>>4468655Ha.
Yeah, I probably should have specified the manufacturer/model.
It's just that after joining the Canon RF cult by getting an R7 I kinda got used to the fact that we get almost zero 3rd party options, so its usually enough to say "RF + <focal distance>" or "RF + <focal distance> + <aperture>" for every fellow cult member to understand what lens I mean.
I'm considering 200-800, but my particular style of birding involves me running around forests/swamps and hand-holding most of my shots. To me, sigma's weight is "almost comfortable" for this task, but a lighter lens without an adapter would be appreciated, and 100-500 is lighter, unlike 200-800.
As for reach, well, I do encounter situations where even 600mm isn't quite enough, but very rarely.
And I'm not sure 200-800 would provide a decent result at such extremes. Sigma already kinda sucks at 600mm, its only real saving grace is the fact that it sharpens up at F8 and F8 is just before the diffraction kicks in on my cropped sensor.
800mm + F9 starting (and ending, lol) + even higher ISO (to compensate for aperture and focal distance) together sound like a recipe for terrible IQ.
100-500 is supposed to be very sharp even at 7.1 all throughout the zoom range, so at the very least I would get two usable apertures instead of one(zero).
As for 100-400, well, its main advantage over everything else is it's weight, but as I've said - I'm almost comfortable hand-holding sigma for prolonged periods of time, so I'd rather just stick with it instead.
Frankly, all options seem like sidegrades with many trade-offs, even the very expensive 100-500.
The dream would be someone like Sigma (the only manufacturer that cares about RF-S mount, unlike fucking Canon) producing their own super telephoto lens designed for APS-C.
Maybe I should just keep using my old sigma and praying for that.
