Important hood depth

It goes without writing that any unnecessary light source should be eliminated when we press the shutter intending good transparencies or good digital images. In movie field, "Barn Door" is set on the movie lens frontal end to cut off harmful light source intending "Halation cut-off" method. The requirement for good pictures is the same as still camera field. So, any adequate measure for outer strong light source that has nothing to do with the object is indispensable especially in a severe location.  And most of the case genuine hoods coming with lens purchase lacks depth at all.
According this principle, old and ancient lenses while there was not any lens surface coating technology are available even on recent digital formatting. Thanks to a convenient adjustment soft-wear Photoshop, "Tone curve", color tone balance is adjustable anyway we want.