I suspect a 35 f/1.4 L II will be in the same ballpark as the new 24-70 f/2.8 L II at the very least, which would put its IQ just a little better than the Sigma 35 f/1.4 (which, while it is an excellent lens, still doesn't have the center and mid-frame performance of even the 24-70/2.8 L II...which is a ZOOM!)
now, now... no need to tell lies. the 24-70 mk2 is good.. but not THAT good.
No lies involved.
Regarding the test cases you linked...I see no mention of any kind of calibration to maximize the performance of each lens with the camera body they were tested on. As a matter of fact, the FAQ on that site quite explicitly states they only test with one copy of any given thing, and still makes no mention of optimizing each lens for the camera body that is used in testing. One has to wonder if the samples used were producing the best results...in both cases (Sigma's 35mm and Canon's 24-70mm). Second, the post of mine you quoted was comparing the Sigma 24-70 with the Canon 24-70. Your two links are, effectively, comparing the Sigma 35mm to the Canon 24-70...something I never attempted to do. My final statement is a prediction and projection, not a direct comparison of any 35mm lens to any 24-70mm lens. According to the MTF charts, the Canon 24-70 is quite a bit better, from a resolution standpoint, center to corner, than the Sigma 24-70. I am PREDICTING that, IF Canon releases a 35mm f/1.4 II, there is no reason to suspect it will not perform on a similar level...which would make it's performance slightly better than the Sigma 35mm (not necessarily by as much of a margin as with the 24-70...but enough over the old Canon 35mm f/1.4 to make the upgrade, and the price, worth while.)
Regarding the tests you linked...you are making the same mistake many people do, in thinking that a test, like those you linked, is truly indicative of THE LENS. Most review sites test "camera systems", not lenses or cameras. Combining a lens with a camera is going to produce a result that is a convolution of all the components in combination. Those particular tests both use a 1Ds Mark III...which, while it has a high megapixel count
, is not particularly high in pixel density
. The sensor is going to be the limiting factor there...diminishing returns have already set in. To truly compare the resolving power of a lens when tested as part of a camera system, you need to throw the highest density (highest spatial resolution) sensor you can find at it. One of Nikon's 24mp APS-C cameras would probably do the job well enough. I would bet money that the 24-70/2.8 II would start show it's strength there.
The only true way to get an idea of the real
resolving power and sharpness of a lens is to reference a mathematically generated MTF chart from the mathematical models of the lens design itself, which factors in the optical materials, their refractive and dispersion indexes, etc. You can never produce an MTF from an image produced by a lens attached to a camera that truly represents the capability of the lens itself...you are only producing an MTF of that particular camera system...that lens and that camera specifically. You could compare your own MTFs of say a Sigma 24-70 and a Canon 24-70, so long as you produce those MTFs with the exact same
camera, in the exact same
lighting conditions, with exact precision
in terms of sensor plan distance and angle from the test chart, so long as each lens is ideally calibrated for that camera
. To improve the accuracy of such a test, several copies of each lens should be used with several copies of a camera body, and better yet, with a couple sets of camera bodies of differing pixel densities (say an 18mp FF and a 24mp APS-C), and each setup should be run through a test sequence multiple times, with statistical outliers discarded from final average results and standard deviations. Only then could one say a comparison of any one lens to any other lens is truly objective
Such subjective tests are useful in a general sense, and are useful for a casual comparison of someone browsing the web for information on what lenses to consider buying. Personally, if I just want to compare two lenses, I opt to compare the manufacturer's mathematically generated MTF charts that demonstrate JUST the performance of the lens, and nothing else. I am not trying to "lie"...just trying to be as objective as I can. I'm not in it here to make a purchase...if I was, I'd factor in a whole lot more sources, providing a variety of viewpoints with a variety of test methodologies ("real world" tests, scientific/objective tests, etc.), including testing out the lenses myself, before actually making a decision.