75mm f/4.5 EF Lens
The 75mm f/4.5 Steinheill Cassar adapted to EF mount. It weighs only 131g, making it lighter than even the Canon EF 50mm f/1.8, the lightest lens Canon makes.
The lens works great on Canon EOS cameras. The cool thing about having a lens with a leaf shutter in EF mount is that you can sync flash at any speed. Just set the camera to bulb and fire the shutter.
Alternately, you can set the lens shutter to Bulb and shoot using the Canon's shutter. Flexible!