The TS-E 24L II holds up remarkably well under 50MP.
The following link compare the TS-E 24L and the legendary 300/2.8L II, both lenses attached via 1.4xTC. The 300 is noticeably sharper in the centre of frame but the 24L shows it's strength in the corners of the 1.4xTC image (equivalent to mid-frame of full frame image)
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=486&Camera=979&Sample=0&FLI=1&API=2&LensComp=739&CameraComp=979&SampleComp=0&FLIComp=1&APIComp=3
The above comparison simulates resolving power under 2.9um pixels at least for the central portion of the frame. This equate to about 38MP on APS-C. These new generation Canon L lenses really pack quite an optical punch.
The following link compare the TS-E 24L and the legendary 300/2.8L II, both lenses attached via 1.4xTC. The 300 is noticeably sharper in the centre of frame but the 24L shows it's strength in the corners of the 1.4xTC image (equivalent to mid-frame of full frame image)
http://www.the-digital-picture.com/Reviews/ISO-12233-Sample-Crops.aspx?Lens=486&Camera=979&Sample=0&FLI=1&API=2&LensComp=739&CameraComp=979&SampleComp=0&FLIComp=1&APIComp=3
The above comparison simulates resolving power under 2.9um pixels at least for the central portion of the frame. This equate to about 38MP on APS-C. These new generation Canon L lenses really pack quite an optical punch.