DxO Publishes OM-D Sensor Test Results

Discussion in 'Mirrorless Digital Cameras' started by bruce_rubenstein, Sep 24, 2012.

  1. The results are here: http://www.dxomark.com/index.php/Publications/DxOMark-Reviews/Olympus-OM-D-E-M5-The-best-of-the-micro-4-3-cameras
    The new Olympus OM-D E-M5 sensor is an important contribution that brings micro 4:3 cameras roaring back into the game. During Photokina 2012, Olympus unveiled two new cameras in the Pen line, the Pen E-PL5 and Pen E-PM2, both of which are equipped with the same sensor as the OM-D E-M5. These Olympus high-end compact hybrids achieve scores that approximate those of their APS-C rivals (such as the Sony NEX). Simply put, the OM-D E-M5 is equipped with the best sensor we have ever analyzed for a micro 4:3, and to date the closest to that of the Sony NEX.​

    I suggest looking at the the graphs of the test data. Relative to other cameras the ISO has a significant effect on performance.
     
  2. These results make me feel pretty good about my GX1. It performs *close* to cameras well out of it's class range, and especially in terms of low-light shooting better than many. The X-10 especially seems outclassed, but I guess it has a much smaller sensor than the rest?
     
  3. Frankly, I have lost all interest in what DxO say. Their test results bear little relevance to real life photography. Any website that can rate the sensor of a Nikon D5100 and Sony A580 better than those of the Canon 5D MkII, Canon 1D MkIV, Phase One P45 and Leica M9 is worth ignoring.
     
  4. I have a GX1 and (until very recently) a Nikon D300. Their DxO high ISO ratings are roughly equivalent and I could see that clearly in the images I took with the cameras (if anything, the GX1 is slightly better, and this for a 16mp m4/3 camera vs a 12mp APS-C). However, the GX1 cannot touch the real-world dynamic range performance of the D300, and this seems to be consistent with their respective DxO ratings (1.4EV difference, however that maps into performance in actual images). In other words, I have a very limited sample set but the DxO results do not look wrong to me, at least for these two cameras
     
  5. > Relative to other cameras the ISO has a significant effect on performance.

    Exactly, Bruce. DXo shows that ISO 200 is actually equal to ISO 100, underexposed one stop, and overdeveloped one stop. This improves highlight retention at the expense of shadow noise. Total dynamic range is the same, just better distributed.

    To me it seems like an excellent solution. It is fundamentally the same as Canon i-Contrast, Fuji software DR, or Samsung DRO. It's probably why I prefer OM-D results to any APS-C camera.
     
  6. I don't think that either one of you has any real grasp of what an ISO rating means. The ISO standard ISO 12232:2006[54] gives digital still camera manufacturers a choice of five different techniques for determining the exposure index rating at each sensitivity setting provided by a particular camera model. http://en.wikipedia.org/wiki/Film_speed
    If one were to actually look at, and comprehend, the data in the graphs it would be obvious that the data is plotted for measured ISO. Nothing is under exposed.
    It is fundamentally the same as Canon i-Contrast, Fuji software DR, or Samsung DRO.​
    That's JPG processing. DxO data is for sensor performance from RAW files.
     
  7. Bruce, I have no idea where you are going with paragraph one. How does this DxO chart disagree with what I said, or with ISO 12232?
    00arSy-497701584.jpg
     
  8. What effect does that have on the image?
     
  9. Bill, strictly speaking, for a graph that is linear in log space, your statement that ISO 200 is the same as ISO 100, underexposed and overdeveloped, will always be true, whatever the camera. I think what Bruce is saying is that the test results show that the picture has actually to be exposed to twice the amount of light than expected to get a correct exposure according to the ISO standard. The slightly pedantic difference with your implied statement is that the picture is not actually underexposed in the test.
     
  10. From the Online Photographer, DxO Gives OM-D High Marks, comments:
    Dear Marcin,
    No, that's due to a fundamental misunderstanding of ISO by their readers. Industry-standard camera ISO and sensor ISO are determined in entirely different ways and mean different things. I've posted a lengthy comment to the thread there explaining this. Likely I will turn that into a column here, delaying my “RAW isn't raw” column, but it's an important lead-in to it.

    pax \ Ctein
    http://theonlinephotographer.typepad.com/the_online_photographer/2012/09/dxo-gives-om-d-high-marks.html#comments
     
  11. You can make this as complicated as you want, discussing photons if you like, but the stunning (for m43) dynamic range, or exposure range as Ctein likes to call it, of the OM-D E-M5 is helped by it being more underrated for ISO than any other digital camera. If you can disprove that by posting a DxO chart, please do! Some cameras, such as the Fuji X10, are overrated for ISO.
    00areg-497793984.jpg
     
  12. Why ISO Isn't ISO

    By Ctein
    Photographers have the idea that ISO (whether analog or digital) is a fundamental physical measurement, a way of describing the "photon capture efficiency" of a film or sensor. It's not. Ultimately, what it's really about is what exposure will produce the best-looking photograph for a particular subject luminance, according to the collective judgment of viewers. That is a pretty wobbly criterion.
    ...

    The bottom line
    That's why DxOMark gives you a plot of camera ISO vs. sensor ISO. It doesn't reveal that a camera manufacturer is "fudging" or "lying." It tells you how the two different kinds of ISO, which are legitimately determined in very different ways, compare. That's all. It's not an exposé. It's just technical information. So far as real photography practices go, we care a lot more about camera ISO.

    The rest can be read here: http://theonlinephotographer.typepad.com/the_online_photographer/2012/09/why-iso-isnt-iso.html
    Ctein has been an authority on this sort of thing for decades. Bill Tuthill is just another confused hobbyist.
     
  13. Frankly, I have lost all interest in what DxO say.​
    That is because what they say does not make sense to you. But if you put the effort to understand what they are measuring, you'll find it worth your time. Ignore the aggregated score and how cameras are ranked on that and look at the individual graphs and scores to get a better understanding of where cameras differ in performance. Also keep in mind that sensor scores are unrelated to sharpness or DOF capabilities which people praise in cameras with large sensors (as the M9). The M9 scores low because it is noisy - its noise performance is at the level of first gen FF cameras and that level is now attained by MFT and APS-C sensors. Some medium format cameras score low because they don't have high ISO settings at all. Other cameras score low in some areas because they don't have low ISO settings available. If you don't look at the details, the scores will seem arbitrary, but they all reflect a certain aspect of the camera performance - all, except the aggregated score which is a hodge-podge of everything and doesn't really help you figure out anything by itself.

    Misunderstanding about dxomark pops everywhere. As an example, when dxomark rated the D800 over the 5DIII, all Canon users were in disbelief. They misunderstood the reasons so much that they were posting high ISO images from both cameras to show that Canon images looked better at 100%. But dxomark shows that the D800 is better than the 5DIII *at low ISO*, because it offers much more DR. That detail was unfortunately lost on many people who claimed in turn that dxomark is nonsense and that they have "clear proof" of that in their high ISO samples.
     
  14. You can make this as complicated as you want, discussing photons if you like, but the stunning (for m43) dynamic range, or exposure range as Ctein likes to call it, of the OM-D E-M5 is helped by it being more underrated for ISO than any other digital camera.​
    You are missing the fact that when dxomark plots DR, it does it in terms of it measured ISO, not in terms of manufacturer ISO. Any graph comparisons you make with other cameras is made in terms of measured ISO. So how each manufacturer calculates ISO is made irrelevant for performance comparisons.
    Just hover your mouse over the graphs and you'll see they are based on the measured ISO. The low light score of the E-M5 - 826 corresponds to a bit past the camera's ISO 1600 setting. It basically tells you that you can set your camera to ISO 1600 and you'll still get IQ past the dxomark IQ bar.
    There is nothing special here about the E-M5. The D800 also has its measured ISOs lower than the marked ones throughout most of the range.
     
  15. This thread on DPreview discusses the issue, for anybody who cares. I don't.

    http://forums.dpreview.com/forums/read.asp?forum=1041&message=42600801

    D800 graph on DxOmark does not compare. Half stop under nominal at most, over at ISO 50.
     
  16. D800 graph on DxOmark does not compare. Half stop under nominal at most, over at ISO 50.​
    This is like that joke where we agreed on the principle, but we're haggling about the details.
    As the article you provided a link to says (thanks for the link):
    That's why DxOMark gives you a plot of camera ISO vs. sensor ISO. It doesn't reveal that a camera manufacturer is "fudging" or "lying." It tells you how the two different kinds of ISO, which are legitimately determined in very different ways, compare. That's all.​
     

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