Quote Originally Posted by jev View Post
Size doesn't really matter, weight: as low as possible but would prefer to keep a "daily set" under 2 kg in total (body + lenses to cover 24 to at least 400 mm). IQ must be good enough for high-gloss publications at A3 format. On the long end, I do not need to cover everything, one or two fast long primes would be good. Image stabilization would be more than just nice to have on the long end (I hate using a monopod!).
Don't confuse 4/3 and micro 4/3. The sensor sizes are the same but there hasn't been an updated 4/3 DSLR with a modern sensor. On the other hand, virtually every micro 4/3 camera these days are using the latest generation sensor. Much better than before but you have to be realistic. It is still 1/4 the size of a full frame sensor after all.
Anyways, An E-M1 with 12-40/2.8 and 40-150/2.8 + TC will get you 24-300mm equivalent FOV at 2.8 (light gathering) and 300-420mm @f4 (light gathering). This kit should be roughly 2kg if I remember my figures correctly.

Quote Originally Posted by jev View Post
Most pro's I talked to while working on the PGA tour events use a 500/4 on an APS-H camera. Personally, my longest is a 100-400/4.5-5.6, not very fast but on a full-frame camera still adequate to throw objects in the background completely out of focus when shooting on the course. It's a bit on the short side though and when the competition-leaders get to the final green I switch it for my trusty 70-200/2.8 (often busy crowds in the background, low light but no need for length).
You'' want to look into the upcoming Olympus 300/4 that gets you 600mm equivalent FOV. F4 light gathering capabilities but f8 like DOF on m43. But to honest, at these sort of focal lengths you really don't need a very large aperture to throw things out of focus in the background.
One advantage to mirrorless cameras are that, they are mirrorless. And hence no mirror slap. So you should be able to shoot quieter on the golf course. Of course you could use live view on DSLR to match this ability. But some mirrorless models eg. Nikon V3 can be completely silent using the electronic shutter so you don't disturb the golfer.