Can anyone help me with this. I have come across 3 large format lenses for 14.99 at a thrift shop. They are very weird, it seems as thought they have mirrors attached to them, behind the rear/front elements totally blocking any light from coming through the lens. There doesn't seem to be an obvious way of removing them. What's the deal? Really fancy lens caps or somthing, are they two way mirror filters which let in a very small amount of light, I can't figure tit out. I should mention that they are barrel lenses, and have working apertures, but no aperture scale which tells you what f stop your at. Thanks! I'll ad some pictures later