Panasonic Lumix G 20mm f/1.7 ASPH - Review / Lens Test Report
Lens Reviews - (Micro-)Four-Thirds

Review by Klaus Schroiff, published October 2009


The Panasonic Lumix G 20mm f/1.7 ASPH is a newly designed lens for micro four-thirds format cameras. It is a so-called pancake lens because ... well ... it is just as flat - just 2.5cm in this case. Pancake lenses tend to be rather "slow" but Panasonic managed to squeeze out an ultra-large max. aperture of f/1.7. In terms of its depth-of-field capabilities this is about f/3.4 in full format terms, the focal length is equivalent to 40mm. As such it is a very moderate wide-angle prime lens - such lenses are typically used for e.g. street photography. As of the time of this review it is either sold separately for 400EUR or combined with the Panasonic GF-1 for about 850EUR. This is not exactly cheap so let's have a look whether it's worth it ...

The build quality of the dwarfish Panasonic lens is excellent - there isn't much potential for shaky components here anyway. It is tightly assembled based of a high quality plastics for the lens body and a metal mount. The inner lens tube extends marginally when focusing towards closer focus distance.

Typical for most micro 4/3 lenses the focus ring is operated "by wire" so you drive the AF motor by turning the focus ring (unlike the conventional mechanical coupling). At least the author has no problem with this approach. The AF speed is very high and typical for all contrast AF systems the accuracy is spot on.

Equiv. focal length40 mm (full format equivalent)
Equiv. aperturef/3.4 (full format equivalent, in terms of depth-of-field)
Optical construction7 elements in 5 groups inc. 2x aspherical elements
Number of aperture blades7 (circular)
min. focus distance0.2 m (max. magnification ratio 1:7.5)
Dimensions25.5 x 63 mm
Weight100 g
Filter size46 mm (non-rotating)
Hoodbarrel-shaped, optional
Other features-