It doesn't surprise consumers and professionals that the problems arising from incompatibility between Canon and Nikon DSLRs with third party lenses is growing. Canon and Sigma, in particular, haven't been going along smoothly; and with the 5D Mark IV, the future isn't looking too bright.

The most recent issue revolves primarily on Sigma's lenses when users try to use it with Canon's 5D Mark IV. These lenses are incompatible with the camera's manual focus override when users want to refocus while the AF is enabled.

There's no official statement yet regarding the fix and when users can expect it to roll out. For those who have the 5D Mark IV and a Sigma lens, chances are users need to only use manual focus, otherwise issues will tend to take place.

Aside from this issue, there's another one concerning those using the Canon lens correction function with a Sigma glass. This has been going on for a while, but no fix has been made up until today. The only fix advised by Sigma is to turn off the lens correction feature altogether.

Here's a portion of Sigma's memo for Canon 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.

Hopefully, Sigma will be able to provide the fixes soon in order for Canon 5D Mark IV owners to take full advantage of the quality that both products offer at the same time.