A7s DxOMark

Started 6 months ago | Discussions thread
Happy Jones
Regular MemberPosts: 133
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In reply to TrojMacReady, 6 months ago

TrojMacReady wrote:

Happy Jones wrote:

TrojMacReady wrote:

And arguably, shadow noise is usually the most dominant and limiting factor in low light shots in general.

The SNR graph is just for 18% gray, or middle gray. Not exactly shadows.

If you look at the full SNR graphs below 10% and especially towards 1% gray in the individual reviews or even the DR graph (which reflects shadow noise at high ISO too, since that's the most limiting factor for DR), you'll see the much larger differences.

For example, at a measured ISO 5400 from the A7S, it hits a 10 EV DR, similar to the DR of the A7 and A7R at around ISO 2200-2300. That's well over a stop difference already. Where the A7S touches about 9 stops DR at ISO 21k, the A7 and A7R hit 9 stops around ISO 4700-4900. That's more than 2 stops difference.

Up to a measured ISO 1600, differences in noise will not exceed half a stop, so no, you won't see significant differences there. As expected I would add.

If I have this straight all these cameras will perform near the same for shadow noise at ISO6400 and the A6000 will equal the A7 at ISO12800 because shadows noise is the most important factor to consider at higher ISOs?

Within half a stop for shadow noise based on these graphs, yes. Not accounting for colour shifts and patterns, which these measurements do not represent.

But my comment was mostly within the context of similar formats and a similar technology age (where shot noise is usually pretty close, shadow noise is more about read noise, which tends to differ more between different sensors covering the same format). Here we're also comparing formats with a difference of up to a factor 4 in size, in which case shot noise differences will be much more apparent too.

In midtones the difference between the E-M1 and A6000 can be up to a stop at a measured ISO 6400 according to their measurements, the difference between the E-M1 and A7 over a stop and a half. That should be quite apparent too. Whether crucial or not, will depend on the circumstances, balance of the visible exposure and your expectations.

This was very helpful.

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