I am shooting video on GH1 with lenses from old 16mm movie cameras; primarily in C mount, some Arri mount.
I am trying to determine the FOV of my lenses in 35mm lens equivalent terms, and I'm stumped because of the way different lenses crop/don't crop on the m4/3 sensor.
Lenses _< 25mm tend to vignette on the sensor. So these don't have a crop factor, right? (or do they have a negative crop factor?) I am seeing more than what the lens was designed to show. So is a 25mm lens then really giving me the FOV of 20mm?
Lenses > 25mm don't vignette. So 50mm, 75mm, 150mm lenses have full coverage. It is said that the GH1 has a 2x crop factor, but I believe that is for 35mm format glass? These lenses were all designed for regular 16mm or super 16mm format. Yet they are not vignetting like the 25 and below. Still, with m4/3 larger than 16mm format -- does it mean my 50mm lens is giving me the FOV of a longer, 55mm? Or 50mm? or wider? 45mm? 40mm?
How can one know/measure/ascertain this crucial data??