Sensors in deep

Let’s assume for a moment that you mostly agree with me on the ergonomics of the D70. Quite a few people actually do. Further assume that you mostly agree with me on the functionality of the D70. Again, quite a few people actually do. Sure, we all miss some function, but that is true of all cameras. The D70 fills the spec of the serious amateur surprisingly well. Nikon learned a lot in designing the D1 series and the D100 which they benefit from all the way until today. The learning curve was much steeper back then since digital was relatively new. Not that much happens functional-wise today. Finally, assume that you find the body housing, the grip, the mirror, the prism, etc to be reasonably ok. Sure, the finders of FX cameras are nicer but their weight offset is not.

Now we come to the last factor, the sensor. Here, most of you agree on the sensor of the D70 being outdated. “Everyone knows” that sensors go out of fashion every two to three years. Last generation’s sensor is today’s backyard technology. Some even claim that the best pocket cameras of today can match “old” DSLR sensors like the D70’s. In the film days, models lasted ten years or more. The Nikon F was introduced in 1959, its successor the F2 in 1971, and then again its successor the F3 in 1980. You could use any kind of film (slide or negative, color or b/w, any brand) in any camera body, making updating your equipment a matter of ergonomics and functionality. In the digital era, the sensor is what the film was, but it is fixed. Thus, to the delight of the manufacturers, it seems that you must replace your camera ever so often since sensor progress is so swift. Or is it?

Let’s turn to one of the premier and most well-known sensor labs, DxO, and their sensor (and lens) testing facility DxOMark.  There, you can compare camera sensors in an interactive fashion. Comparisons can be made in two ways that relates to two different aspects of sensor quality, both being important. First, you can compare pixels to see how far the development of individual pixels has come from 2004 until today. Second, you can compare sensor areas, where sensors with higher pixel density will have higher readings since more pixels can contribute to the results. In both comparisons, you compare signal-to-noise ratio, dynamic range, tonal range, and color sensitivity. DxOMark has far more elaborate explanations of these concepts, but essentially, signal-to-noise ratio is how much noise there is in the image, dynamic range is how much lightness and darkness can be accommodated in an image at the same time, tonal range is how many different shades of gray the image can contain, and color sensitivity is the number of reliably distinguishable colors in an image.

Beginning with comparing pixels, the D70 is compared to the newest and most high-tech Nikon at the time of writing, the D800, and the current Leica flagship M9. Looking first at the signal-to-noise ratio, the three sensors are almost indistinguishable. The D800 has a wider range of ISOs, but for any given ISO the results are the same. The D70 performs as well as the two rivals. Noticeable is that the “purist” M9 does a lot of noise smoothing behind the curtain, smoothing that is impossible to turn off. Only having used the M8, I was not aware of that.

Next, looking at dynamic range, the D800 stands out with 2 stops better performance, while the D70 is almost exactly as good as the M9. Which is not that bad since the M9 is considered one of the top cameras which satisfies very high demands.

Continuing with tonal range, it is indistinguishable between the three sensors. Pixels from the three cameras can contain equally many different shades of gray.

Finally, color sensitivity is almost equal, with D70 and D800 being a bit better than the M9. The number of reliably distinguishable colors in pixels from the three sensors is close.

To sum up the pixel comparisons, all cameras perform almost equally except that the D800 has a better dynamic range. The D70 and the M9 are practically equal on all grounds.

Moving on to comparing sensor areas, we compare the D70 to the Leica M8 instead of the M9 since it has about the same sensor size as the D70, and to one of the best pocket cameras, Canon S100, since it is sometimes claimed that today’s pocket cameras have caught up with eight year old DSLRs like the D70. Looking first at signal-to-noise ratio, the M8 is slightly better than the D70 but the S100 is far behind. The difference between the M8 and the D70 is about 1/2 stop while there is a more than 2 stops distance to the S100.

Continuing with dynamic range, the three sensors are fairly equal. The M8 is slightly better at lower ISOs, and the S100 compares surprisingly well to its rivals. Almost equally many levels of light and darkness can be accommodated in images from the three sensors.

Next, looking at tonal range, it is again fairly equal between the D70 and the M8. Images from the two cameras can contain about the same different shades of gray. The S100, though, is almost two stops behind.

Finally, color sensitivity is almost equal between the D70 and the M8. Images from the S100 will suffer a lot from a lesser number of reliably distinguishable colors than the former two.

To sum up the area comparisons, the D70 and the M8 perform almost equally while the S100 pocket camera is far behind. And to sum it all up, the D70 pixels do as well as a new top-of-the line DSLR except in dynamic range, where it lags behind the D800, although it performs equally to the Leica M9. The D70 sensor area does almost as well as the Leica M8 and easily outperforms one of the most highly acclaimed pocket cameras. Through field use of the D70, M8, and S100, I can safely confirm these scientific lab measurements in real shootings. I definitely miss some dynamic range in the D70 compared to, say, a D3x, but other than that, the D70 sensor is doing very well.

The most common reaction I get to all this is disbelief. Can the D70 really measure up to these modern rivals the way it is displayed here? Surely, all the hype about newer and newer sensors cannot be untrue? Surely, the manufactures are not taking us for a ride? Well, the scientific results from DxO tell something else.

As I say in other places too, don’t take my word for it. Listen to others that spend much more time and effort in finding things out. DxO is an organization I find credible and objective. But they are cautious, too. They have a popularized simple overall score that is derived only from some extreme values of their measurements. This overall score greatly amplifies small differences to make it more “interesting” and in line with expectations. The way the score is calculated is not published, so we cannot know exactly how it works in detail, but it’s obvious that is works more like the common perception of sensor development. Thus, the Nikon D800 and D800E receive the highest scores ever, 95 and 96 respectively. The Leica M9 receives 69 and the Nikon D3100 67. The D70 obtains a score of 50 which is exactly what the Canon S100 also does. But it is evident from the graphs above and from shooting them that the S100 is clearly inferior to the D70 in terms of image quality. Thus, the DxOmark measurements are very interesting but their popularized overall scores are not. Rather, they are misleading.

But again, although DxOMark is a fascinating site, I wish for you to spend more time creating great images than comparing camera sensors. My main point here is merely that you need not worry about your equipment aging, just go out and have some fun. Nobody will ever be able to tell whether you used a D70 or something newer (unless they peek into your EXIF data).

All graphics come from the DxOMark website, thus their copyright.

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