To measure something you have to effect it. If 100% of the light passed through a sensor it could measure nothing. If 50% of the light passed through the sensor would only be half as sensitive as an opaque sensor and the viewfinder would only be half as bright as one that uses a mirror.
|Patrick Finds Inner Peace by ecastellon|
from Your best photo of the week!
|Forks by Kukla|
from Arranged everyday objects