The Economist article on mirrorless cameras

Started Jun 7, 2014 | Discussions thread
philip pj Senior Member • Posts: 1,608
Re: Which laws of physics?

It's a photography forum, not a physics forum - so it is a good idea to confine the conversation to the data we have at hand - the highly respected DxO data sets. It can happen that certain people have issues with these data, and I suggest they take them up with the custodians - DxO or whomever.

Now, we have a discussion related to the a7r and canon FF cameras - here I refer to the 5DIII.

The DxO data are unequivocal and imbued with clarity - and present few difficulties in analysis. They are as follows:

'Signal' is virtually identical for the two cams throughout the ISO range users will use;

Dynamic Range is virtually identical for both from a true ISO 1600 up to the claimed ISO 25600; the real difference is that the Canon improves its DR measure virtually not at all from ISO 800 to ISO 100 (both claimed), whereas the a7r keeps improving for these very important landscape and high IQ ISO levels near base ISO, right up to a max of 14.07 stops at ISO 100. The Canon figure at ISO 100 is 11.74 stops, a full 2.33 stops.

The result for this very poor result by Canon is a much greater risk of clipped shadows and/or clipped highlights for images for which FF cameras are used for - maximum quality!

The a7r also does substantially better regarding color depth at ISO levels below ISO 3200.

That's the measure of superiority. Except there is more:

. the Sony a7r has very fine grained aesthetic noise, similar to film grain - much nicer than the Canon's blotchy noise;

. the a7r is 36Mp which feeds directly into higher IQ, better resolution via sensor MTF (22% higher).

Putting it together:

. better DR where it counts, and equal DR at high ISO levels;
. better colour (backed up users' subjective feedback);
. better noise character (subjective but likely to be obvious);
. higher resolution and better image quality.

I cannot see any characteristic the Canon is the better choice.

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