Full frame vs. "pseudo Full frame"

Discussion in 'Open Discussion' started by Mellow, Sep 26, 2013.

  1. Mellow

    Mellow TalkEmount Regular

    31
    Aug 18, 2013
    Florida or Wyoming
    Tom
    I posted a question about what constitutes the "full frame look" (because I didn't know) on the m43 forum and got lots of great responses. One thing almost everyone seems to agree with is that FF lenses on FF cameras can produce shallower DOF at greater distances, and that this is a big part of the FF look. So now I'm here asking:

    Can you get that same FF look with a fast lens + focal reducer on an APS-C body like the NEX? If not, why not?

    And: what advantages will the FF NEX offer over this approach? (Beyond the two I can think of: (a) can use RF lenses; and (b) will avoid image degradation due to the focal reducer glass.)
     
  2. dsiglin

    dsiglin TalkEmount Veteran

    230
    Apr 23, 2013
    Greenville, SC
    A larger sensor will give you a shallower depth of field at say 2.8 then a crop sensor at 2.8. That's the only difference I know of when it comes to shallower DOF. Another difference between crop and full frame is better tonal range, better color reproduction (depends on some other things), better low light performance.
     
  3. serhan

    serhan TalkEmount All-Pro

    Aug 27, 2011
    NYC
    When you say FF look, are you talking about portraits, landscapes?

    DOF advantage in portraits might be disadvantage for landscapes. However, as said above FF sensor will give you better dynamic range, color, contrast, high iso, etc. So you can push the photo more to the limits eg crop sensor gets noisy for the same amount of PP compared to FF.

    Using an adapter causes more corner softness. Usually FF lenses has more corner softness as they are more designed for the film age and putting an adapter makes the corners worse. However if you look in pixel detail, FF has always a better sharpness due to bigger pixels so it doesn't push the lens to the limits as a crop camera does, eg you can stop more before diffraction hits.

    Nex FF will have problem with wider rf lenses unless Sony uses the microlenses or a bigger/better designed lenses... From what I read, if the organic sensors used, it will be less problems with corners as it will behave more like film. But so far that sensor is still in the research side. So it is pluses or minuses for both sides and depends on what you shoot.
     
  4. dbmiller

    dbmiller TalkEmount Top Veteran

    778
    Mar 2, 2012
    New England
    Yes. A focal reducer (Such as the lens turbo) on APS-C would reduce the image circle from FF down to APS-C, so the DoF would be nearly the same.
    I believe you are correct here (I read this wrong for an earlier, deleted reply). The disadvantage is that you don't get the extra stop of light the focal reducer has.
     
  5. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Better dynamic range and color? That was the case in the past. However, the differences are currently VERY small. Better high ISO? By about a stop. I shoot 90% of my pictures at or above ISO 1600 and I'm completely happy with the performance of my NEX-5, so my (maybe keen) guess is that most to everyone would be happy with the ISO performance of current APS-C sized sensors. DoF is a very subjective matter, so depending on what you like, either ff or APS-C has an advantage.

    Better sharpness due to bigger pixels? Not necessarily true. Yes, ff cameras pretty much always have bigger pixels. But does that mean better sharpness? I would say no. High end lenses designed for APS-C sized sensors always resolve more lines per mm than lenses designed for full frame, so in most cases you'll get the maximum possible resolution long before reaching the diffraction limit. This means a 24MP APS-C sensor gives you just as much detail and resolution as a 24MP 35mm sensor does if you know what you do, the 35mm sensor is just slightly more flexible in this regard.

    And to address the diffraction limit: Utilizing quantum litography, it is possible to shift the diffraction limit quite some stops above where it usually hits. I'm not yet aware of any consumer camera that uses this technology now, but in the long road, this will give APS-C sized sensors the ability to resolve insanely high resolutions.

    So in the end, ff cameras have huge advantages for people who already own a bunch of ff lenses, but for everyone else, there's not much to get from such a sensor compared to APS-C sensors built using the same technology.
     
  6. Mellow

    Mellow TalkEmount Regular

    31
    Aug 18, 2013
    Florida or Wyoming
    Tom
    Thanks for all the replies. This really has my brain spinning.

    It seems that the biggest advantage of FF is the shallower DOF, which one can indeed achieve with a focal reducer--if the lens is fast. Slow lenses won't speed up enough to make them worth the extra size and weight. For example, it seems there would be no reason to use a 35mm f/2.8 with a focal reducer since I could get the same effect with a native lens like the SEL24F18Z @ 24mm f/1.8. Am I right?

    (well, OK cost might be a reason, but other than that . . . )
     
  7. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    Besides that the 24mm Sonnar is a much higher quality lens than most 35mm f/2.8 lenses I know, you generally get better quality with native lenses. The focal length reducers have some disadvantages (as adding an additional complex lens system to an existing lens always has), and one is worse corner quality than without it. So it's a great option for shallow depth of field work, not such a good one for macro, landscape and similar work where you need every bit of resolution you can get.

    And yes, getting lenses which are f/1.8 or faster will give you the biggest advantage as there aren't any that fast native E-Mount lenses.
     
  8. serhan

    serhan TalkEmount All-Pro

    Aug 27, 2011
    NYC
    Yes, the difference is small enough to recognize unless you print very big and also FF has more potential for to go more MP whether you need or not. Here is the DXO article regarding to perceptual MP:
    http://www.dxomark.com/index.php/en...r-DxOMark-s-Perceptual-Megapixel-can-help-you

    and new lenses produced for FF resolve better then the APSC also:
    http://www.dxomark.com/index.php/Le...ra1)/0/(lens2)/1196/(brand2)/Sony/(camera2)/0

    It is all diminishing rate of returns for higher gear whether you need or not...

     
  9. Poki

    Poki TalkEmount Hall of Famer

    Aug 30, 2011
    Austria
    The 'perceptual MP' rating by DxO is more a believe it or not affair. There's no scientific prove their calculations really lead to the perceived resolution except the claim DxO themselves make, and that's not very convincing.

    As for lens resolution - of course a lens that covers a bigger image circle will resolve better, that was not the point. The point was the ff lens will resolve worse on a certain length of a pixel line on a sensor, which means a lens designed for APS-C sized sensors will always resolve better on APS-C sized sensors than a lens designed for ff lenses. Also, to rate a lens resolution in MP is pretty brave, to say the least.