Sigma

This Sigma 100-400mm is a compact, razor-sharp telephoto that weighs just 710g and costs under $900 at legit retailers. Optical performance is top-tier (97th percentile), and the 4-stop stabilizer works great. If you can live with the slow aperture and meh bokeh, it's a killer value for Sony E-mount.

Sharpness is the headline here; this lens resolves beautifully even at 400mm, and our database ranks it in the top 3% of all lenses we've tested. Autofocus with the stepping motor is snappy and accurate, good enough for casual birding and moving subjects, though not quite sports-car fast (87th percentile). Stabilization is a standout, buying you around 4 stops of handholdability, which helps offset the dim aperture. On the downside, the bokeh is nothing to write home about—20th percentile, so backgrounds can look busy and onion-ringy. The build is decent but not pro tank-like; 53rd percentile means it's middle of the pack, with a weather seal that should handle light drizzle but maybe not a downpour.

The Sony FE 100-400mm f/4.5-5.6 GM is the obvious rival: it's faster, built like a tank, and focuses quicker, but it's heavier, larger, and costs over $2,000. This Sigma is about 40% lighter and 60% cheaper. Then there's the Tamron 50-400mm f/4.5-6.3 Di III VC VXD, which gives you a wider range and slightly faster aperture at the wide end, but it's pricier and bigger. If you're comparing to the Sigma 150-600mm Contemporary, that lens has more reach but is significantly heavier and doesn't handle as nicely on smaller Sony bodies. For most people, the 100-400 Contemporary is the sweet spot for portability and value.

Prices for this lens are all over the place, ranging from a very reasonable $879 at Newegg to an absurd $22,010 from some third-party sellers. Ignore the crazy high listings, and at the sub-$900 mark this lens is a bargain. You're getting optical performance that rivals glass at triple the cost, in a package you can toss in a daypack. For Sony shooters who want a 100-400 without paying GM money, this is a no-brainer. Yes, the aperture is slow, but that's the trade-off for this size and price. If you need speed, you'll have to spend a lot more.

Sigma's 100-400mm f/5-6.3 DG DN OS Contemporary is one of the most sensible telephoto zooms for Sony E-mount if you value a compact build and sharp images above all else. At just 710g, it's easy to carry all day and doesn't scream for attention. Our testing shows it's punching well above its price class in optical quality, sitting at the 97th percentile among all lenses—right up there with glass costing three times as much. That means crisp details across the frame, minimal flare, and colors that pop with the Super Multi-Layer Coating.

It's not a lens for every situation though. The f/5-6.3 aperture is slow, so low light and background blur aren't its strengths. But for hiking, wildlife from a distance, or landscape compression shots, it's a fantastic tool. The built-in OS stabilizer gives you about 4 stops of leeway, which pairs nicely with Sony's IBIS.

Skip this lens if you need a fast aperture for background separation or low-light work. The f/5-6.3 max aperture and unexciting bokeh will frustrate portrait shooters and indoor event photographers. Also, if you're after a lens with serious macro capability, look elsewhere; this one's minimum focus distance is over 5 meters. Heavy-duty wildlife pros who need lightning-fast AF might want the Sony GM or a prime telephoto instead.

If you're a Sony shooter who wants a telephoto zoom for travel, hiking, or casual wildlife, this Sigma is one of the best deals around. It's sharp, light, and stabilized effectively. You'll miss it if you shoot portraits or need fast shutter speeds in dim woods, but that's not what this lens is about. It's an outdoor daylight lens that delivers excellent results where it counts. At under $900, it's hard to beat.