[Frameworks] BOLEX H16 "Super 16mm" lens options.

[David Tetzlaff]

Mark:

You didn't mention whether your Bolex is reflex or standard. I would assume that if you have a c-mount adapter, your Bolex is a late model bayonet mount with a reflex finder.

Be aware that reflex Bolex cameras require special lenses that figure for the diffraction effects of the beam-splitter prism. While these lenses have the same thread as a C-Mount, they are not properly referred to as "C-Mount" because that label also designates specific back focus characteristics. Thus, the Bolex reflex lenses are "RX Mount". AFAIK, only Kern ever manufactured lenses in this configuration, and it's highly unlikely that any of them would cover a Super 16 frame. 

In general, lenses made specifically for 16mm movie cameras will rarely cover Super16 at all apertures, or at all focal lengths for zooms. The focal length at which a zoom begins to vignette will depend on the design of the lens though.(It won't always be 24mm).

However, the C-mount spec was used by other kinds of cameras, some of which hard larger image areas than 16mm, so some C-Mount lenses will cover Super 16. The most common of these are lenses made for C-mount video cameras, both primes and zooms. These are generally less expensive than 16mm lenses as the optics are considered inferior. But I'd say Canon TV lenses are pretty good, all things considered.

The thing is, when you put a true c-mount lens on your reflex Bolex, the image will blur when you open the aperture to f3.2 or wider:
http://www.city-net.com/~fodder/bolex/truth.html
No problem with longer lenses that are typically slower than that, but you'd lose the whole last stop of that Schneider. 

I know c-mount lenses can be collimated for use with Bolex reflex H16s, but I'm not clear on whether that makes them optically equivalent to RX lenses, or involves some measure of compromise. I do believe that's what most folks with Super 16 Bolexes wind up with though. I also have no idea what getting a lens collimated costs, or whether zooms present more problems than primes.

I believe Bernie at http://super16inc.com could answer any questions you might have about acquiring and/or adapting lenses for your camera...