I just got a Vivitar 200mm f/3.5 M42 lens. I wanted to test and see how it performed against my other 200mm lenses (mostly zooms). So I setup my tripod and took a few shots of a melting paw print on my front porch at roughly 7' away.
Once in Aperture I noticed something right away... Some lenses at 200mm had the same FOV as my 135mm prime (and the DA* @ 135).
I always thought and was always told that even the new "for digital" lenses had their focal length measured as the 35mm equivalent even though the actual length will be 1.5x larger. A 200mm will be a 300mm on a crop sensor and a 50mm will be a 75mm on a crop sensor...
But after those test shots, my Sigma and Tamron zooms at 200mm both look like my 135mm Deitz (film era) and not my 200mm Vivitar... and 135mm x 1.5 = 202mm. Are these lenses focal length measured for APSC?
The DA* seems like it is correct if you compare to the film era prime (135mm)
I can understand seeing some slight variation between brands and lens series but look at the shots below...