CameraLabs reviewed the new lens and concluded:
The Olympus 8-25mm f4 Pro is a fresh and very welcome addition to the Micro Four Thirds system. There’s lots of ultra-wide or standard zooms in the catalogue, but few that effectively cover both ranges. The earlier Leica DG 8-18mm started very wide but often left you wanting to zoom a little longer. Then the Leica 10-25 sacrificed a little at the wide end to extend further while delighting with its bright and constant f1.7 aperture, but this made it a heavy and expensive option for most of us. With the 8-25mm f4 Pro, Olympus has successfully filled the gap between the two Leicas, starting as wide as one and ending as long as the other, but opting for a more modest f4 aperture to keep the size, weight and cost down. The retracting mechanism also allows the lens to shrink to a compact size without getting in the way of operation. The result is a lens that delivers a very flexible range from ultra-wide to standard coverage with useful close-up focusing and a compact size. Sure the f4 focal ratio on Micro Four Thirds means you won’t be enjoying shallow depth-of-field effects unless your subject is very close, but that’s about the only sacrifice to achieve what’s arguably one of the most compelling walkaround lenses in the system. If I had to choose just one lens for general use on a Micro Four Thirds body, the Olympus 8-25mm would be it, and it comes highly recommended.
And if you wanna see how good this lens is check out the first review posted by Radojuva.com. The summary:
*low cost (about 110 $)
*light weight, metal mount
*quiet stepper motor
*small Minimal Focus Distance
*AF / MF focusing mode switch
*one low-dispersion element and 2 aspherical elements in the optical scheme
*good optical performance overall
*there is a complete incompatibility with some old cameras (the lens is not recognized by the camera)
*AF / MF focus mode switch does not work with some cameras (lens always uses autofocus)
*no hood included; non-bayonet type hood
*the diaphragm control makes a noticeable noise
*original lenses are more compact and with a smaller filter diameter (52 mm for Yongnuo 25 / 1.7, versus 46 mm for PANASONIC 25 / 1.7 and OLYMPUS 25 / 1.8)
*no USB port for firmware updates
*poor backlight resistance, noticeable vignetting at F / 1.7
And here is the review from Richard Wong:
ePhotozine published the full review and concluded:
Much of the GH5 II is the same or very similar, you get the same 20mp Micro Four Thirds sensor, with improved sensor-based 5-axis image stabilisation, combined with the lens’ optical image stabilisation, which gives benefits for both stills photography and video recording. You’ve also got 6K Photo, and you can shoot unlimited photos at 30fps, giving you 18-megapixel images. 4K Photo shoots unlimited photos at 60fps, although these are at a resolution of 8 megapixels.
Image quality from the camera is very good, with the camera producing pleasing images, with good levels of detail, and good colour. The use of a Micro Four Thirds sensor, which is smaller than APS-C CMOS sensors means that at high ISO settings noise performance isn’t as good as APS-C or FF cameras, however, the camera does produce usable results up to ISO3200 and ISO6400. This is likely to be the case until Micro Four Thirds sensors make the next leap in sensor technology, to backside-illuminated sensors.
For some, the lack of phase-detection AF could be disappointing, and there are times when continuous AF will hunt or wobble when recording video.
The GH5 II offers a list of video features and specifications beyond what most people need, but the headline features are that the camera can record unlimited 4K video, with higher quality recording possible internally, without the need of an external recorder, plus Live Streaming support (at up to FullHD resolution).
The Micro Four Thirds system is ideally suited to 4K video, as the compact range of lenses means the system is much smaller than if you were to use a full-frame (or APS-C) DSLR for 4K video recording. High-speed FullHD video recording is also available at up to 180fps.
If CINE 4K is something you need, or you do any video, then the 5-axis image stabilisation system will help here, dramatically improving the stability (and professional look) of your videos, without the need of a tripod, and this gives the GH5 II (and other cameras with in-camera IS) an advantage over most DSLRs.
You also benefit from a very good electronic viewfinder (EVF), which features a high resolution of 3.68m dots, and the magnification is good at 0.76x. This makes using the EVF a pleasure, with impressive levels of detail visible. The 3.0inch touch-screen is also very good, letting you quickly change settings and options. Battery life can be extended to 1200 shots with energy-saving options switched on.
If you’re a stills photographer primarily, then the Panasonic Lumix G9 or Olympus OM-D E-M1 Mark III could be a better choice. Then there are also a variety of APS-C cameras available with higher resolution on offer, from Sony, Canon, and Fujifilm.
If you shoot video then the GH5 II is a great choice, assuming you don’t already have the GH5, and assuming you can’t wait to see what the GH6 is going to offer. If you don’t need higher speed video (4K 120fps: Canon EOS R5, Sony Alpha A7S III, or 8K: Canon EOS R5, Sony Alpha 1), then the GH5 II is a great choice, and is also considerably cheaper than these alternatives. If you don’t need live streaming, then the GH5 is likely to be great value for money while still available, but if you’re looking for live streaming, then the GH5 II is a great choice.
The Panasonic Leica DG Vario-Summilux 25-50mm F1.7 ASPH is an optically outstanding, outrageously fast lens that will particularly appeal to videographers thanks to its killer combination of a de-clicked aperture ring and focus clutch mechanism with linear manual focusing.
With stellar performance throughout the aperture and focal ranges, it could conceivably replace a number of prime lenses in your camera bag, such is the optical quality on offer.
It is undeniably large and heavy, though, being much better suited to life on larger Micro Four Thirds camera bodies like the Panasonic GH5 II that we tested it with, and the clickless aperture ring is less convenient for stills shooters who want to quickly set a specific aperture (although you can switch this setting to the camera body if you’d prefer).
The Panasonic Leica DG Vario-Summilux 25-50mm F1.7 ASPH zoom offers a rather unique focal range of 50-100mm, covering everything from “standard” 50mm shots to moderate telephoto, and as such it proved to be a very versatile walkaround lens.
There’s some noticeable vignetting, particularly at 25mm, but otherwise it delivers fantastic sharpness at virtually all focal lengths and apertures, even right at the edges of the frame, and distortion and chromatic aberrations are very well controlled too.
Build quality is very good, to be expected given the premium price-tag, and the fact that this lens is weatherproof is the icing on an already rich cake, although note that Panasonic do stop short of calling it fully weatherproof.
Price-wise, it’s best to judge the Panasonic Leica 25-50mm as a viable alternative to buying several other prime lenses, rather than just being a single zoom lens that happens to cost a whopping £1,799.99 / $1,799.99. You could just invest in the 25-50mm and not have to worry about having to buy any more lenses in that focal range, it’s that good.
In summary, the Panasonic Leica DG Vario-Summilux 25-50mm F1.7 ASPH is a unique, versatile and optically outstanding lens that is a must-buy for pro videographers and seriously tempting for everyone else.
If I were a Panasonic MFT user, then I would be looking very closely at this lens. It is a remarkably useful lens, focusing close, delivering superb quality, handling well. I can even forgive the catch on the lens hood as it can be worked around. The changeover point of 25mm with its f/1.7 sibling seems to have been finely judged and the two lenses together would make a powerful pair indeed.
The description of moisture and dust resistance seems to be hedging bets a little, but Panasonic are not alone in being slightly vague on the matter. The price is also quite high, but that is reflected in the quality offered.
In summary, overall the Panasonic Leica DG Vario-Summilux 25-50mm f/1.7 ASPH is a very fine lens well worth very serious consideration. Highly recommended.