TLR AutoPolariser

Despite being 2006 currently, I find I'm shooting film not digital on my Yashica Mat-124G (and sometimes my Mamiya C330). The Mat has, in common with many highly desirable but unfortunately now quite aged TLRs, a bayonet filter fitting for both the viewing lens and the taking lens.

This has a slight disadvantage with polarising filters in that one can't easily see whether you've adjusted the polarising direction appropriately (and of course, in some scenes, this might not be the obvious 90° to the sun direction).

Now, I'm not the only photographer shooting on vintage TLRs. This idea is a proposal for an automatic polarising filter, which fits on the Bay-1 bayonet on the front of the lens. It consists of a simple autofocus-like assembly (typically a driven helicoid) but instead of focus, it's rotating the polariser for maximum cut effect, ie, maximum polarisation effect. Thus, the autopolariser can be relied upon to try and find the 'best fit' angle of rotation, where possible, even though you can't see the result (unless it was a paired autopolariser). The exposure reduction factor could also be read out, as in sampling the result of the polarising effect, it could also act as a more precise exposure meter than those of the day.