To use this White Balance Cap simply attach the cap (you may also hold the lens cap in front on the camera lens) and set custom white balance on your camera the following way

1. Check the manual of your camera about the custom mode for white balance setting
2. Set your camera to this custom mode
3. Install Mennon WB cap in front of the lens
4. Set the focal distance to infinity and zoom to telephoto
5. Aim the lens to the present light source or to the bright sky
6. Press the WB button to measure and save the WB value
7. How you can take pictures with the customized white balance