Originally posted by DanielT74 I guess it was a hard one - not sure if anyone here owns it (and I don't either unfortunately).
It is a well-known lens but not for this type of work.
unless you did something special with the image, like cropped it. the dimensions do look odd.
I only assumed that this lens might be for birding focal length and judging it was for wildlife which would require distance. also the DOF has something to do as well.
if not, it could be something around 200mm. 135mm would be just too short for such a bit shallow DOF I think and too close for wildlife.