In some camera forums (especially DPReview), it is commonly said that dynamic range is the Achilles' heel of Micro 4/3 sensor technology. While the sensors in our Micro 4/3 cameras are competitive in resolution, and to an extent high ISO signal relative to noise, they are said to lag behind APS-C competitors when it comes to dynamic range. The first thing to clarify is that not all APS-C sensors are alike. According to DxOMark, the GH2 (4/3) sensor has 11.3 stops of DR at base ISO while the Canon 60D (APS-C) sensor has 11.5 stops, and the Pentax K5 (APS-C) sensor has 14.1 stops. If dynamic range is a relative defiiciency for Micro 4/3, it is only the case relative to specific, recent APS-C models. What is dynamic range and why does it matter? DxOmark defines sensor dynamic range as follows (source): In simple, practical terms, a camera sensor with high dynamic range (DR) is able to simultaneously capture detail within two areas of the frame which vary greatly in brightness from one another. All of us have encountered the limits of our camera's DR at one time or another, typically when attempting to expose for a subject in shadow without "blowing" the highlights. Nowhere is this limitation more evident than with small sensor compacts, especially camera phones. Here's an example where I tried to expose for my son's face and ended up clipping highlights throughout the image: One critical thing to keep in mind when considering DR is that it is always possible to preserve highlights if one is willing to accept "blocked up" shadows. For example, in the image above, I could have used a much faster shutter speed to preserve the highlight information. People often comment that "X camera blows the highlights"; however in reality, people blow highlights, while cameras simply follow orders. The issue in a shot such as the one above is that preserving highlight information would have meant leaving the subject deep in shadow, and to get him to the desired level of brightness during processing, I would have had to substantially "push" the shadows leading to increased noise and decreased color fidelity in those regions compared to what I ended up with above. The difference between a high DR sensor and a low DR sensor is that the files from the former can be "pushed" hard during processing while maintaining clean tones in the recovered shadows (due to low sensor read noise). Do Micro 4/3 camera sensors really have less DR than class-leading APS-C sensors? Yes, they do. The more important question is "Does that matter, and if so how much?" I think that most of the chatter which goes on regarding Micro 4/3 and DR is ill-informed, based more on charts and measurement than on real world results. One simple reason for this is that charts are all most people have to go on. None of the major review sites provide real comparative examples of DR. At best, we get scientific data from properly performed testing (DxOMark), while more commonly we get scientific data from less well conducted testing. So why don't we get real, comparative examples? I'm not sure, but I think at least part of the reason is that such comparisons are difficult to do and present in a controlled manner. I will attempt to present one for you here, and you will see that despite my best efforts (given limited time and resources), there are some methodological flaws. The cameras I am testing here are the Panasonic GH2 (my primary camera for personal use) and the Pentax K-5, an APS-C camera which features a Sony sensor which set the new standard for DR performance amongst APS-C sensors. Here is my test scene, which contains a DR that exceeds the capture ability of either camera sensor: Test details: There was not a cloud in the sky and both images were taken within minutes of one another, so lighting conditions were fixed (critical for meaningful DR testing). Each camera was used at its respective base ISO. I attempted to match framing, but the K5 ended up slightly tighter (a minor advantage for the Pentax in terms of effects on outcome). I also stopped down the K5 lens 2/3 stop relative to the Panasonic, but the latter still had more DOF (a minor advantage for the Panasonic, although the crops presented are within the DOF for both). With each camera, I experimentally determined a shutter speed such that the RAW highlight data would be slightly clipped (unrecoverable). Thus controlling for highlight latitude, the degree of shadow latitude would determine the difference in DR performance between the two cameras. Below, you can see a crop from a highlight region. Rollover (mouseover) the crop to see what happens after a negative 4-stop exposure adjustment in Lightroom (GH2 on left, K5 on right): https://farm6.static.flickr.com/5063/5675405599_178f0984ca_o.png" rsrc="https://farm6.static.flickr.com/5108/5675405783_1510608327_o.png" border="0"> As you can see, the highlights are slightly more recoverable in this particular GH2 file. Again, it is important to understand that this difference is a function of the exposure parameters (shutter speed and aperture) chosen by me and not a function of sensor differences! The presence of absence of blown highlights, considered in isolation, tells you nothing about sensor DR. However, understanding that the chosen exposures have nearly* matched highlight range, we can now look at the shadow performance. *By allowing the Pentax to clip slightly more in the highlights, I have given it a small advantage in the shadow region. DR testing ain't easy! In the shadow crop comparison below, the GH2 is on the left, and the K5 on the right. Rollover the image to see shadow recovery after a positive 4-stop exposure adjustment in Lightroom: https://farm6.static.flickr.com/5069/5675966734_5401229e77_o.png" rsrc="https://farm6.static.flickr.com/5222/5676221094_f9be439747_o.png" border="0"> You can see that the pushed K5 shadows are cleaner. As a result, the foliage structure is more apparent. I highlighted two small regions with yellow boxes where you can make out the leaf patterns with the K5 which are less distinct with the GH2. Keep in mind that these are 100% crops from 16MP files! At 50%, which still corresponds to a large print, the differences become quite small: [IMG]https://farm6.static.flickr.com/5222/5676221094_6c17cfe0da.jpg Here is another shadow region 100% crop. Once again, the GH2 is on the left, the K5 on the right. Rollover the image to see shadow recovery after a positive 4-stop exposure adjustment in Lightroom: https://farm6.static.flickr.com/5184/5675405437_acd49e6044_o.png" rsrc="https://farm6.static.flickr.com/5230/5675967000_d912d1d720_o.png" border="0"> Once again, more of the shadow detail is recoverable in the K5 file (look at the bark). However, differences are again modest at 50%: [IMG]https://farm6.static.flickr.com/5230/5675967000_88369868ab.jpg Below is the resized entire GH2 frame after "Auto tone" in Lightroom. Rollover the image to see the corresponding K5 frame. https://farm6.static.flickr.com/5262/5675966552_472b1487f6_o.jpg" rsrc="https://farm6.static.flickr.com/5029/5675404909_9f7a2d7f86_o.jpg" border="0"> Conclusions: [LIST] [*][B]The K5 has demonstrably more DR, but the difference is subtle even at 50% pixel view on screen.[/B] In my experience, 50% view on screen tells me all I need to know about how large prints will look. 100% view is not all that relevant. [*][B]The difference in DR is apparent only after substantial pushing of the shadows.[/B] This kind of shadow pushing is not a common event in my postprocessing. With a shot such as the example shown in this article, I tend to leave the shadows dark, similar to the displayed shadow crops [B]prior [/B]to rollover. In that case, the difference in DR is simply not apparent. [/LIST] In summary, the widely discussed disparity between Micro 4/3 DR and APS-C DR (represented here by the best of the APS-C breed) is of limited field relevance. If DR is the Achilles' heel of Micro 4/3, I'd say we're in pretty good shape.