OK, I've got the 150mm lens on, and I want to shoot f/4 with a shutter speed of 2 seconds. Except that the lens seems to be fixed such that I'm stuck with f/4 and 1/250 (and f/5.6 is 1/125, f/8 is 1/60th, etc.).

How do I set the aperture and shutter speed independently?

Can you tell I'm a long-time Bronica user?

Thanks -

- CJ