The fastest standard zoom lens available for Micro Four Thirds system cameras boasts effective image stabilisation plus dust-and splash-proof construction.
The Lumix G X Vario 12-35mm f/2.8 ASPH was announced in May 2012 as an addition to Panasonic’s ‘X’ line of premium-quality lenses. Encompassing the traditional 35mm equivalent range of 24-70mm, it’s noteworthy for being the first (and, so far, only) standard zoom for a mirrorless camera system with a maximum aperture of f/2.8 across the zoom range.
The optical design of this lens features 14 elements in nine groups and includes four aspherical elements, one UED (Ultra Extra-Low Dispersion) lens and one UHR (Ultra High Refractive) lens to maximise edge-to-edge sharpness and contrast. Nano Surface Coating technology suppresses internal reflections across the visual spectrum (380nm-780nm) to improve light transmission and contrast and reduce the incidence of flare and ghosting.
Focusing is totally internal, with autofocusing driven by a stepping motor that is fast and near silent in operation. Manual focusing appears to be ‘by wire’, with no tactile feedback. The AF system can operate while movie clips are being recorded. Close focusing is limited to 25 cm from the subject, giving a maximum magnification of 0.17x.
Integrated POWER O.I.S. (Optical Image Stabiliser) technology compensates for both the low-frequency vibration generated when the shutter button is pressed and large, slow movements when using slow shutter speeds. Panasonic claims this system is twice as good as their previous system but provides no estimate of the degree of anti-shake correction with this lens, although we judge it to be approximately three f-stops.
Build and Ergonomics
Manufactured from high quality polycarbonate on a metal frame, this lens is very solidly constructed, with a chromed steel mounting plate that marries firmly to the camera body. The section of the barrel behind the zoom ring is made of metal. A thin rubber seal surrounds the mounting plate to prevent dust and moisture from entering the camera body.
Absolutely no slack could be found in any component and there was no zoom creep when the camera was carried with the lens pointing downwards. Both control rings provided smooth adjustments.
The focusing ring is also made of metal and has a finely-ridged surface that provides a very secure grip. It’s about 10 mm wide and located 13mm back from the front edge of the lens barrel.
This ring can be turned smoothly through a full circle manual if over-ride of autofocusing is needed. However, it’s electronically coupled to the camera (in a ‘focus-by-wire’ system) and gives no tactile feedback to indicate focusing limits. The GH3 can partly emulate the ‘feel’ of a mechanically-focused lens and provides focusing aids to make manual focusing easy and effective.
The zoom ring is 22 mm wide and located a few millimetres behind the trailing edge of the focusing ring. It has a 15 mm wide more broadly-ridged rubber grip band. Focal length settings for 12mm, 14mm, 18mm, 25mm and 35mm are stamped just inside its leading edge in an arc of approximately 80 degrees. Stops at each end of the arc limit the ring’s rotation.
Turning the zoom ring extends the inner barrel by 20 mm as you move from the 12mm to the 35mm position. There’s no distance scale to show where the focus is set. The only other control on the lens is the Stabiliser on/off slider, which is located around the left side of the lens barrel, just behind the zoom ring.
The front of the lens is threaded to accept 58 mm diameter filters (the same size as used by the 35-100mm lens). The filter doesn’t rotate during focusing, allowing easy use of angle-critical attachments.
The lens is supplied with a petal-shaped lens hood that has a bayonet mounting, a soft storage pouch and front and end caps. The hood is just over 35 mm long overall and it can be reversed over the front of the lens for storage.
The highest figures recorded for centre resolution occurred with wider aperture settings, notably around f/3.5, which appears to be the optimal aperture setting. Resolution declined gradually to about f/8, where diffraction began to take effect. Slight softening could be seen in the extreme corners of frames and, to a lesser degree, near frame edges. The graph below shows the results of our Imatest tests.
Lateral chromatic aberration was negligible across all focal length and aperture settings, as shown in the graph of our Imatest results below. The red line indicates the point of transition between ‘negligible’ and ‘low’ CA.
Panasonic cameras apply corrections automatically to JPEG files, so this is to be expected, whereas Olympus cameras don’t. We took a few test shots with our OM-D E-M5 body and found some coloured fringing in shots taken at 18mm and 25mm, although it was barely noticeable with the 35mm focal length.
Distortion is also corrected in Panasonic cameras, so it wasn’t surprising to find little evidence of distortion in test shots. Correction for vignetting is optional and accessed via the shooting menu. We found slight vignetting at the 12mm and 35mm focal lengths with f/2.8 but stopping down to f/3.5 eliminated it. Strong backlighting was handled well most of the time and Panasonic’s coating technology minimised the incidence of flare and ghosting in very challenging conditions.
The M4/3 format reduces the background blurring potential by approximately two f-stops, compared with a 35mm camera. However, the wide f/2.8 maximum aperture produced attractive bokeh in close-ups with the 35mm focal length, although out-of-focus areas weren’t quite as smooth and unobtrusive with the 12mm focal length.
The POWER O.I.S. stabilisation was very efficient and enabled us to hand-hold the camera and lens with shutter speeds as slow as 1/2 second at 35mm and achieve acceptable sharpness for about a quarter of the shots taken. At 1/4 second, more than half of the shots were reproduced sharply.
This lens was a pleasure to use on the GH3 body and its maximum f/2.8 aperture made shooting in very low light levels easy and satisfying. Combined with fast and accurate autofocusing and the sophisticated stabilisation system, this lens makes a superb partner for the GH3 for photographers interested in pushing the limits of low light shooting.
However, its high price tag (particularly for Australian buyers) causes us to have some reservations about recommending it, particularly for photographers who plan to fit this lens to an Olympus E-M5 body. Olympus includes sensor-shift stabilisation in its camera bodies, which makes in-lens stabilisation redundant. In fact, if you fit a stabilised lens to an Olympus camera you have to turn off the in-camera stabilisation system.
If you really need the f/2.8 aperture across the 12-35mm focal length range, this lens is the only option. But, if you can tolerate a slightly slower lens, Olympus offers a 12-50mm M.Zuiko Digital lens with f/3.5-6.3 maximum apertures for AU$499 (RRP). Its build quality is no match for the Panasonic lens. But we found it to be a good performer when we reviewed it in May 2012.
Additional image samples can be found with our review of the Panasonic DMC-GH3 camera.
Not so good for:
RRP: AU$1599; US$1299.99