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Thread: A curious thing?

  1. #1
    Subscriber Member tashley's Avatar
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    A curious thing?

    Being both prone to idle curiosity and by nature inclined to pixel peeping, I decided to test my hypothesis (instrumental in my purchase of a D810) that the D810 with 70-200 F4 was superior at suppressing shutter slap issues when judged against the Sony A7R with FE 70-200 F4.

    I shot a series of handheld shots on both cameras, alternating, at 200mm and at two different combinations of shutter speed, ISO and aperture.

    The second series was shot at a shutter of 100th of a second and, as I suspected, showed a very clearly superior performance from the Nikon. Here is a totally representative pair of frames, one from each camera. Guess which is which:





    So far, so good and very much as I expected: the inability of the A7R to work for shots of this sort has really been cramping my style. Sorted.

    But the next series were shot at F5.6 and 1/320th. This is usually not quite into the safe zone for the Sony, which seems to generally need shutter speeds of 2x focal length even with stabilisation on. However, I was feeling lucky and was able to partially brace against a door frame and in the event the Sony shot worked out to be approximately as free of camera shake as the Nikon. But a very curious thing became apparent as I looked at the files: Both cameras are roughly equally sharp on the central part (the middle 'twin set' of windows, which was also the point of AF) BUT the Nikon frame is softer at the bottom (see the red door and surround) and the Sony is sharper at the top (see the crenellations).

    I have my theories, but would be curious to hear what others think? This effect was replicated across a series of frames,

    BTW one nice thing about the partial return to Nikon is, no more jaggies: take a look at the crenellations and the diamond-shaped ventilation panes in the upper windows in both images.

    Click on each image to load a full sized version:

    Nikon:



    Sony:
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    Re: A curious thing?

    Tim

    Did you use any lens correction on the Nikon shot? I know there is no profile for the camera so I guess any issues with softness can't be properly addressed until the camera is actually supported in the software?

    I will say that the Sony file is horrible, very "digital" in its look and the top as you point out is terrible with the jagged edges and in general looks over sharpened and "lively" for want of a better word.

    I doubt it will be long until the D810 is supported, it already looks a more pleasing shot though than the sony in this situation.

    Mat

  3. #3
    Subscriber Member tashley's Avatar
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    Re: A curious thing?

    Hi Mat,

    I didn't apply any lens corrections to the Nikon file because of the reasons you state, and neither to the Sony files, so as to maintain a level playing field. But I can't see that they would be able to make the soft areas sharper. I agree about the digital look of the Sony, and it was also clear in the comparisons I posted yesterday that the noise pattern in shadows of the Nikon is both less obtrusive and more analogue in feel. Altogether the Nikon has more natural looking files, it's important to point out that these differences largely disappear at print resolutions rather than at 100% on 100ppi monitors...

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    Sr. Administrator Jack's Avatar
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    Re: A curious thing?

    I think you are trying to split the proverbial gnat's eyelash

    Reality is that at these pixel pitches using even smaller apertures like 5.6 or 8, DOF remains so thin and limited that even the most minute focus difference will change the look of overall focus at pixel level view. So yes, the main window is in focus in each frame, but the N file could be biased slightly to rear of that, while the S file may be biased slightly to the fore of that point. Alternatively, one or both sensors may be a micron or two tilted out of perpendicular OR a lens may have a few microns of skew in a single element, and either is enough at these pitches to add an ever so slightly visible Scheimpflug effect in the PoF.

    The shutter vibration is obvious (and significantly detrimental) so you want to avoid that system for that type of work. But for the rest, my advice is it's time to stop the pixel-peeping and go out and make lovely images. With this level of resolution, the most insignificant technical imperfection will probably be visible in the file somewhere.
    Jack
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    "Perfection is not attainable. But if we chase perfection, we can catch excellence."
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    Subscriber Member tashley's Avatar
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    Re: A curious thing?

    Thanks Jack. Those are pretty much the explanations I had in mind and it is indeed an idle exercise. At those and those alone, I excel

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    Sr. Administrator Jack's Avatar
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    Re: A curious thing?

    Quote Originally Posted by tashley View Post
    At those and those alone, I excel
    All of us who share some measure of the OCD complex can relate -- so you're not alone
    Jack
    home: www.getdpi.com

    "Perfection is not attainable. But if we chase perfection, we can catch excellence."
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