Well, I went outside, found a decent edge, opened the aperture rigt up, and it takes a shot, but only with very slo shutter.
Checked the aperture by closing it down, and then with the DoF preview, and it MADE NO DIFFERENCE. Did the same thing with the 75-300 canon lens, and the aperture closing can be seen clearly when the DoF preview is pressed. So, conclusion, the aperture is not being controlled. It is closed down at f22 (minimum, I think) and doesn't respond when changed on the camera. So, either a communication fault, the lens is not compatible, or there's a mechanical fault with the aperture blades. Any which way, it don't work!
