Lens Test Panasonic Lumix GX 12-35mm f2.8 OIS

Introduction This is Panasonic's fourth standard zoom for the M4/3 system. First came the 14-45mm f3.5-5.6  OIS, which is still in production and offers excellent performance at a moderate price. Then came the budget 14-42mm f3.5-5.6 OIS often bundled with new bodies in a kit. Next came the 14-42mm f3.5-5.6 Power Zoom collapsing OIS lens designed,  I suspect mainly for video use. Now we have the 12-35mm constant f2.8 OIS lens which is a big jump up in specification and price from the other lenses. The 12-35 f2.8 is available separately or bundled with the GH3 body in some kits.

Place in the M43 system  The 12-35mm is the second Panasonic zoom aimed at the professional or serious amateur user at a premium price. The first pro quality zoom was the 7-14mm f4  ultrawide, the third is the 35-100mm f2.8 mid range tele zoom. 

Price, Primes and zoom range  Some M43 user forum members have expressed a view that this lens is "Too expensive". I thought it worth  putting some perspective on this idea with a list of the single focal length lenses for M43 which are covered by the 12-35, for which  I paid AU$1371 over the counter retail at a Sydney CBD camera shop. Prices from the same shop are:

Olympus 12mm f2,  $949

Panasonic 14mm f2.5, $539

Olympus 17mm f2.8, $339

Olympus 17mm f1.8, ?$600 ($499 at B&H New York)

Sigma 19mm f2.8, $225

Panasonic 20mm f1.7, $449

PanaLeica 25mm f1.4, $717

Sigma 30mm f2.8, $225

Obviously you wouldn't buy all of these lenses, for a total cost of $4043.  I have no wish to engage in the  "Zooms-vs-Primes" argument or even canvas the merits of one or the other in this review. However  I think the 12-35 does make a  stronger case than any previous M43 zoom to be a genuinely viable replacement for many primes.

Comparison with premium zooms from full frame and APS-C  This is one of those situations where a photo is worth a thousand words. Courtesy of the Camera Size website you can immediately see the difference between the classic 24-70mm f2.8 lens for 24x36mm sensors compared with lenses of the same field of view, zoom range and aperture for APS-C and M43. A price comparison may be of some interest to readers. Prices in Australian dollars, over the counter retail, GST paid.

Panasonic M43 12-35mm f2.8 OIS, $1371. New lens just released.

Canon EFS 17-55mm f2.8 IS,  $1399.  Lens has been in production for 7 years.

Canon EF 24-70mm f2.8 L Mk2 USM, $2389. New release Mk 2 version No IS.

Focusand zoom   The zoom action is smooth but not quite as smooth as that on the 45-150mm. The focus ring turns smoothly. In Focus Mode [AFS] and AF Mode [Single Area], autofocus on the Lumix G5 is so fast with most subjects one is hardly aware of it. All of my several hundred test frames taken in a wide variety of conditions  are sharply in focus.  Manual focus and AF+MF work well, with no problems. In a quiet room with one's ear on the lens, it can be heard making several little noises while operating.  These come from the OIS unit, the AF drive motor and the aperture diaphragm motor.  As usual with Panasonic OIS lenses this one rattles if shaken side to side when unpowered.

Optical Image Stabiliser   On my tests, OIS allows sharp results at 1-1.5 steps slower shutter speed than is possible without OIS. For instance a typical test run saw sharp frames from 1/13 sec  with OIS  at 35mm focal length, and from 1/30sec without OIS.   So, OIS works but the benefit on my testing is modest.

Shutter Shock   I found no evidence of blur, doubling or any other kind of image degradation which might have been attributable to shutter shock, at any shutter speed or camera support condition, tripod or handheld.

Aperture Diaphragm Actuation  On Page 10 of the (English Version) of the Operating Instructions for the lens the following slightly cryptic notice appears: "A sound is heard from the lens when taking a picture of a bright subject such as when outdoors.   This is the sound of lens or aperture movement and is not a malfunction."  In normal use the lens aperture remains fully open when the shutter button is half  pressed for acquisition of autofocus and auto exposure, closing to the set aperture only for the actual exposure. But in very bright conditions such as when a bright sky is included in the frame, the lens aperture will close down without user input. When I first encountered this behaviour I thought it was some kind of intermittent fault, but it appears to be a design feature the purpose of which is unknown to me. I have read on user forums that it may be to protect the sensor from excess light levels.

Sharpness/resolution  My benchmarks for testing were the Panasonic 14-45mm and 7-14mm  zooms. I did not have access to any single focal length lenses for comparison. I carried out my usual test protocol, photographing a test chart at 40x  focal length and a stand of casuarina trees with uniformly fine foliage at 1000x focal length. Then I made a few hundred photos of a range of subjects in different conditions. When viewing the resulting files on screen I make notes and frequently open pairs of files in ACR>Photoshop for direct side by side comparison. This method of lens evaluation is rather time consuming but does give me a broad based set of data for evaluation.

My experience is that test charts give me about half of the information I want about the performance of a lens. I have encountered many  which did quite well with evenly lit, high acutance chart targets but fell apart when subjected to more demanding conditions such as  backlighting, strong contrast, very low contrast or foliage against a hot sky.  What follows is a summary of the combined results of all the  tests.

The 12-35mm showed very high sharpness and rendition of fine details, right from f2.8 at all focal lengths.  The effect of stopping down was to increase the diameter of the circle of maximum resolution from about 80% of the frame at f2.8 to 100% at f4. Stopping down further increased the depth of field but not resolution which started to suffer from diffraction, which causes overall softness of the image, from about f8 and was really obvious by f11. There were no signs of optical weakness at any focal length and my copy is well centered.

Compared to the 14-45mm zoom the 12-35 at matching focal lengths gave slightly better sharpness, resolution and local contrast at f2.8 than the 14-45 could manage at any aperture. I should make it  clear, however that the 14-45 is a very good lens and I had to do a lot of pixel peeping at 100% with matched files to discover the 12-35 actually is the better performer by a small margin. On the test chart runs I could not separate them. It was only on  matched pairs of photos of many different real subjects that the superiority of the 12-35 became clear.  The main advantage of the 12-35 over the 14-45 is the extra 2/3 stop at the wide end and 2 stops at the long end.

Compared to the 7-14, the 12-35 files at f2.8 were indistinguishable from the 7-14 files at f4.

I was also testing the Panasonic 45-150mm lens at the same time and while this is a very nice budget  performer it is a step down from the 14-45 and two steps down from the 12-25 and 7-14. You would hope this might be the case, since the 12-35 costs 4.5x as much as the 45-150.

The most striking feature of the 12-35's optical performance is it's ability to render surface textures and fine details with great clarity. With apologies to some breakfast cereals, words like "pop" and "snap" spring to mind.    This characteristic might not translate fully to formal resolution measures expressed in line pairs per image height or similar, but  is evident when actual photographs are inspected.  For instance I photographed my wife and discovered from the photographs but not from my own eyes [which are not too bad, I can read a newspaper without spectacles]  that she had a very small lesion on the face for which a trip to the dermatologist was indicated.

Note that all my testing is done with RAW files. Due to the propensity for Panasonic JPG's [up to and including the G5 anyway] to soften fine details you will not get the most from this lens with Panasonic JPG capture.  The GH3 may have better JPG's,  we shall see.

Chromatic Aberration and purple fringing  Olympus camera users have reported clearly evident CA with this lens. This is corrected in Panasonic cameras even with RAW images so is not evident in the output files. Slight purple fringing can be seen towards the corners with some high contrast subject types [foliage against cloudy bright background]. This is controlled by slight reduction of the lens aperture.

Corner shading  is quite apparent at all focal lengths at f2.8, becoming less evident as the lens is stopped down 1-1.5 stops.

Drawing  There is moderate barrel distortion at the wide end, slight barrel at 25mm and mild pincushion at 35mm. This is the result after  in camera autocorrection, see comments below from the Photozone test report.

Bokeh  Rendition of out of focus subject elements is generally soft and smooth but  there is a slight tendency to tramlining and double imaging with some subject types, for instance small twigs in foliage or other straight sharp edged objects.

Contrast/microcontrast  This is the lens' forte. Files come straight out of the camera with a level of local contrast which would require a Contrast/Clarity boost in Adobe Camera Raw with some other lenses.

Flares  In general use the lens does not exhibit a problem with flare. Deliberate attempts to induce flare can  produce green blobs, magenta flares or veiling flare with the sun near the frame edge.

Close up  At 35mm the lens will focus down to 240mm from subject to sensor plane. This enables occasional close ups of  small subjects like flowers to be made hand held without the need for special macro equipment. The results are very acceptable.

Comment on published reviews  Evaluating and comparing published reviews can be difficult as each uses a different format for presenting results.

photozone.de  presented very good findings for resolution but was critical of the high level of uncorrected barrel distortion [5.8% as revealed in RawTherapee] at 12mm, describing this as "excessive"  They went on to describe Panasonic's  automatic in camera correction as "lossy" and "highly disappointing". They were also critical of the level of corner shading at f2.8. I think these comments form part of an ongoing debate about the best location for correction of chromatic aberration, possibly other aberrations, corner shading and distortion which are inherent lens characeristics. Should they be corrected in the lens, in the camera or  in the post capture software [such as ACR]  or all three ?  My own very careful observation has been that the [Panasonic] in camera correction of distortion with this lens produces very sharp, clear photos which do not appear to be "lossy" at all and are not in the least bit disappointing. Manufacturers  can presumably make lenses with very low inherent levels of CA, distortion and shading but I expect they would be much larger and more expensive.

slrgear.com   made a more positive report, essentially in line with my own findings. They reported the out of camera levels of CA, shading and distortion without much comment as to the source of corrections.

ephotozine.com  also produced a good report, again with high ratings for resolution, with little in the way of negative commentary.

Compatibility with Olympus cameras  When it was introduced, my understanding of the M4/3 format was that any M4/3 lens would work properly on any M4/3 body.  But in practice, this has only been partly true. All of them in my experience give correct exposure and mostly correct autofocus operation although I have found some Panasonic lenses focus more reliably on Panasonic cameras. Panasonic and Olympus zooms rotate in the opposite direction. Pansonic has in lens IS, Olympus has in body IS,  Panasonic autocorrects in camera a different set of lens faults than Olympus.  In consequence, I think it is fair to say that in several cases, Panasonic lenses work better on Panasonic cameras and likewise for Olympus.  So, what about the 12-35mm?  I have read several reports of clearly apparent chromatic aberration from this lens on Olympus cameras. So the 12-35 is a better match with Panasonic than Olympus cameras. However Olympus does not yet have a Pro level M4/3 standard zoom, leading some Olympus M4/3 users to mount the Olympus 14-54mm 4/3 lens on an adapter. But that combination is larger, heavier and slower to focus than the 12-35mm. I suspect that some Olympus users might  like to see a M4/3 version of the Olympus 12-60mm f2.8-4 [4/3 system] lens, although it would have to be larger and heavier than the 12-35.

Summary  Since the advent of the Micro Four Thirds format in 2008, there has been some uncertainty,  dare I say confusion, about the place of M43 in the camera world.  Some thought  it would be a platform for compact camera upgraders, some saw it as a "gap filler" between compacts and DSLR's.  I have always seen it as the format best positioned to supplant the APS-C  DSLR  as the most popular interchangeable lens system. Until now this prospect has not been realised due to a lack of sufficiently convincing M43 products. That has started to change. The Panasonic 7-14mm f4 has always been a pro standard ultrawide  zoom but has been a bit of an orphan with no pro system to back it up. Now we have the 12-35mm f2.8, the 35-100mm f2.8 and the GH3 body forming the core of a pro standard product set within the M43 system.

The 12-35mm f2.8 which is the subject of this review is fully capable of taking on a professional photographic role. It is a highly capable and versatile lens with excellent image quality, excellent mechanical operation and no deal breaker deficits.

It is not "perfect". The edges are not absolutely sharp until f4. Bokeh is good  but not perfect.  There is no distance scale. It is a varifocal not a parfocal.  [But a parfocal version would probably be larger] There is no AF On/Off switch on the lens barrel. Oh, yes, and mine has a bit of dust inside the rear element, on the periphery, thank goodness.  But the overwhelming impression is of a highly competent lens  capable of handling any photographic task, in a remarkably compact and reasonably priced package.  With this lens and it's pro grade companions,  the Micro Four Thirds system is coming of age.

Is it worth the money?  Should I buy it ?   Micro 4/3 system users are spoilt for choice with standard zoom lenses. From Panasonic there are the 14-42mm OIS, 14-42mm Power Zoom (collapsing), 14-45mm OIS, 12-35mm OIS and 14-140mm superzoom. From Olympus we have the 14-42mm Mk2 R (collapsing), 12-50mm with selectable macro and power zoom and the 14-150mm superzoom.

On the basis of my own testing of several of these lenses plus aggregated results from published test report sites, I rate the optical performance of these lenses on two levels. This is a bit aribtrary of course, but it helps me to get a sense of  where various lenses fit in the scheme of things.  Note that some of the lenses may be preferred for atttributes other than optical performance such as focal length range, image stabiliser, power zoom, collapsing barrel or macro capability.

I rank the  Panasonic 12-35mm near the top of  Level 1 and the Panasonic 14-45mm near the bottom of Level 1. The rest go to Level 2.  That does not mean they are bad lenses but the other two  are better optically.

So this is what I would suggest:

If you want the best and don't mind paying the price, forget the rest, get the Panasonic 12-35mm. And, to follow the logic, also get a Panasonic GH3 body and Panasonic 35-100mm f2.8 lens to round out a pro standard twin lens kit. At this level total cost is a very substantial consideration so the gear had better be good.  The 12-35 is good, I will report on the other two items when I can get my hands on them.

However if you are more budget conscious the question is more difficult to answer. The Panasonic 14-45mm probably delivers the most optical performance for the dollar.  If you are more concerned about compact size then one of the collapsing zooms would appear to be an obvious choice. The Olympus 12-50mm is very versatile without breaking the bank and the Panasonic 14-140mm has a solid reputation as a superzoom with very decent optical quality.

You pays your money and makes your choice. Good  luck.