A light but steady rain persisted throughout a three-hour walk this afternoon with the 90D and 100-400mm, a good chance to see how things would look in probably the worst kind of conditions in which I would shoot.
The dim lighting gave diffraction a good opportunity to rear its ugly head, as seen in the detail-less second shot below, taken at f/8 with the extender attached. The camera’s small and dense sensor is diffraction-limited starting at f/6.0.
No issues with the bare lens, though, as it nailed every shot, sharper than a number of primes I’ve used of equivalent focal length. The sensor was as expected, nothing good enough for print in these conditions. Full frame is a necessity on days like these.
And, looking at the EOS R shots with a calmer mind today, I see its value with the lens. Between full frame and crop, teleconverter and bare lens, etc. it sort of becomes like six of one, half-dozen of the other, if that makes sense.
Still no sign of the 100-500mm in these parts (would just like to see what one looks like!). OTOH, the L-mount Sigma has been in the shops here since last Friday. For all the confusion at the moment, I’m still convinced the EF lens was the right choice for me, though . . .