I don’t think I’m exaggerating because as you can see in the following image and in the 100% crop below, the lens turns out amazingly sharp for a super-tele-zoom. But only if you do everything the right way.
Doing everything the right way means shooting with lots of light. This will make shorter exposure times, which are essential for a lens of such a long focal length and for bird photography in particular, possible. It’s also important to stop down a bit – the picture above was taken with an f/8 aperture, which improved the image sharpness a tiny little bit. You shouldn’t forget that the SD1M demands a lot from lenses due to the high pixel density. 15MP don’t sound like a lot, but when converted to a full frame format this corresponds to a resolution of 33MP!
Possibly the photo may have turned out even sharper if I had increased the sensitivity level to ISO200, which would have allowed an exposure time of 1/800 s instead of 1/400 s. But for me a noiseless rendering was more important than the last bit of sharpness.