Sigma revealed the Canon 5D Mark IV compatibility warning to all people who are going to buy this Canon product. Actually, issues are easily noticeable when Sigma interchangeable lenses are attached to Canon 5D Mark IV. However, this is not only 5D Mark IV’s problem, but the camera body with almost same features as 5D Mark IV faces the same issue.
Here is what Sigma says:
Canon EOS 5D Mark IV Users
Thank you for purchasing and using our products.
Please find the following notes on the usage of SIGMA interchangeable lenses for EOS, when attached to Canon EOS 5D Mark IV that is released on September 8th.
・ MO (Manual Override) function is unavailable with this camera (Full-time Manual function can be offered).
・ When using a SIGMA interchangeable lens for EOS, setting the corrections to [Disable] is recommended, as “Lens Correction” functions of the camera, such as Peripheral illumination correction, Chromatic aberration correction, Diffraction correction and Distortion correction are not supported.*
* If those functions are activated, the performance of lenses may not be accurate.
* This is not only for EOS 5D Mark IV, but also for other camera bodies with the same function.
We appreciate your continued support for our company and products.