maxotics Posted July 9, 2014 Share Posted July 9, 2014 The tests done with the a7S seem pretty indisputable to me, that in FACT, the camera has the best high-ISO performance of any camera. Whether you need it in real-world situations is subjective question. The question most others are interested in is the tradeoff the camera makes between low noise at high ISO and less DR at base ISO. All sensors have a base ISO at which they perform optimally. Everything after that is degraded. Apparently, and I don't fully understand this myself, higher sensel count cameras improve DR at base ISO. In other words, the a7S will be better at low-light than the a7, but the a7 will have better DR at base ISO (say 100). It is not the low megapixel count that makes the a7S more sensitive to light, it is the LARGER sensel/pixel size on the sensor. Each sensel is like a little telescope/radio dish with a colored filter in front of it. As in astronomy, you can collect radiation through lots of little dishes, or one big dish. In picking up faint objects, the bigger the better. In short, larger pixel, less noise, period. There is nothing temporary in this area of physics. I do not see TV stations replacing their satellite dishes with 50 little dishes. Again, it is NOT about the low megapixel count. It is about the increased pixel size (more sensitivity/less noise) of the a7S that makes it unique. Here is someone's calculation of pixel width Approximate pixel pitch (in microns) Refer to the reservations here about calculating the "true" width and area of an individual pixel. Pixel pitch in microns = width of sensor in millimetres divided by image width in pixels multiplied by 1000 A77 = 3.917 (23.5 / 6000 x 1000) A7S = 8.443 (35.8 / 4240 x 1000) Relationship: A7S is approximately 116% greater than A77 http://www.robsphotography.co.nz/Sony-A77-SonyA7S.html Would you rather have a 4 inch telescope or 8 inch telescope when peering into the night sky? Quote Link to comment Share on other sites More sharing options...
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