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Thread: A900/A850 clipped blacks

  1. #1
    hornblade
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    A900/A850 clipped blacks

    (I have an A850, but lets assume it behaves similarly to an A900 for now).

    I read the monster thread on the optimal ISO (200 vs 320) for the A900. If I understand correctly, ISO 320 is the lowest ISO that doesn't clip blacks. You give up a bit of dynamic range and slightly increase noise with 320, but some people view it as a worthy tradeoff to avoid clipping.

    My question is this: how can I tell if am actually clipping blacks? In Lightroom and Raw Developer I usually start by adjusting black level and exposure to a point where I see no obvious clipping in either blacks or highlights, then make further adjustments to the image. I'm new to the A850, but I've shot a bunch of images at both ISO 320 and ISO 200 and I haven't ran into a case at either ISO where I felt like blacks were severely clipped (except for totally underexposed images).

    Am I missing something? Are my raw converters lying to me about black levels and there is clipping happening that I don't see? Really curious to hear everyone's thoughts -- I want make sure I'm not missing something obvious.

  2. #2
    Senior Member Quentin_Bargate's Avatar
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    Re: A900/A850 clipped blacks

    I find ISO 320 a bit too noisy for general use if a lower ISO can be used, so I can't really say. ISO 200 seems to be optimum, although ISO 100 is fine where you need to use a lower ISO in a studio, for example.
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  3. #3
    hornblade
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    Re: A900/A850 clipped blacks

    Thanks Quentin. From what I've read, ISO 100 is the same as ISO 200 but just meters differently, so there's not an advantage to using it over 200.

    Any thoughts on the clipped blacks problem?

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    Senior Member edwardkaraa's Avatar
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    Re: A900/A850 clipped blacks

    Please don't get me wrong, but I've never really understood this digital age obsession with clipped shadows. I can undersand clipped highlights though, they do look ugly when they're not intentional. That is why I metered for the highlights during 20++ years of using chrome film, and let the shadows take care of themselves. Now I still shoot exactly the same with the A900, by watching the histogram carefully so that I avoid burnt highlights (unless they need to be like specular lights in the frame) and I couldn't care less about the clipped shadows unless there are some important elements there, in which case, I meter for the shadows

    The A900 has the most film like rendition among all DSLR and I would forgive it if it would clip more shadows than others.
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    Senior Member douglasf13's Avatar
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    Re: A900/A850 clipped blacks

    I believe (and Andrey, aka hardloaf, can correct me if I'm wrong) the issue isn't so much clipping the shadows as we see in white balanced histogram in our converter, but, rather, the ADCs of the A900 clipping only the red and blue channel below ISO 320 (which is more obvious when using uniWB,) and this occurs on the hardware level, no matter how much light we get to the sensor. Most people generally clip off their blacks in post, anyways, which makes this phenomena more difficult to see. However, if you have a scene with enough DR where you want to raise the shadows in post, the phenomena may be noticeable, and the real issue to me is not so much the blotchiness, but, rather, the color shifts that the shadows can have. Ultimately, it depends on one's workflow and post-processing methods. For me, since I find the extra bit of noise in ISO 320 barely noticeable, I've been using ISO 320 to be safe. Plus, in the future, better RAW converters may exacerbate the issue, so I figure better safe than sorry. It's kind of like how I deal with UV filters. Most of the time, I don't notice any image degradation from using filters, but if they ruin even one shot, I'd be pretty disappointed, so I don't chance it (unless I'm in harsh conditions.)

  6. #6
    Senior Member edwardkaraa's Avatar
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    Re: A900/A850 clipped blacks

    Yep, as Douglas says, it depends on the workflow. I really do not do much PP work with my photos, apart some basic stuff in the raw converter and dust spotting. I agree though that it may be a problem for someone who does extensive PP. Not for me fortunately
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  7. #7
    hornblade
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    Re: A900/A850 clipped blacks

    Quote Originally Posted by douglasf13 View Post
    the issue isn't so much clipping the shadows as we see in white balanced histogram in our converter, but, rather, the ADCs of the A900 clipping only the red and blue channel below ISO 320 (which is more obvious when using uniWB,)
    Ahh, thanks for this clarification. I have been using UniWB, I'l do some shooting at 200/320 and see if I observe clipped reds and blues. Thanks!

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