So you’re new camera has a native ISO/EI of 2000. That’s great when you’re shooting in midday sun. At ƒ22 with a 1/500 shutter speed and you’re still over exposed. Well first you should get back to your shooting stop and preferred shutter speed. If you are shooting at 1/500 for a reason, great. If not, you should be at twice your FPS.
So with motion picture films you can add a Neutral Density filter to cut the quantity of light and not change the color balance of the film. An ND 3 would cut 1 stop, ND 6 would cut 2 stops and so on. Film is not as sensitive to the red and infrared spectrum of light so we could take film to an ND 12 or 18 to reach a desired ƒ-stop without any degradation to the image.
Digital sensors are sensitive to the visible and IR spectrum so if you were to use anything beyond an ND 6 or ND 9 the image recorded will be contaminated with Infra Red. This causes exposures in the blacks to have a more reddish-brown color. Overall, not the desired effect you want in an ND or neutral density filter. Most filter manufacturers make an IR mirror to cut the IR spectrum or combination filters with an IRND in the same filter. To be safe above ND 6, you should consider an IR filter essential.