C-Mount CCTV Lenses - 1/3" or 2/3"?

Discussion in 'Adapted Lenses' started by beameup, Jan 15, 2014.

  1. beameup

    beameup Mu-43 Regular

    104
    Oct 23, 2013
    I was wondering about recommendations and information about C-Mount lenses.
    I would like to get a very wide angle (circular image) lens for my E-M1.
     
  2. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    Fred
    EDIT: I just re-read your post and realized you want a circular image. I'm not sure if 2/3" will give you a small enough circle, but it won't be a fisheye if that's what you're looking for.

    You want a lens for 1" sensors. Even that will probably vignette with a wide angle.

    Fred
     
  3. Pawel D.

    Pawel D. Mu-43 Regular

    45
    Jan 25, 2014
    BiaƂystok, Poland
    Umm... I don't exactly know what you mean, but I can just imagine.
    If you would like a fisheye-alike image, I used to use a 14-45 Oly KIT lens with Beroflex "MultiWeitwinkel-Vorsatz". At 14 mm it gave me semi-fisheye effect and strong vignette or should I'd rather say black circle. Zooming in reduced the circle.
    It was exactly this effect (I know it's poor shot, but that's the one I could find quickly and... it's not mine :p ):
    _4129088.JPG
     
  4. beameup

    beameup Mu-43 Regular

    104
    Oct 23, 2013
    I don't want to buy the wrong CCTV lens. I don't understand the difference in the 1/3" and 2/3" varieties of CCTV lenses.
     
  5. fredlong

    fredlong Just this guy...

    Apr 18, 2011
    Massachusetts USA
    Fred
    Old vidicon tubes were sized by adding up the size of two sides. The convention has lasted into the digital age. So for a 1/3" sensor a long side and a short side add up to 1/3". The sensors were all 4:3 like a television screen. A 1" sensor is a little smaller than a 4/3" sensor.

    Most lenses meant to cover a 1" sensor will cover or almost cover a 4/3 sensor. Wide angles usually vignette more. I'm not aware of any inexpensive fish eye video lenses. You may have better luck with a fish eye auxiliary lens. Something like a .2x will give you a circular fish eye look on a normal to moderately wide lens.

    Fred