You might want to consider how heavy that Canon RF 200-800mm f/6.3-9 IS USM actually is before hiking Montana. Its a beast. I would suggest looking for a used Canon RF 100-500mm f/4.5-7.1 L IS USM instead because it handles the R7 sensor way better. Be careful with f/9 on that 800mm though... it gets noisy fast when the light drops.

Regarding your logic on the 200-800... i really wanted it to be the one, but it was such a letdown in practice. I took one out for a week and the f/9 aperture at the long end was a nightmare on the R7 sensor. As soon as the sun wasnt directly overhead, my ISO spiked and the images looked like oil paintings because of the noise. It just felt flimsy and unreliable for a serious trip. I've learned to be way more conservative with my gear choices lately:

• Avoid the Canon RF 200-800mm f/6.3-9 IS USM if you plan on shooting in anything but bright noon sun.
• Stick to L series glass like the Canon RF 100-500mm f/4.5-7.1 L IS USM for that R7 sensor. Honestly, id rather have a sharp 500mm shot i can crop than a blurry 800mm mess. Montana weather is unpredictable and you need gear that wont fail when the clouds roll in. Save up a bit more or find a used deal because the cheaper reach just isnt worth the headache.

> my logic was the rf 200-800 for the extra reach but then i thought maybe the 100-500 is sharper? Jumping in here... I havent spent a ton of time with the 800mm yet, but I keep seeing reports about how it behaves on the R7 specifically. Since that sensor has such a high pixel density, you gotta be careful with diffraction. IIRC, the R7 starts to soften up once you go past f/7 or so. If youre shooting at f/9 on the long end of that zoom, you might find that you arent actually getting sharper shots even though you have more reach. Its a weird physics trade-off. Not sure if this is 100% true for every copy, but I think the autofocus motors in the 100-500 are a higher grade. For fast moving wildlife like hawks, that acquisition speed is everything. I also heard from a buddy that the 100-500 takes teleconverters okay if you eventually need more range, tho it makes the lens physically longer when zoomed out which can be clunky. In Montana, youre gonna be dealing with some harsh shadows in the mountains or low light during the best animal activity times. f/9 is pretty dark for that. Basically, you gotta decide if you want the raw distance or the better glass quality. That old 75-300 you have is pretty much the bottom of the barrel, so literally any move you make here is gonna feel like a massive upgrade. I think the 100-500 is generally considered the more professional choice for that specific sensor, but the reach on the 800 is tempting for sure. Just something to think about before you drop the cash.