I am truly amazed at the ratings for this objective and specifically about his dive.
300 mm it is very very frustrating clutter and ..
Having had for 1 year the 300 mm F4, the day and night here do not expect to count the hairs or observing feathery fluff
inflated by the wind ((see photo, I was about 15 m)
between 80 and 135 mm in portrait it is actually good to see good.
astonishment on a moon in focus mode, it is good
no it is not bright, 5.8 do not dream at 300mm it will either wait very sunny hours either mount iso
and much work to be performed under lightroom (see photo)
more noisy (annoying with birds) and do not always hang properly.
For its price it is the bare minimum, if the photos are regradées on a screen but to have a Sigma 18-250 eos100D mounted on a gun, it is not as good.
not the same budget but I'll slip on the 60-250 mm