Panasonic 25mm f/1.7 ASPH LUMIX G
Lab Test Results
March 13, 2016
by Andrew Alexander
The Panasonic 25mm ƒ/1.7 ASPH made its appearance in September 2015, expanding Panasonic's lineup of prime lenses with a conventional "50mm-like" Micro Four Thirds prime lens. Panasonic has had its more expensive version of the "nifty fifty" available for some time, the 25mm ƒ/1.4, but at over $600 compared to the new ƒ/1.7's $250 price tag, it may have been a little to expensive for the casual user.
The new 25mm ƒ/1.7 is compatible with all Micro Four Third mount bodies. It comes equipped with a round lens hood, accepts 46mm filters, and will cost you around $250.
In a word: exceptional. The Lumix 25mm ƒ/1.7 provides sharp images straight out of the gate at ƒ/1.7, and while stopping down technically provides statistically sharper images, you'd have to peep pretty closely to see any kind of practical difference.
Diffraction limiting starts in at ƒ/11, but you probably won't notice any practical impact on sharpness until ƒ/16; even at ƒ/22, images are still decently sharp.
While there is probably some post-processing going on under the hood of our Panasonic GX1 test camera, chromatic aberration is well-controlled in this lens/camera combination. Where CA is visible, it shows up in areas of high contrast as magenta fringing.
There is some corner shading present when the lens is used wide open: we note corners that are 2/3 of a stop darker than the center when the lens is used at ƒ/1.7. This improves to a half stop when the lens is used at ƒ/2; at ƒ/2.8 or smaller, corner shading is negligible.
There's no distortion to speak of when using the LUMIX G 25mm ƒ/1.7 ASPH; again, probably because there is some post-processing going on with the GX1. Either way, it's great to see.
The Panasonic 25mm ƒ/1.7 is very fast to focus: it takes well less than one second to slew through the entire range of focus. When doing so, it is very quiet. Filters attached to the front element don't rotate.
The 25mm ƒ/1.7 is not a notable macro lens, offering just 0.13x magnification with a minimum close-focusing distance of 25cm (about a foot).
Build Quality and Handling
The 25mm ƒ/1.7 is very lightweight at just 125 grams (just over 4 ounces). The lens features 8 elements in 7 groups, including 1 UHR (Ultra High Refractive Index) and 2 aspherical elements. Its seven circular diaphragm blades make up the aperture for nice background blurring. It is pretty svelte in its design -- there are no buttons, indicators or scales. The only point of operation is the manual focus ring.
The manual focusing ring has a plastic ribbed texture and is a generous 3/4" wide. The ring will turn forever in either direction, not being limited at the infinity or close-focusing distances. The front element accepts 46mm filters, and does not turn during auto or manual focus.
The lens ships with the H-H025 hood, a round hood with matte black ridges in the interior to cut down on veiling flare. The hood is 1 inch long, and can be reversed to mount on the lens for storage.
The lens is available in black or silver; also included is a "decoration ring" which protects the bayonet mount, in case you are not using the lens hood.
Panasonic 25mm ƒ/1.4 ASPH LEICA DG SUMMILUX ~$600
It may cost a little more, but if you want or need the extra partial stop of light-gathering ability, it's worth it. It's only slightly larger and heavier, and where the two lens overlap in aperture settings, the 25mm ƒ/1.7 version is slightly sharper; however, you would have to peep very closely indeed to see the difference. Really, it is all about needing or not needing the ƒ/1.4 aperture.
Olympus 25mm ƒ/1.8 M.Zuiko Digital ~$400
While the design is very different, the two lenses are very similar in their test results; however, the Olympus has a bit more distortion, but less corner shading.
Sigma 30mm ƒ/1.4 DC DN Contemporary ~$400
Sigma doesn't produce a 25mm lens in Micro Four Thirds format, but it does produce its 30mm ƒ/1.4, which would give you a similar field of view. We haven't yet tested this lens.
Panasonic has done very well with this lens: for the price point, you get a very sharp, very capable lens that's easy to use. If the kit lens isn't fast for your needs, the Panasonic 25mm ƒ/1.7 would be an excellent companion.
The VFA target should give you a good idea of sharpness in the center and corners, as well as some idea of the extent of barrel or pincushion distortion and chromatic aberration, while the Still Life subject may help in judging contrast and color. We shoot both images using the default JPEG settings and manual white balance of our test bodies, so the images should be quite consistent from lens to lens.
As appropriate, we shoot these with both full-frame and sub-frame bodies, at a range of focal lengths, and at both maximum aperture and ƒ/8. For the ''VFA'' target (the viewfinder accuracy target from Imaging Resource), we also provide sample crops from the center and upper-left corner of each shot, so you can quickly get a sense of relative sharpness, without having to download and inspect the full-res images. To avoid space limitations with the layout of our review pages, indexes to the test shots launch in separate windows.
Panasonic 25mm f/1.7 ASPH LUMIX G
Panasonic 25mm f/1.7 ASPH LUMIX G User Reviews
10 out of 10 points and recommended by David_Ruether (2 reviews)Sharp to the corners over a wide range of stops; Low CA; Excellent for infrared photography; Compact and light-weightNone (other than for not having in-lens stabilization - but I don't find this a problem for my use)
From http://www.david-ruether-photography.com/MFT-Lenses.htm#25mm (photo samples are also there) -reviewed March 24th, 2016 (purchased for $99)
This compact, fast, and light "normal" lens for the MFT format performs very well over a wide range of stops (from wide open at f1.7 to a bit beyond f11). For many purposes (including for shooting infrared photos, for which it is excellent), this lens is a very good choice since it is sharp to the corners even wide open, and (on Panasonic bodies, which automatically correct in-focus CA with JPGs) it exhibits few CA problems even when used under the most difficult conditions. This lens is another "keeper"!