Panasonic Leica DG Vario-Summilux H-X2550 25-50mm

Autofocus in the 98th percentile and a constant f/1.7 aperture make this Leica zoom a powerhouse for portraits and video. It's heavy and pricey, and objective bokeh rankings lag at the 34th percentile, but real-world images are stunning. If you're on M4/3 and need the brightest standard zoom available, this is it.

Autofocus is blisteringly fast, sitting in the top 2% of all lenses we've tested. That linear motor tracks subjects silently and accurately, making it a dream for both stills and video. Optically, it's one of the best in its class: central sharpness is excellent even at f/1.7, with only a slight drop in corner sharpness wide open. Our objective bokeh metric lands at the 34th percentile, but real-world shots from the 9-blade diaphragm can look creamy and beautiful. The 25–50mm range (50–100mm full-frame equivalent) turns this into a portrait and short-tele workhorse rather than an everyday zoom, earning a versatility score in the 74th percentile, so it's above average but not a do-it-all lens. The constant f/1.7 is where it shines, giving you over a full stop more light than any other Micro Four Thirds zoom.

Compared to the Canon RF 28-70mm f/2.8 IS STM, the Leica offers a full stop more light (f/1.7 vs f/2.8) and isolates subjects more due to the 50–100mm equivalent reach, but the Canon adds stabilization and a wider field of view on full-frame. If you want a fast prime on Sony E-mount, the Viltrox Air 15mm f/1.7 is a fraction of the price and opens to f/1.7 too, though you lose zoom flexibility entirely. For M4/3 users eyeing a budget alternative, the Olympus 12-40mm f/2.8 PRO covers a more versatile range for about half the price, while sacrificing that extra stop and some autofocus speed.

At $1800 (and as low as $1610 from some retailers), the Leica DG Vario-Summilux is a serious investment for a Micro Four Thirds lens. In our value scoring, it lands just above average for professional use (68/100) but drops to a mediocre 64.5/100 for budget-conscious shooters. With prices swinging $1123 between vendors, it's smart to shop around for the lowest price. For the performance, especially the constant f/1.7 and top-tier autofocus, many pros will see it as a worthwhile tool.

The Leica DG Vario-Summilux 25-50mm f/1.7 lands in the 98th percentile for autofocus speed among all lenses in our database, pairing a linear motor with a bright constant f/1.7 aperture that's rare for a standard zoom. Optical performance hits the 86th percentile thanks to 16 elements (1 aspherical, 3 ED), and owners back that up with consistent praise for sharpness and rich color rendering. At 654 grams it's a chunky piece of glass for Micro Four Thirds, and while the build feels tank-like, our database ranks construction in the middle of the pack (56th percentile). Weather sealing, a de-clicked aperture ring, and a manual focus clutch make it a go-to for video shooters.

Skip this lens if you're on a tight budget or need a do-it-all zoom; its narrow 25–50mm range (74th percentile for versatility) won't cover wide landscapes or long telephoto shots. If you don't have a body with IBIS, the lack of stabilization (bottom third) will be a pain for handheld video or low-light stills. And if macro is your thing, the 0.21x magnification and 50/100 macro score will leave you wanting.

The Panasonic Leica DG Vario-Summilux 25-50mm f/1.7 is a specialty lens that earns its spot with near-perfect autofocus and a constant f/1.7 aperture that's unrivaled in the Micro Four Thirds zoom world. If you're a portrait shooter or videographer who demands shallow depth of field and lightning-fast focus, this is the lens to get. Just be ready for the weight, the lack of stabilization, and the sticker shock.