When I was looking for wide ope Tamron 150-600 G2 shots, it occurred to me: There are some - when the light is bright and the air clear, the sharpness is amazing. After trying to upload some of the yesterday's shots like that one
which is a crop out of DX at f/9 (not really wide open but showing what I like to show), I stumbled in my gallery of Sigma 150-600 Sports.
For occasional shots of birds or small animals Tamron's G2 a great and highly affordable, very transportable lens with some nice touches in handling. It just gets difficult to let it shine in dim light, when ether ISO have to go beyond 4 digits or shutter speed has to go in blurred risk mode. The sharpness remains the same but noise is covering details.
That spider's line with the water drops I just saw afterwards... resolving this detail to me is already more than worth the price. There are a lot offers for Nikon in the range of 500-600 mm.
Occasionally I stumbled into a gallery of my former Sigma 150-600 Sports which was a tad better and five tads heavier - so in "tad relation", I made a good change. But then... because it's so heavy, I used to take a tripod or monopod with me. These remain at home very often although I'm sure the G2 would also benefit from a steadier support.
The pictures might not be comparable, but I still think, if all circumstances work the right direction, the Sigma is better:
So, regarding that lens roadmap of Pentax, one has to be very dedicated to this brand. Don't get that wrong: On the Fujifilm side of things it's worse in long tele. Swallow the 100-400 or leave it... and that lens has handling downsides like focus by wire, not enough tele reach for small birds, aperture ring also by wire and a strange idea about focus delimiter...