Quote Originally Posted by hrst View Post
"Ortho" film usually means it IS spectrally sensitized (with sensitizing dye) for green wavelengths, in addition to blue. Non-sensitized emulsion is blue-sensitive only. Those are also available for some special purposes such as copy films as mentioned before in this thread.
That should be why the swedish flag looks like the finnish one on really old photos, taken with blue-sensitive plates (blue went light and yellow dark), but look swedish with modern ortho film. Green has some yellow in it.