This review will be looking at the lens being used on a Panasonic and Olympus Micro Four Thirds cameras, namely, the GF2 and E-PL2.
DesignThe Panasonic 20mm f/1.7 lens is a well built and sturdy lens, weighing at 100g. It's slightly larger than the Olympus 17mm f/2.8 lens. The manual focusing wheel is nicely-damped. There's no optical image stabilization.
The filter thread is 46mm so you can add on stuff like the lens hood shown below (bought off eBay).
AutofocusAutofocus is fast enough but not instantaneous. When you half-press the shutter, you still have to wait a split second before focus is locked.
Focusing causes the lens element to move, and operating noise is audible. The operating sound might be an issue if you have autofocus on while recording videos.
SharpnessCentre sharpness is excellent so let's just look at the edge sharpness.
The images below are taken on the GF2 and E-PL2, on a tripod with 2s timer.
At wide open f/1.7, the edges are a bit soft, with improvement in sharpness when stopping down.
f/2.8 seems to be the sharpness sweet spot. From the comparison above, it seems that GF2 is producing softer images, but I've used it on the GH2 and the sweet spot is also f/2.8.
Chromatic AberrationUsing the same set of images above, you can spot slight chromatic aberration when used on the Olympus body (E-PL2 in this case). It's software-corrected on the Panasonic body.
DistortionDistortion is not noticeable in real life.
VignettingThere's some vignetting when shooting wide open. It's not corrected by camera software.
BokehThe bokeh or background blur is a slightly harsh (at least to me). The image below was shot at f/1.7 (see any vignetting?).
Lens flareThe lens can suffer from lens flare if you point it in the right direction. In a separate photo, I pointed it into the sun and there's no flare.
The Panasonic 20mm f/1.7 lens is a good performer. At f/1.7, it's wonderful for shooting at low light. The speed of auto-focusing and vignetting at wide open are the more noticeable issues.
It's a 40mm equivalent so it's in between the common 35mm and 50mm. It's not really wide enough for say architecture or landscape shooting but it's great for streets and close up.
At a glance
+ Well built, sturdy
+ Small, light weight
+ Large aperture, great for low light shooting
+ Good image quality
+ Excellent centre sharpness
- Edge softness when shooting wide open
- Auto-focus speed takes a while
- Vignetting at wide open
- Chromatic aberration not corrected on Olympus body
- Audible operating noise when lens is zooming
AvailabilityPanasonic 20mm f/1.7 lens is available on Amazon (US | UK | DE | FR | IT | JP)
Be sure to check out more reviews on Amazon.