[Brightcolours]

The testing was done on a Canon camera with a Canon sensor which means it is not translatable to other camera ecosystems. Yes you can take it as a guide but no more.

That is of course not true at all. If a lens performs well on one camera, it will perform well on another.

If you meant this in respect to the OTUS, it still is not true. Lenstip in this very review points out that the MTF results on their Canon bodies (1D mk III, now 5D mk III) are about 1 lp/mm lower than the results with the D3X they test with.

 

Another question is as Sigma always releases its lenses for Canon first have they done any fine tuning to get the best on existing Canon sensors or not ?

There is no fine tuning for a sensor. That statement just makes no sense... 

A sterner test would be to compare performance on something like the Nikon D800E. Does the Sigma resolve 22 MP or 28 MP or even 36 MP ?

 

Personally I judge a lens by micro contrast once a lens reaches a decent level of performance, but the numbers are important to some.