center of the unprocessed RAW file. (note: s100 is Sigma 100-300, c100 is Canon 100-400, c300 is Canon 300 f/4).

300mm:

	f/4 (wide open)	f/5.6
s100
c100
c300

The Canon 300 f/4 is the sharpest of the three, even though the 100-400 comes close. The Sigma is clearly softer, in particular at f/5.6 (surprisingly, it gets worse stopping down!).

400/420mm:

	f/5.6 (wide open)	f/8
s100
c100
c300

At 400mm, the 100-400 (without teleconverters) is a little sharper than the 300 f/4 + 1.4x. That said, keep in mind that the 300 + 1.4x gives a 420mm, while the 100-400 at maximum exstension (400mm) is actually a 370mm, so it has less reach than the 300. The Sigma 100-300 is a bit softer at f/5.6, and it is clearly softer at f/8.

560/600mm:

	f/8 (wide open)	f/11
s100
c100
c300

At 600mm, the 300 f/4 + 2x is the sharpest, but even the 100-400 + 1.4x is not bad, even though it is a bit softer and it shows more chromatic aberration. The Sigma is softer than the two Canon, both wide open and at f/11.

Conclusions

The Canon 100-400 and 300 f/4 IS offer similar image quality; the 300 f/4 is slightly sharper, but it is not a big difference: you have to decide if for you it is more important the versatility of the zoom or the slightly better image quality than the 300 f/4. (personally I'd go for the 100-400, unless you want to use the tele for macro - in this case, the 300 f/4 has a clear advantage thanks to its 1:4 macro ratio).

The Sigma 100-300 f/4 has good built quality and a nice range, but looking at the results of this test I wouldn't buy it. Actually I am surprised - I had read very positive reviews of this lens. Maybe I got a bad copy? This is actually the second copy of Sigma 100-300 that I try - the first copy was clearly defective, half of the frame had extremely poor contrast. This copy has good contrast, but it is not as sharp as I expected (for example, the much more extreme zoom Sigma 50-500 is way sharper)...

If I have the occasion, I'll test a third copy of Sigma 100-300 f/4, to see if it gives better results.

Do you have comments or questions?

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