Patent inquiry of sigma lens

I struggled with this problem for half a year and finally found a solution on foreign websites. Foreign netizens provided various methods, so I tried to translate them.

1. Most of Sigma's lenses have problems with Canon's digital SLR, because Sigma didn't buy Canon's patents. The solution: put your lens on a full-size Canon camera, adjust the F value to the minimum, and take a photo. Then, it can be used on your original camera.

2. Turn to Av mode, set the f value to the maximum value (F22), and then take photos. That's good.

3. Turn off and turn on your camera, do nothing, switch directly to Av mode, switch to the maximum aperture (minimum F value) to focus manually and take pictures. Then you can work in any mode.

If you can understand English, please search for solutions in English.