Another look at equivalence

Started Jul 22, 2014 | Discussions thread
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Jeff Charles Veteran Member • Posts: 7,514
Another look at equivalence

Sensor size determines equivalence generically, but I was curious about how specific cameras compare to my new RX100m3, so I did some calculations, based on DxOMark sensor tests. DOF differences are pretty much determined by sensor size, but noise performance and IQ can also vary based on technology and megapixels.

DxOMark gives each camera a low-light ISO score, which they define as "the highest ISO setting for a camera that allows it to achieve an SNR of 30dB while keeping a good dynamic range of 9 EVs and a color depth of 18bits."

Using the formula log2(higher ISO/lower ISO) = stops difference, I calculated the number of stops difference for specific cameras compared to the RX100m3. I then used How Many Stops to determine the approximate apertures that those cameras would require to match the RX100m3's f/1.8 at 24mm and its 2.8 at 70mm. Here are my results:

  • Panasonic LX7 - f/1 and f/1.5
  • Olympus OM-D E-M1 - f/2.2 and f/3.5
  • Pentax K5II - f/2.8 and f/4.4
  • Nikon D800 - f/4.3 and f/6.7

Obviously, you can put faster lenses on the Micro Four Thirds, APS-C, and FF camera, but with kit lenses, only the FF camera will do better than the Sony.

Take this for what it's worth, and if you believe that my results are incorrect, or that they don't make sense for some reason, I won't take offense. I had some time on my hands this morning and thought this would be fun to do.

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Leave it in the ground!

 Jeff Charles's gear list:Jeff Charles's gear list
Sony RX100 III Fujifilm X100T Olympus E-M1 Fujifilm X-E2 Olympus M.Zuiko Digital ED 40-150mm 1:4-5.6 R +5 more
Nikon D800 Olympus E-M1 Panasonic Lumix DMC-LX7 Pentax K-5 Sony RX100 III
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