. . . mm, that is.
With no ETA for the RF 100-500mm on the horizon, exploring potential alternatives has me wondering if it would even have enough reach after having become accustomed to the 600mm f11. Quickly ruled out was the 100-400mm IS II+extender, after seeing a video comparison with the 100-500mm using magnified samples that included some Aussie species I’ve shot before.
Past experience with the 800mm f11 tells me, good as it is, the MFD is too long for me. The notion of a good secondhand copy of the 400mm DO II crossed my mind, but it appears that people who buy them keep them, no surprise. Beyond that, seems that there’s nothing to do but wait . . . and get more accustomed to 600mm.
Out with the 600mm and trying the 1.4X again on some Little Terns in flight in gloomy (what else?) weather, the combination could track but couldn’t quite keep up, yielding some almost-but-not-quite shots. It missed a few shots on still birds as well, and didn’t capture much detail when it did focus correctly.
Low light, diffraction, whatever . . . the extender will likely get a rest until some faster glass arrives. Could be a long rest . . .