Originally posted by pathdoc The compactness of micro four thirds is somewhat illusory. To me they are nothing more or less than the inheritor of the rangefinder camera, but with the electronics giving them all the WYSIWYG benefits of an SLR. I saw some of the early Olympus bodies a while back and was briefly entranced - not least because they are about the size of a Pentax MX or their own ancestors the OM series*, and they have film-like knobs on - but some of the high-end Panasonics are not much smaller than an APS-C DSLR (if that), and to me that defeats the point. To me, Micro 4/3 only makes sense with wide to normal focal lengths in a compact lens package, with a longer zoom occasionally cribbed on.
I've seen one or two professionals on YouTube use them, but this is in the setting of significant amounts of studio lighting (either in studio or in the field with portable powerpacks); they can supply all the light they need or want, and that wipes out any disadvantage the smaller sensors have at high ISO or low light, while leaving them with all the advantages of pixels per square mm.
If I wasn't eyeball deep in Pentax (M42, K film and K digital), I'd seriously consider Olympus M4/3... but only as a travel and social-snapshots camera, not as the heart of a serious professional system.
* IMO the smaller sensor was designed to allow the EM series to be constructed around it as their spiritual successors, and capitalise on nostalgia for the OM's. Olympus may not have kept the same lens mount, but they certainly understand the importance of legacy.
Micro 4/3 came about from 4/3. 4/3 wasn't small at all. It had a mirror and longer flange distances. It was also quite high end minded. The goals were lofty and some of the lenses were pretty amazing but sensor technology lagged. M4/3 brought a considerable size reduction and huge gains in IQ have been made at the sensor level and at the camera processing level.
Olympus pen F is distinctly like the Nikon Df in that it is a retro design made to capitalize on nostalgia. But most Panasonic designs are pretty simply function dictating form in two basic designs (slr-like and rangefinder-like) most Olympus cameras are similarly aligned to one of these designs.
As for size, it is no illusion. My GX-1 paired with a 14-42 and 30-100 has the same functionality of a much larger package and covers 28-200mm equivalence f3.5-5.6. Sure it is slow and the sensor isn't happy at low ISO, but compare the capabilities to old 35mm film and you start to rethink things. My 35-100 is similar in performance to the 70-210 a series f4 lens from Pentax but slightly slower on the long end and fits in my hand allowing my fingers to wrap around it and touch. Even my dad's GX-7 and 35-100 f2.8 is drastically smaller than my K-3 and 50-135 f2.8.
And sure I realize the apsc advantage in ISO and depth of field so I understand the comparison isn't direct. But effective shooting under normal lighting is possible and the package has very good IQ.
Putting smallish primes on m43 leads to even more compact systems with faster apertures. It is a good system, but I'm so invested in Pentax it is hard to maintain two systems at high quality so I keep a super compact m43 travel system and a tricked out apsc Pentax system.