3 ACCEPTED SOLUTIONS
I own and love both the RF100-400 and RF100-500 for two very specific and different reasons. The lightweight inconspicuous 100-400 is my go to for street photography, traveling light, or stationary birds or objects.
The 100-500 is big and gets noticed but it's autofocus and tracking is immeasurably better than the 100-400 so it's a must for me for airshows, flying birds, fast anything. It's not as big and heavy as almost any of my old EF zooms but it's a beast compared to the 100-400.
Lastly there's the price... Considering how amazing the 100-400 is for the price I almost always recommend starting there unless you have some professional wage earning justification for the 100-500. All of my lenses have paid for themselves so I don't hesitate to get anything that fits a need but 69% of the time I can't tell the difference between shots on either lens. The 31% where you can see the difference is significant if you need fast panning or exquisite bokeh with the 500 so you have to decide if that's worth the extra $Gs.
I've attached some street photos with the 400 from New Orleans where I was barely noticed and some airshow work with the 500 (and a humming bird with the 500 to show the bonus bokeh that the 400 wouldn't pull).
Can't go wrong with either and now you know how and why I use them, happy shooting!
*All with R7
