Panasonic GH2 - Zoom or Prime?


I've recently sold my Leica Panasonic 14-150mm Vario-Elmar Zoom. Wonderful lens, but big, heavy and bulky. I'm currently using an Olympus m.Zuiko 14-150mm f/4-5.6. There's a test at Dpreview - http://www.dpreview.com/lensreviews/olympus_m_14-150_4-5p6_o20/ Their conclusion is a bit luke warm. 

"Overall then the 14-150mm is superzoom that delivers a perfectly competent results in a small light package. Its image quality may not please the most critical of photographers, but unless you regularly examine your images at 100% or make large prints (A4 or bigger) its flaws are unlikely to be hugely apparent. In combination with a Pen-series camera it makes a highly flexible general-purpose package with image quality to match an SLR but without the associated bulk. So while it's perhaps not a lens for the purist photographer, for many others it will make a very agreeable travel companion indeed."

I've always thought its actually a pretty decent lens however, and yesterday I did some tests to compare it with what are generally regarded as the two best m4/3 prime lenses. The Panasonic 20mm f/1.7 and Panasonic Leica 45mm f/2.8 macro. 

These are pairs of shots taken on the same camera (A Panasonic GH2) at the same settings and the same focal length. If you click through to flickr there are full size images to view. (Though these are heavily jpg compressed, so expect a few artefacts.)

Olympus 14-150mm  Panasonic 20mm f/1.7  GH2

Olympus 14-150mm  Panasonic 20mm f/1.7  GH2

Olympus 14-150mm  Panasonic 20mm f/1.7  GH2

Olympus 14-150mm  Panasonic 45mm f/2.8  GH2

Olympus 14-150mm  Panasonic 45mm f/2.8  GH2

Olympus 14-150mm  Panasonic 45mm f/2.8  GH2

For some reason most of the pictures taken with the zoom are slightly darker than with the primes but what I see from this is how similar they are. Even when the zoom is wide open. I was certainly expecting to see much more of a difference with the primes producing significantly sharper results. They do look slightly sharper to me but not as much as I would have expected.

Not really a scientific test but one thats actually very useful for me. The primes obviously have other advantages such as wider apertures and macro facility, but for everyday use in good light there seems little advantage in using them. Certainly only a very slight sharpening in Photoshop for the zoom shots would be required to make them look identical.

I always had the feeling that the Olympus 14-150mm was producing good results and it was a factor in my decision to sell the Vario-Elmar. Certainly the Olympus zoom is a pleasure to use, being very light and it also has very fast AF on the GH2. 

So a very useful exercise for me and with a somewhat unexpected result.