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A7M2 & XT-1 Exposure Comparison

Discussion in 'Sony Alpha E-Mount Cameras' started by dmward, Apr 16, 2015.

  1. dmward

    dmward TalkEmount Veteran

    200
    Mar 21, 2015
    Metro Chicago
    David
    Since there has been quite a bit of discussion about camera exposure and ISO accuracy brought about by my thread about a gig I shot recently with both a Fuji XT-1 and a Sony A7M2 I thought I’d pick an image from each camera, same subject, same lighting, shot relatively close together in time and see what the camera settings were; what would have to be done in Lightroom to make them nearly identical and what impact processing has one the images.

    Here are the two images with no processing other than exposure and white balance:

    This is the Fuji image. Camera setting were ISO 3200, 1/60 at F 2.8. White Balance was set by using eye dropper on the white portion of his tee shirt under his chin. (2600, -8) Exposure was increased 1 EV.

    [​IMG]

    This is the Sony image. Camera setting were ISO 6400, 1/30 at F 4.0. White Balance was set by using eye dropper on the white portion of his tee shirt under his chin. (2550, -8) Exposure was left at 0 EV.

    [​IMG]

    The two images, in my view, look close in exposure. The reading in Lightroom on the white tee shirt where the white balance was taken is 85% for the Fuji image and 84% for the Sony image once they were adjusted.

    The Fuji image looked underexposed before the adjustment. The Sony image looked properly exposed. Interestingly, increasing the Fuji image 1EV is the equivalent of either slowing the shutter to 1/30 of a second, the Sony shutter speed, or increasing the ISO to 6400, the Sony ISO setting. The Sony required both the higher ISO and the slower shutter speed to compensate for the F4 aperture.

    Image quality, difficult to accurately determine in these smallish JPGs is comparable. I set sharpening and noise reduce to 0 so that the native sensor characteristics would show.

    Here are 100% crops of each to show the similarity in digital grain with no noise reduction or sharpening applied.

    Fuji:
    [​IMG]

    Sony:
    [​IMG]
     
    • Informative Informative x 3
  2. tomO2013

    tomO2013 TalkEmount Veteran

    375
    Dec 11, 2014
    Not to nitpick but 1/30 of second shows a little motion blur in the Sony shot so hard to truly evaluate. I'd probably set a minimum shutter speed of 1/60 for such and just bump the ISO.
     
  3. dmward

    dmward TalkEmount Veteran

    200
    Mar 21, 2015
    Metro Chicago
    David
    Tom, for these purposes the blur isn't an issue.
    I found this image in the reject folder. :)
    I did move the shutter speed up a stop and then pushed it in Lightroom for other shots.
     
  4. bartjeej

    bartjeej TalkEmount Rookie

    23
    Oct 8, 2014
    Interesting. So the basic conclusion, if I'm not mistaken, is that both cameras seem to be stating their ISO at about the same levels (whether that's the correct level for both or overstating for both we don't know).

    For ultimate certainty it'd be best to have a static, consistently lit scene, and the same lens on both cameras (since light transmission, or T stop, is often not the same as the F stop, and the difference between T and F stops varies from lens to lens).
     
    • Agree Agree x 1
  5. dmward

    dmward TalkEmount Veteran

    200
    Mar 21, 2015
    Metro Chicago
    David
    That test could be accomplished. However, in my view its an academic exercise. I used the two cameras together shooting the same event. I used each camera's meter to get the best exposure for the camera. Since the lenses were one stop apart in max aperture I used the shutter to keep the ISOs at the same level. Now I know that I can keep the shutter speed up and let the ISO float without a major concern. The dark appearing files in Lightroom is a Fuji anomaly that has no impact on final image quality.

    I'm happy. When I was a young photographer we had 3 Nikon F bodies, 2 hasselblad bodies with 4 lenses, view cameras with multiple lenses, Rollie TLR cameras, and I had two Leica M4s for my personal cameras. We also had 3 Sekonic selenium cell incident light meters. That kit resulted in at least a dozen different shutters and the 3 light meters. We were happy if we were within one stop between cameras or leaf shutters with the same meter.

    From that background the situation with the Fuji and Sony kit variations is a walk in the park. :)
     
  6. pbizarro

    pbizarro TalkEmount Veteran

    349
    Nov 24, 2014
    Portugal
    This is the Fuji image. Camera setting were ISO 3200, 1/60 at F 2.8.
    This is the Sony image. Camera setting were ISO 6400, 1/30 at F 4.0.

    So the Fuji was "underexposing" by 1 stop (1/60 at F 2.8 is the same light as 1/30 at F 4.0), since the ISO was lower.

    Hardly surprising, since different cameras, sometimes even from the same system, will meter differently, according to their exposure algorithms.
     
  7. DigitalD

    DigitalD TalkEmount Veteran

    352
    Mar 2, 2014
    Miami
    David K Fonseca
    It is interesting. I notice with the EM5II it seems to over expose easier compared to the EM1 or the Sony a7. I tend not to mind it too much but its good that I know because if I need mood I know I have to turn down the exposure readings a bit more then usual.

    Always good to know your equipment and how it might perform for you.