I'm a big fan of large aperture lenses for portrait photography.
Unbeknown to many, projection lenses for 35mm or 70mm projectors offer great alternatives to the typical "portrait" lenses. Most of these lenses cover 35mm full frame or MF digital backs with ease at portrait distances. At times these lenses will cover Polaroid pack film or even 4x5 with some vignetting.
When I got my hands on a Bausch & Lomb Super Cinephor, 6" F1.8 my heart started racing ... 152mm at f1.8 on medium frame 645 is nothing to sneeze at.
These lenses of course don't fit any full frame or medium frame camera, so a minimum amount of modification is required. Luckily, most components are readily available on-line from a number of individuals that machine the necessary parts.
So after filling the right lens adaptor for my M65 helicoid mounted on a M645 lens mount, I was in business.
As one can see, this lens is massive. No, there's no iris, one always shoots wide open. An iris could of course be made to fit inside between the elements but that's a major undertaking that I might attempt when I run across a suitable iris and can get some shop time on a CNC and lathe.
I mount and test lenses on my Mamiya 645AF but I typically shoot on a Phase One 645D in studio or Mamiya 645 AFD II on the road with a Leaf 10 digital MF back. I do keep the 645AF for occasional film shooting ...
Below are 4 images shot with the Super CinePhor 6", F1.8 and the Phase One 645D camera. All images print 32" wide, cropped vertically to suit the esthetic.
I elected to represent the images in black and white as these projector lenses are coated with a color correction for 35/70mm film. Great for cine effects but not necessarily everyone's cup of tea for accurate skin tones.
Focussing is a bit challenging because of the shallow depth-of-field, but as one can tell in the above image, it is possible to have "sharp" contrasted by an amazing bokeh. The image above was lit with a 12" Fresnel with a LED spot in it.
The helicoid extension of this combination is excellent to yield almost macro images. Again, focus requires some getting used to and keeping the camera still is no sinecure ... this is one heavy lens and I fully intend to add a Arca style plate to the lens so I can mount the lens/camera combo to a tripod for more controlled work.
Regardless of the challenge, the bokeh is exquisite and the shallow DOF allows for creative composition.