if I get a GH4, and just one lens...

[Kevin McRoberts]

Good choice, you can get a lot of mileage out of the 12-35. It's also one of the lenses most able to exploit the GH4s AF technology.

Way back when I first started with my GH2 (and the 12-35 wasn't available), I bought an inexpensive set of vintage OM primes and still sometimes use them for commercials and interviews. Static situations especially can make good use of old cheap glass.

[Joe Ogiba]

The 12-35mm is a great start but if you want the fastest and sharpest m4/3rd telephoto lens the Olympus M.Zuiko Digital 75 mm f/1.8 ED is the way to go. Here is a photo of it on my GH4 :
https://farm3.staticflickr.com/2935/...4283d1ea_k.jpg

[Buba Kastorski]

Originally Posted by Malcolm Hamilton

a softer out-of-focus look

Originally Posted by Malcolm Hamilton

I'd like a lens that lets in lots of light,

Originally Posted by Malcolm Hamilton

and one that might permit me to use auto-focus

Originally Posted by Malcolm Hamilton

I like to shoot a lot of stuff hand-held, and I like to move when I shoot.

Originally Posted by Malcolm Hamilton

I need to be able to seamlessly change exposure as I move around.

one lens won't do all you want, but if i had to choose just one for GH4 i'd pick 12-35 and 35-100 :)))

[Alan Melville]

Originally Posted by Joe Ogiba

The 12-35mm is a great start but if you want the fastest and sharpest m4/3rd telephoto lens the Olympus M.Zuiko Digital 75 mm f/1.8 ED is the way to go. Here is a photo of it on my GH4 :
https://farm3.staticflickr.com/2935/...4283d1ea_k.jpg

Mate, that pic has got some 'pop' to it! What was it shot with? Did you shoot it as a HDR or have you played in post?
Cheers.
Al.