Originally posted by Rich_A My primary focus will be wildlife, both large and small types out in the wilds (National Parks, primarily).
I have the DA* 300/4 but not the 100-300.
Now, there are people here who love the 100-300 and compare it favorably to the 300.
In your situation my reasoning would be this. The only problem with my DA* 300/4 is that it's not a 400mm or 600mm. For wildlife and especially birding it is just not long enough. I don't want to carry around that other 100-299mm because I want the 300mm or even more, if that makes any sense. Now, I kept my K10D when I bought the K20D so when I'm out in the woods I keep the 300/4 on the K20D and whatever other lens on the K10D, but if I only had one body I'd still go for the prime, but that's just me YMMV.