I must say I've been mightily impressed with what Panasonic have done with micro four thirds. These small light cameras have opened up all sorts of possibilities for photographers.
Firstly - The ability to use lenses from many different manufacturers, via adapters, allows some combinations that I could only dream about, and at a (mostly) reasonable price.
Allowing for the 2x crop factor I now have the 35mm equivalent of lenses such as:-
70mm F/2 (from Nikon 35mm F/2), 100mm F/1.1 (from Voigtlander 50mm F/1.1), 100mm F/1.2 (from Nikon 50mm F/1.2), 150mm F/2.5 (from Voigtlander 75mm F/2.5), 170mm F/1.8 (from Nikon 85mm F/1.8) & 270mm F/2.8 (from Nikon 135mm F/2.8). The size and price of 35mm or full-frame equivalents of lenses such as these is huge on both counts. With the exception of the Voigtlander 50mm F/1.1, which I bought new & was expensive, all of the others are relatively inexpensive, many being bought second hand.
Secondly - despite the size of the four thirds sensor, which is half the size of a 35mm or full-frame one, the quality of the images is terrific. Panasonic have been fairly restrained in their use of their Anti Aliasing filter, which helps to control noise & moire, with the result that the images the camera produces are sharper than many other 12MP cameras. High ISO images are not to the same standard as the lower values but are useable.
Thirdly - The Video. I'm a video novice & approach it very much from the point of view of a photographer. The GH1 is easy to use & offers a level of control which puts other manufacturers to shame. Phillip Bloom is a well-known cameraman and director of photography & he has lots of observations on the GH1 on his excellent website at:- http://philipbloom.co.uk/
COSINA VOIGTLANDER 50mm F/1.1 NOKTON lens.
This lens was one of the first things I wanted to try when the GH1 arrived. I bought it after I sold my first GH1 & was intrigued to know how it would perform on a GH1. I have used it extensively on my M8 & was very impressed.
Ultra fast lenses are something special. People think of f/2.8 zoom lenses as "fast" but this is 2 3/4 stops "faster" than that. In low light if an F/2.8 lens lets you shoot at ISO 1600, this lens let you shoot at ISO 250. If you compare it to an average zoom lens the differences are even more pronounced. An average zoom lens, say an 18-55mm, is around F/5.6 at 50mm. This lens is an incredible 4 3/4 stops faster. If your zoom lets you shoot at ISO 3200 this lens lets you shoot at ISO 125!! The advantages in terms of Image quality are obvious. There is the trade-off of depth of field of course, but many photographers, including myself, see this as an advantage. In some of the places that I work, the opportunity to put, often unattractive, elements out of focus is a advantage. In terms of video, it does help to create that "film" look. Many things shot on video have that flat, everything in focus, look. Watch any movie & you see the use of differential focus all the time, often used in a very creative way.
The 14-140 zoom lens that comes with the GH1 is an amazing piece of technology. I posted some observations on it at:- /soundimageplus/2009/06/gh1-14-140-lens.html
but it as a slow lens, so for many situations a faster lens is required.
I took a series of stills test shots on the Nokton, all at F/1.1. They came out very well. Theres some CA & purple fringing but this goes with territory as far as lenses of this type go. Focusing at F/1.1 needs care but the Manual Focus assist function on the GH1 helps enormously & the ability to use this via the Electronic View Finder (EVF) is another advantage.
I have posted a set of full-size samples at:-http://www.flickr.com/photos/29782425@N08/sets/72157622404603061/
When I get the chance I will shoot some video using it.