Some test shots on hummingbirds with this lens wide open in f/4.5 in using the lens alone without the gun stock. This lens is the most difficult lens that I have used
- Due to blades in manual diaphragm, I can't confirm focus at f/8.0 and bigger apertures.
- The focusing knob is underneath the lens barrel.
- The preset ring serves as a cocking mechanism for the lens.
- Once cocked, the aperture is wide open, slighter wider than f/4.5, maybe f/4.0, and I can focus but the catch is having to rely on the gun trigger to stop down the lens
- Without the gun stock, I can still stop down by tapping the diagram release bar underneath the lens barrel