Fouad,


We use both the 70-200L 2.8 IS and the 24-70L 2.8 among others on 1DMK11 bodies.


The reason we use the 24-70 is that we have the focal length 17-55 covered on an XTi body.


For the work we do; mostly nature/building related, the 17-55 as a walkaround lens is nice on the 1.6 crop body. That being said, as this lens will not fit a 1D body we needed a similer lens for those 1D bodies to cover that range.


We also use a 24 T-S and 10-20 Sigma. We find that this covers that range very well for us.


Over the many years we have found there is no free lunch and compromises must be made. You might also read this on other reviews and comments.


I hope this helps somewhat..


regards... Chris...