I've always wondered about the Sports ISO specified in the Camera Sensor DXO Marks - what that meant. So today i looked it up on their site. And it seems to be remarkably useful.
http://www.dxomark.com/About/Sensor-scores/Use-Case-Scores Quote: An SNR value of 30dB means excellent image quality. Thus low-light ISO is 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.
So when comparing cameras across mfr lines and across sensor sizes, one can now use this Sports number to qualitatively compare low light performance.
I object slightly to labeling it a "sports" rating, however. Anyone shooting moody pictures in the evening or indoors, knows the need for better low light performance.
Here's the kind of low light picture i'm talking about - taken during an evening art walk in a small town. Goal was to capture the mood and feeling of crowds walking around on a winter's evening - sampling and gossiping about this months art displays. Taken on a handheld Nex 6 with a Pentax 50mm f1.7 manual lens. 1/160s, probably fully open, iso 800. It was a struggle to keep the noise level down when processing this RAW image. A lightweight monopod or tripod would have been useful. But one can also see the camera i was using, the Nex 6, altho very portable, does not have the highest sports rating out there. But is it usable - of course.
[IMG]
[/IMG]
Here's a listing of "sports ISO" for some typical cameras:
1" sensor
Nikon 1 V3
384
Sony RX100 Mk3 495
Micro 4/3
Panasonic GH4 791
Panasonic GX7 718
APS sensors
Nex 6:
1018
Pentax K5 1162
Pentax K3: 1216
Nikon 7100 1256
FF sensors
Sony FF A7 2248
Sony FF A7R 2746
Sony FF A7S
3702
Nikon FF 610 2925
Nikon FF 750 2956
Nikon FF 810 2853
Nikon FF 4S 3074
Now, instead of just comparing MP numbers, we can also compare a number that means a lot more to me: ISO capability.
I have friends that talk about how wonderful their RX100's are, but yet look at their ISO performance: 495. And the folks that talk about how wonderful their 1" sensors, like the Nikon 1: 384 - not that great for low light.
From reading camera ads, one would think that all these cameras are stellar in all ways. Look at the details and differences emerge. And the MP density don't help certain cameras. For example, the D810 with its 36mp actually rates worse on its ISO than the more humble D610 with 24mp.
I keep reading comments that it will be 5 to 10 years before mirrorless cameras compete with DSLRs. Well according to the above data, the top dog in FF low light performance is the unusual A7S, and frankly is the camera i'm currently lusting after
If i'm missing something here, let me know. But i think this ISO capability is an interesting yearstick for the cameras i'm interested in.
Last edited by philbaum; 12-08-2014 at 11:33 AM.