I’m the lucky owner of both Canon’s RF 800mm f/11 and RF 100-500mm f/4.5-7.1L lenses, so I thought it might be interesting to compare them out in the field, using the Canon RF 1.4x teleconverter to make the 100-500mm a 700mm f/10 lens at the long end. So I packed them up with my R5 and headed to Dutch Gap, one of my favorite birding hikes in the Richmond VA area.
Here you can see the resulting images, and judge the comparative image quality for yourself! As I say in the video up above, the main differences are in price and usability. The 100-500mm L glass is obviously much more expensive, but the benefits are versatility, weather sealing, faster and full-frame autofocus, MUCH shorter minimum focusing distance, and of course the wider (and variable) aperture. But if you want a relatively light and inexpensive option for wildlife photography, you can do a lot worse than the 800mm f/11.
A third option (not tested here, sorry) would be the RF 100-400mm f/5.6-8–price-wise, that’s the cheapest long telephoto currently available, though adding a teleconverter would bump it above the price of the 800mm alone. With the 1.4x TC, it would become 560mm and f/11 at the long end, quite a bit shorter (and no faster) than the 800mm. A 2x TC would get you 800mm at f/16, which is obviously not ideal for anything but bright daylight.
I should note that the 800mm can also use the RF teleconverters, so the 1.4x would make it 1120mm and f/16. I didn’t try that on this excursion, maybe next time!
This was a fun exercise! My conclusion is that the 800mm f/11 does hold its own in terms of image quality, but it definitely has drawbacks in terms of usability and versatility. The 100-500mm is a fantastic lens that offers lots of benefits, and still looks fine even with a teleconverter in the mix–but all of that comes at a hefty premium, price-wise. I intend to hang on to both, with the 800mm mainly seeing use when I know I’ll be shooting distant birds and wildlife.
Thanks for coming along!