Sigma 100-400 Review: This Lens Almost Changed What I Shoot

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The Sigma 100-400 gives you a 150-600mm equivalent range on APS-C. I can honestly say I've never used a zoom that goes that far — and after spending three weeks with this lens, I think I need to buy a telephoto for myself now.

Sigma sent this lens out to me for testing. They're not paying for this review, and I had to send it back after three weeks, which was harder than I expected. Here's my honest breakdown of what this lens is actually like to shoot with.

First Impressions and Build

This lens has some real weight to it — no getting around that. But for what you're getting, it's justified. It's part of Sigma's Contemporary line, same as the 16-300, but this one has a noticeably more robust feel. When you're dealing with a focal range this large, that robustness has to be there.

The lens includes a locking switch, and you'll want to use it. Unlocked, this lens will absolutely creep due to the weight of the internal elements. You also get an autofocus lock switch, a macro switch that lets you toggle between the full six meters to infinity focus range or stay within six meters for closer work, and a function button.

My favorite feature on this lens is the optical stabilization switch, which gives you two distinct modes. One mode softens stabilization on the horizontal axis specifically for tracking sports or moving subjects. The other locks you down as tightly as possible, ideal for tripod work. At focal lengths this long, stabilization matters enormously — even locked off on a tripod, small bumps and micro movements become very visible at 400mm, regardless of how good your camera's in-body stabilization is.

Size and Portability

I expected this lens to be a lot bulkier than it turned out to be. Collapsed, it's roughly the same size as a 70-200mm — though obviously that comparison isn't perfectly fair since a 70-200 typically runs a fixed f/2.8 aperture while this is variable. Still, going from 100 to 400mm in a telescoping design and having it collapse down to fit comfortably in a standard camera bag is genuinely impressive.

Sigma also managed to keep the filter thread at 67mm despite the massive focal range, which is a detail I appreciate. It keeps your filter investment consistent across lenses rather than forcing you into a larger, more expensive filter size.

Aperture and Real World Shooting

This is a variable aperture lens running from f/5 to f/6.3, which is standard for a 100-400 zoom. The range isn't dramatic, and even at 100mm and f/5, you can get meaningful background separation from your subject.

I took this lens out to Central Park to see what I could actually capture, and the results genuinely surprised me. I got a macro shot of a bee that opened my eyes to a type of photography I hadn't really explored before. This lens does a lot more than just reach — the versatility across its range caught me off guard.

Autofocus: The One Real Drawback

The autofocus system on this lens is older, and it shows more in video than in stills. For photo work, it's genuinely solid. For video, you'll notice slower focus acquisition and occasional focus hunting as the lens tries to lock onto a subject.

Worth noting — I was testing this on Fujifilm, which doesn't have the strongest autofocus system to begin with, so this may be less of an issue on a system like Sony. But if you're planning to shoot primarily video with a lens like this, be aware the autofocus won't be as snappy as more recent Sigma releases.

What I'd Change

Two things I'd genuinely like to see Sigma address in a future version.

First, this lens doesn't come with a lens collar. At a focal range this long, you want the option to mount the lens itself to a tripod rather than the camera body, which keeps the weight distribution balanced. Sigma sells the collar as a separate accessory rather than including it in the box. Given how premium this lens feels otherwise, including the collar standard would make it significantly more competitive.

Second, updated autofocus motors would go a long way, particularly for anyone using this lens for video work.

Who Is the Sigma 100-400 For?

This is a lens for someone who wants to do serious telephoto work — sports, wildlife, safari, anything requiring real reach — without spending premium camera-manufacturer pricing. At just over $1,000 at the time of testing, comparable telephoto lenses from major camera brands often run at least twice that price, and I don't think you're getting twice the performance for it.

To be clear, this isn't a budget lens. It's a premium, purpose-built piece of glass. What Sigma has done well here is deliver genuinely high image quality at a more approachable price point than the alternatives — and that's a meaningful distinction.

If you're the kind of shooter who knows you're going to live in telephoto range regularly, this lens deserves serious consideration. I had a shoot lined up with the Yankees to use this lens on before a trade deadline roster shuffle got in the way. If that opportunity comes back around, this is the lens I'll be reaching back out to Sigma for.

If you pick this lens up for yourself, I'd love to know what you're planning to shoot with it. Link is in the description of the video below.

If you want to see my full breakdown, the full video is available HERE