Sigma 10-20 - Aperture Control

Discussion in 'Adapted Lenses' started by Revrock, Oct 15, 2013.

  1. Revrock

    Revrock TalkEmount Rookie

    Aug 7, 2013
    Hi guys, want to say first that this forum is really great. Lots of friendly people and good info.

    So, I've got a cheap EOS to NEX adapter without an aperture ring, if I buy the Sigma 10-20 Canon mount, how does the Aperture work?

    I have a Canon 50 1.8 that I set the Aperture down to 1.8 in my Canon EOS body and leave it at that.

    How does it work on a zoom lens?

    *I tried testing it out with my 18-55 kit lens, setting it to 3.5 in my EOS body and as I zoom in the exposure doesn't change. Does that mean the Aperture is fixed at 3.5 all the way through the focal range? What can I do without buying another adapter with an aperture ring? I suppose I'll have to look into that.

    I'm just curious as to the inner workings of the camera and lenses in this situation. Thanks for any info.
  2. Bugleone

    Bugleone TalkEmount Veteran

    Aug 21, 2011
    This came up last week and I posted basic details of the three types of canon EF adaptor, namely; comlpletly mechnical where you use EOS body to set aperture.........electronic adaptor which works the lens like EOS body.........and, hybrid type that has it's own iris diaphragm (set to largest aperture then use adaptor for some degree of aperture variation)

    Canon EF is about the worst lens type to use with NEX as far as I can see.

    I would be very interested to know how the sigma 10 to 20 performs on NEX...there have been two(at least) models of this lens and sigma have steadily upgraded the optical perfomance.

    *I assume your canon zoom kept the same aperture since no electronics were present...on zooms which change aperture during zooming I would think this takes the optical perfomance into 'rough ground' since EF has to have elecronics to change aperture...but I maybe wrong!