Resolution and lens quality

divamumdivamum Registered Users Posts: 9,021 Major grins
edited August 22, 2010 in Cameras
Question: why is it that higher pixel-density cameras benefit from maximum-quality lenses, and also show up softness/flaws in otherwise great glass? Since moving to the 7d I've noticed that shots out of my 135L just look better and better, while shots from (for instance) the wide end of the 50mm 1.4 seem softer than they did on the xsi. I've read this is typical, so just wondering how and why that works....

Thanks in advance! :thumb
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Comments

  • QarikQarik Registered Users Posts: 4,959 Major grins
    edited August 17, 2010
    Higher qaulity glass can have such sharpness that it's basically limited by pixel count (ie the MTF line is above teh nyquist freq)..ie your camera body. As far as bringing out flaws..not really sure on that one. If sharpness isn't great to begin on a lens with then adding more pixels may only resolve more of the out of focusness?
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  • insanefredinsanefred Registered Users Posts: 604 Major grins
    edited August 17, 2010
    I notice this too.
    With my Nikon D50, I loved my 50mm 1.8, then I upgraded to the D300. I was very surprised to see a lot more softness and purple fringing at 2.8 or faster. But my 24-70 didn't have any problems. Then when I got my D700, the 50mm 1.8 great again and seems very sharp at 1.8 again. And yes, I did make sure I was focusing properly.

    I do see this on all cameras that have more than 10MP (crop sensor), the more resolution, the more picky the camera gets. Some glass that you'd think would be great, gets soft. Some glass you'd think to fail, doesn't. But it all depends.
  • studio1972studio1972 Registered Users Posts: 249 Major grins
    edited August 18, 2010
    When viewing at 100% you are "zooming in" more with a 18mp image that you would be with a 6mp image, so you see more flaws in the lens etc, it's not that the lens is any worse, just that your ability to pixel peep has increased!
    Sarah McDonnell Wedding Photography - Wirral, Liverpool, Cheshire & Manchester
  • divamumdivamum Registered Users Posts: 9,021 Major grins
    edited August 18, 2010
    Richy, no ff comparison for me - I've been on a cropper since I moved to digital and I wasn't shooting at this kind of technical level when I was using a film camera, so the difference wasn't really that big a deal to me; while I covet FF now for its stupendous ISO performance, I've been very happy with the Canon 1.6x cameras I've used and don't see myself going FF unless/until I get some kind of amazing financial windfall................. mwink.gif

    All the comments above make perfect sense and absolutely answer my question - tx all for chiming in. I've wondered this in the past whenever I've read it, and now that I've been experiencing it to some degree wanted to understand it better! thumb.gif I think you've really nailed it as far as things like 1.4 on the 50mm - that's pretty much exactly right!! In fact, I'm trying to get myself into the habit of checking my photos not only at 1:1, but also at 1:2 (and sometimes even 1:3) so that I can get a more "realistic" sense of sharpness and detail. I'm never going to share or print pictures at 100% resolution, so I find it kind of meaningless when the pixel-density is this deep.
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  • NeilLNeilL Registered Users Posts: 4,201 Major grins
    edited August 22, 2010
    divamum wrote: »
    Richy, no ff comparison for me - I've been on a cropper since I moved to digital and I wasn't shooting at this kind of technical level when I was using a film camera, so the difference wasn't really that big a deal to me; while I covet FF now for its stupendous ISO performance, I've been very happy with the Canon 1.6x cameras I've used and don't see myself going FF unless/until I get some kind of amazing financial windfall................. mwink.gif

    All the comments above make perfect sense and absolutely answer my question - tx all for chiming in. I've wondered this in the past whenever I've read it, and now that I've been experiencing it to some degree wanted to understand it better! thumb.gif I think you've really nailed it as far as things like 1.4 on the 50mm - that's pretty much exactly right!! In fact, I'm trying to get myself into the habit of checking my photos not only at 1:1, but also at 1:2 (and sometimes even 1:3) so that I can get a more "realistic" sense of sharpness and detail. I'm never going to share or print pictures at 100% resolution, so I find it kind of meaningless when the pixel-density is this deep.

    Dunno, dm, if I'm talking sense here, but... sensor resolution and lens circle of confusion work together to produce sharpness quality. Further, the larger the sensor the less enlargement required for prints of a particular size, another factor keeping the circle of confusion below the threshold of perception. What you see on your monitor is not the same as what you see in a print. Pixel peeping on your screen is of limited usefulness, but the most convenient guide to the potential iq of a printed digital image. So, those three factors of sensor resolution, lens coc and amount of enlargement required for viewing distance are interrelated in producing your experience of sharpness, and the relationship between them varies with variation in their values, eg from one sensor to another, or from one lens to another. Consequently perceived sharpness will vary.

    Hope someone will shoot me down.:D

    Neil
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