NEX 7, should I worry about color cast on fast legacy primes wide open ??

Discussion in 'Sony Alpha E-Mount Cameras' started by nianys, Sep 10, 2012.

  1. nianys

    nianys TalkEmount All-Pro

    Aug 23, 2012
    France
    Hey guys

    loving my 5N and now strongly considering either 7 or 6.
    I read today something about a magenta color cast when shooting fast primes wide open (basically exactly what I've bought into NEX for, lol).

    How real is this issue ?? Any reason it happens on the 7 and not on the 5N ? Will the 6 suffer the same ?

    Sorry, I'm really clueless about this issue and trying to understand it.

    Thanks !
     
  2. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    It's less an issue of lens speed than focal length & it only happens with rangefinder lenses, so if you're using slr lenses there is no issue.

    The color cast can and does happen on both the 5N and the 7. It is easily corrected using CornerFix.
     
  3. Dioptrick

    Dioptrick TalkEmount All-Pro

    Feb 4, 2012
    New Zealand
  4. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    Senility sucks! I forgot I posted that thread. LOL
     
  5. lenshoarder

    lenshoarder TalkEmount Veteran

    297
    Feb 7, 2012
    I can see how that would be more of a problem with the original NEX 3 and 5, but the C3, 5N and 7 should have the microprism sensors that are designed to compensate for the angle of incidence of the ray at the corners.

    Regardless, fast primes are just inherently soft wide open. Traditionally, it's been described as like having vaseline smeared on the lens. Even back in the film days.

    Some examples how things tightened up even one stop up from wide open.

    Test of the Pentax 50mm f1.4 M42.
    Test of the Olympus 50mm F1.4 OM.
     
  6. Dioptrick

    Dioptrick TalkEmount All-Pro

    Feb 4, 2012
    New Zealand
    The photos with purple fringes on both those links shows pics taken with the Cosina Voigtlander 15mm F4.5 lens - on Bolampau's NEX7 and Bimjo's 5N. I suspect it has more to do with rangefinder lenses whose rear optical element is really close to the sensor. I could be wrong but I don't think purple fringing has anything to do with shooting with wide open aperture.

    Perhaps Bimjo can shed more light on the matter (excuse the pun). :)
    Does your CV 15mm purple fringe in all the aperture settings, Bimjo?
     
  7. Dioptrick

    Dioptrick TalkEmount All-Pro

    Feb 4, 2012
    New Zealand
  8. Bimjo

    Bimjo Super Moderator

    Oct 28, 2011
    Washington State
    Jim
    So far, yeah. Yet I've seen several people with the CV15/5N combo that have no issues whatsoever. I initially thought it might be the lens adapter. I'm using a Rainbow Imaging L39-NEX and somebody using a Voigtlander M-NEX adapter has color shift/vignette as bad as me.

    Must be the way I hold the camera or something. LOL