Praktica MTL3 35 mm SLR still camera

A completely manual 35 mm SLR camera from the 1980s.  About the only special feature it offers is an internal battery powered light meter.  It's entirely mechanical, even the exposure mechanism is clockwork (it's wound up as you wind the film through).  It doesn't require any power to work, so long as you can work out what exposure to use in some other way.  But it's quite a heavy camera, and does jerk when you fire the trigger, so you need a good grip, or a tripod, to not get blurred shots.  Only a few of the photos on this website will have been taken using this camera.

I only have ordinary 50 mm wide angle and 135 mm telephoto lenses for this camera.  At the moment, you can see a rotatable circular polaroid filter on the front of the lens [a “Hama PL circular M49 (IV)”].  I'm not quite sure why a circularly polarised filter needs to be rotatable, and how that could do what it does (change the response), but that's what it claims to be.  I would have thought, that being circularly polarised, it'd behave the same way no matter which orientation, unlike horizontal or vertical polaroid filters.  For what it's worth, I don't see a major change as you rotate it; nor a major change between having the filter on or off the camera, but I haven't really tried using it under more extreme lighting conditions.