This lens is known to exhibit purple fringing on DSLR's and when adapted to the Q the purple tendencies are exaggerated.
I do not recommend this lens for the Q in tele mode.
There is a previous test of this lens that shows better results so I may have a different version or my copy is defective.
I tested it in tele mode only, so I am not vouching for its performance in macro mode.
Since this lens has an aperture ring i left the Pentax adapter on the L (lens) setting so I could control the aperture from the lens.
At 300mm this lens is wide open at f5.6, and at that setting the images have a soft focus look with small objects lacking detail with hints of purple fringe through the image.
The lens sharpens up at f8 and f11, but then it exhibits wide purple fringe surrounding the areas of difference in contrast.
To start to remove the purple fringe it must be stopped down to f16, but by then the images lack detail due to diffraction.
Sample wide open
Sample at f8
Sample at f16