This is an in-camera zoom blur, using the 70-200mm f/2.8. I had an idea that I tried out in this one - tell me what you think. I took two images, the first being the twist of the zoom ring, then made another exposure immediately after that one - this time leaving the zoom static to get a sharp version of the scene at the fully zoomed out magnification. Opened them both in PS and layered them, them masked the sharp layer to only let the flowers show through.










