There have been quite a few reviews for this lens, particularly the E mount version, so let’s take a look at the L mount version. Not everybody needs such a long telephoto lens, but if you do (and if you have an L mount camera), the Sigma 100-400mm f/5-6.3 DG DN OS lens might be for you.

We tested this out mainly on the Panasonic S1R, but we also did some testing with the Sigma FP and the Leica SL2, so let’s get straight to it.

This is a Contemporary lens, so not part of the Sigma ART lens lineup, but it still has really good image quality and build quality. It almost looks like it’s a native lens on the Panasonic S1R.

The E mount version of this 100-400 lens is clearly competing against the Sony 100-400 lens, which we reviewed alongside the Sony A9 II earlier this year. This L mount version we have, though, is one of the few options on the market for folks who might want to get into birding or sports photography.

There are 22 elements, 16 groups in the lens and the lens only weighs 1,135 grams, so it’s not a very heavy lens for a 100-400mm zoom. The lens also has image stabilisation, with two options. It’s pretty interesting, however; we noticed that we got more stable shots with the image stabilisation set to the first setting than the second. Typically it’s the other way around.

It’s a telescopic zoom lens, which we’re not the fondest of, but it is what it is. At this price point though, it comes in far less than the Sony counterpart, and there’s nothing else like it in the L mount alliance. There’s a zoom lock button to keep it from sliding open in bags or cases though, so that’s nice.

In terms of performance though, autofocus speed is really dependent on the camera you pair it with. The S1R was relatively fast to lock on, it almost feels on par with a native Panasonic lens. The Sigma FP’s performance was a bit hit and miss in certain lighting conditions.

And we don’t think this lens was designed for the FP, it feels more like it was designed for bigger cameras like the S1R and SL2. Also, this is a variable aperture lens, and one of our biggest criticisms is that this lens changes aperture quite fast.

It starts off at f/5 at 100mm and jumps to f/5.6 at 112mm before topping out at f/6.3 at 241mm onwards. 12mm of f/5 isn’t great, but the difference between f/5 and f/5.6 depends on your lighting situation. We’ve found that this lens performs at its best when you’re shooting in brightly lit areas. If you want to shoot in dim areas, you’ll end up having to crank up the ISO.

Image quality though is excellent. Shots are sharp and portraits are quite natural.

We managed to test the lens out with the Sigma FP and at first glance, photos seem to be sharp. But once zoomed in, you’ll notice there’s some camera shake. This is because of how light the FP is, and due to the disparity in weight between the camera and lens, the image stabilisation of the lens alone isn’t enough.

The Leica SL2 produces some of the sharpest images out of a full-frame camera that we’ve seen to date, and that trend continues with this lens.

Overall, this lens is a very sharp, well-performing lens, especially at this price point. It would be nice to see Sigma come up with an ART version for this, but it would definitely be a lot more expensive. There really isn’t any other option at this focal length for L mount camera users, aside from the Panasonic 70-200mm which could be used with a teleconverter. If you have that lens, maybe save some money and go with the teleconverter, but if you don’t and you just want one lens that can do 100-400mm, this is it.

For more information about the Sigma 100-400mm f/5-6.3 DG DN OS (S$1,388) or to support us, you can get it on Amazon here.