Anyone experimented with these things? Looking at them and telephoto zooms for some high distance butterfly photography.

I'm guessing you'd have to go MF and learn to work in suitable distance. From what I read about them, they decrease actual stated aperture, and introduce some softness around the corners. So, slower speed, but you gain reach. Would handholding be feasible, or you'd have to go and look even more like a retard to normies running around with a tripod? Main question: On which side of the zoom lens you'd get better magnification? On more extended one, or on narrower one?