Most long lenses I’ve used over the years were strong on some subject matter and not so strong on others. I can count on one hand the number I’ve used that do everything well, the 90-280mm SL and R 280mm f/4 APO among them.
Such is the case with the Lumix 70-200mm when the 2X is added. It’s very good but not great on some things, but outings the past couple of days have shown it to be not good at all with bird feathers. No problem, as its original purpose in my arsenal was to be used bare, at which it is superb.
The 90-280mm would probably extrapolate to 400mm equivalent better than the Lumix + TC anyway. And it seems to be what I prefer to carry when I head out the door—for obvious reasons. But there will be days when I want more reach—and less weight.
Going through some old files from 2016 I looked at several days’ work with the Panleica 100-400mm and GX8. Turns out it’s the opposite of the Lumix S combo: unremarkable on static targets but near-spectacular on bird feathers. Yes, I know the downside of shooting critters on m43, four-digit ISO as a starting point on cloudy days and noise sometimes coinciding with feather details. Those days are what f/4 on the long end of the SL zoom is for.
Yeah, I know what you’re thinking. And you’re right . . .