Panasonic 20mm 1.7 ASPH LUMIX G 20 mm II review @ Panasonic GX7

Panasonic 20 mm f/1.7 is very attractive for street photography, wedding photography or other occasions where you want to be as unobtrusive as possible as a photographer. And it’s an ideal travel companion for your holidays.

Construction and Auto focus

This compact lens is solidly built and beautifully finished despite its low weight. There are minor differences in appearance between the Panasonic 20 mm 1.7 (left) and the Panasonic 20 mm f1/7 II (right). The first version of the lens had a gray body with black focusing ring. Version two has a black body. Also, the black plastic on the front reflects more on the new lens than on the old model. The second version appears, due to the materials chosen, somewhat more sophisticated.  

In the image on the right, you can see how compact the combination of the Panasonic GX7 with this pancake lens is. The drive of the auto focus is a “drive by wire” system, meaning you don’t feel any mechanical resistance when focusing manually. The focus ring also keeps turning if you’ve reached 20 cm or infinity. That takes some getting used to. Auto focus of the Panasonic 20 mm 1.7 I on a Panasonic GX7 happens quickly and accurately. However, recent models of Panasonic lenses, such as the Panasonic 14-140 mm or the Panasonic 12-32 mm, focus a bit faster than the Panasonic 20 mm f/1.7.

Image stabilization

This lens is so compact; there is no room for image stabilization. But considering the focal length and the brightness of this lens, image stabilization will seldom be missed.

With the in-camera image stabilization of the Panasonic GX7, we saw a modest profit of 1 to 2 stops.

Vignetting

Only at maximum aperture does this lens suffer from vignetting. That’s not unique to this lens, with bright lenses on a camera with a full frame sensor it’s also common. Because this is one of the few micro-43 lenses with a brightness under f/2, many photographers will choose a large aperture because of the beautiful background blur. Fortunately, vignetting is easy to correct afterwards with software if it’s a problem.

Distortion

The distortion of this lens is for both the RAW files (at most RAW converters) and jpg files automatically corrected. The end result is very good.

If you make a portrait on the street with a 50 mm lens on an SLR camera, then the subject might be intimidated by quite a big camera at a relatively short distance. With this little pancake lens, you have no problems with that.

Bokeh

The background blur of the Panasonic 20 mm delivers a nice bokeh. It isn’t yet entirely comparable to the bokeh of a bright lens on a camera with a full frame sensor, but almost certainly good enough for 99.9% of the photographers who want to play with depth of field. At maximum aperture the bokeh de to vignetting from round in the center to a cat’s eye in the corners, as you can clearly see in the picture below.

Click (2x) on the image at right for a larger version of a practice shot.

Flare

It seems that version 2 of the Panasonic 20 mm 1.7 is less sensitive to flare than the first version. We found it difficult to detect that difference. When testing the Panasonic 20 mm 1.7 v2 in the testing lab under extreme conditions, we occasionally encountered flare (such as in the sample shown here). In the pictures taken in practice that we made during the day and even in most night shots, we did not run into that.

If you’re planning to do night photography with this lens where there are a lot of street lights, then you will occasionally encounter flare. That also applies to many other lenses.

Resolution

We used the space on the right to show the lens design. For the connoisseurs among us: 7 lens elements, including two aspherical, in 5 groups.

In order to compare MTF50 results for this lens with MTF values for lenses tested on cameras with an APS-C or full frame sensor, we set the micro-43 test camera to a 2: 3 ratio. In other words: we tested this lens with a resolution of 14 megapixels (2:3 ratio) instead of 16 megapixels (4:3 ratio). Using the native 4:3 aspect ratio will yield slightly higher MTF values.

The sharpness of the Panasonic 20 mm 1.7 II in the center is very high; this was the case for both our practice shots and our measurements. The Panasonic GX7 test camera is probably the reason that we measured a higher resolution for version 2 than in our testing of version 1 (with a Panasonic GH2 camera).

From the measurements, it appears the resolution outer corners always lags relative to the center. In practice that is not noticeable, because the resolution in the outer corners up to aperture 4 remains well over 1000 LW/PH.

Chromatic aberration

According to Panasonic, the use of 2 aspherical lenses ensures that chromatic aberration is minimized. In addition, both the RAW files (at most RAW converters) and the jpg files are automatically corrected for chromatic aberration.

In our practice shots, we have encountered no chromatic aberration with the Panasonic 20 mm 1.7, and the measurement values for chromatic aberration are also very low.

Conclusion Panasonic 20 mm 1.7 ASPH LUMIX G II review with Panasonic GX7

See our list of tested lenses or our list of tested micro-43 lenses to compare the performance of this lens to other lenses.

Pros

• High sharpness
• Low chromatic aberration and distortion
• Bright
• Nice bokeh
• Compact design and lightweight
• Solid construction and nice finish

Cons

• Vignetting at full aperture
• Manual focusing without resistance

Our conclusion about the Panasonic 20 mm f/1.7 v2 is unchanged from the first version. The Panasonic 20 mm 1.7, whether you’re talking about version 1 or 2, is a nice lens without major disadvantages. It is an attractively priced, bright, compact and light pancake with very good optical performance. The Panasonic GX7 test camera is probably the reason we measured a higher resolution for version 2 in our testing than for version 1 (with a Panasonic GH2 camera). From the measurements, the resolution in the outer corners always lags behind compared to the very high resolution in the center. In practice, this isn’t noticeable. Practice shots are rich in contrast, sharp and have a nice bokeh. At maximum aperture, the vignetting is correctable with software, in those situations where the disturbance is visible.

This micro-43 standard lens is an ideal partner for a Panasonic GM1 or a Panasonic GX7. If you prefer a zoom lens with the same dimensions, then the 20 mm 1.7 II has a competitor in the Panasonic 12-32 mm, which we recently tested.

As good as this micro-43 lens is, it comes out even better when you compare it to all other lenses with an equivalent field of view, tested on SLR cameras with an APS-C or full frame sensor. We have so far tested 75 lenses with virtually the same field of view as the Panasonic 20 mm f/1.7 on various cameras with a micro-43, APS-C or full frame sensor. The Panasonic 20 mm 1.7 image quality falls among the 15 best lenses for micro-43, APS-C and full frame. When you realize that some lenses have been tested on a camera with 36 megapixels, while this test is performed on a 16 megapixel camera, then it’s clear that the Panasonic 20 mm f/1.7 II in terms of value for money and ease of use is a very attractive offer.