Mornnb wrote in post #17504831
Perhaps 'far inferior' is an exaggeration. But we do have actual comparison data from Dxo, which we can extrapolate on based on the different sensors.
No, we don't have actual comparison data: that would be lenses tested on the same sensor. We have different data that you are using to extrapolate a result.
I am not trying or desiring to defend these Sony lenses, but I do get frustrated when I see these claims that one product is "far inferior" to another. We're going to see the same hyperbole when Sony/Nikon announce their 50 MP cameras. The poor 5DS R will be regarded as "far inferior". And it won't be true.
For a few months I had a D810 with 14-24 and an a7R with the FE 16-35mm. The 14-24mm enjoys a great reputation, but when I tested the two lenses on their native 36 MP sensors I struggled to find much difference in real-world scene tests at 16mm and 24mm, and I did a lot of pixel-peeping. I became comfortable enought with the FE 16-35mm performance to decide to sell the D810 and 14-24 (just preferred the smaller size). It wouldn't be surprising if the FE 16-35mm was not able to hold an equal DXO score to the Canon version if tested on identical sensor because the FE 16-35mm drops off a good deal at 35mm. But, I don't care: it's a 16-28mm lens for me. I have two 35mm primes that I will use before using the 16-35mm. These Mpix scores for zooms are likely averaged over the whole range, so they don't give any sort of detailed picture of the lens' performance.
I own/use two of the top two DXO Mpix scored lenses (Zeiss 1.4/55mm ZE, and 2/135mm ZE), so I know what amazing lens performance looks like, and yet I also enjoy my Sony FE 24-70mm, which, by most reviews, is a turd of a lens. I get nice images from that lens on my a7R somehow. Are the FE zooms "inferior" to the Canon models? Sure, they may well be. But the performance disparity is not extreme.