Can someone explain to me why there is absolutely no visible grain when I look through the viewfinder (which uses a fresnel focusing screen) of my canon EOS 35mm camera ???????????????

If I take off the lens and point the camera at a light, I can detect grain, but not at all when the lens is on.

Aim the camera with the lens on at a light source soft focused. Get a candle at 1ft and focus on infinity and get back to us.