Oly vs Panny 46mm filter size/lens cap

Discussion in 'Native Lenses' started by dave92029, Mar 26, 2013.

  1. dave92029

    dave92029 Mu-43 Regular

    May 7, 2010
    Escondido, CA
    I have both the Olympus 60mm f2.8 and the Panasonic 20mm f1.7 lens. Both indicate that they require a 46mm lens filter/lens cap.

    This is wonderful because I bought one Circular Polarizer, which should fit on both lens.

    My question is how come the actual physical lens element on both lens are so different in size, yet they both have the same filter size?

  2. slothead

    slothead Mu-43 All-Pro

    Aug 14, 2012
    Frederick, MD
    The aperture ratio is the ratio of the focal length to the actual lens opening. In other words the lenses of the 20mm f/1.7 has to be at least 20/1.7 or 11.76mm across, and the 60mm f.2.8 60/2.8 or 21.43mm across.