35mm being a 3:2 image ratio and 4x5 or 8x10 being a 5:4 image ratio does not direct translate to what is defined as a "normal lens".
Normal lens being defined as size of objects front to rear of the image perceived. Lens choice should be decided on image perspective then focal length needed to achieve this perspective in the print/image.
Typical "normal lens" for 4x5 would be 150mm to 210mm. Typical "normal lens" for 35mm still film would be 40mm to 60mm, but the aspect ratios are different.
Normal lens example, 40mm full frame digital (35mm, 3:2 aspect ratio), aprox diagonal Angle of view 57º. Note size of items in this image.
Wide angle lens example, 14mm full frame digital (35mm, 3:2 aspect ratio), aprox diagonal Angle of View 114°. Note size of items in this image (expansion).
Tele lens example, 300mm full frame digital (35mm, 3:2 aspect ratio), diagonal Angle of View aprox 8°. Note size of items in this image (compression).
Lens focal length should be driven by image perspective/size of objects "front to back" relative to how the "human eye" might see them in real time. Absolute focal length is not as important as lens/camera placement (height, distance to subject and LOTs more) which has a HUGE effect on the image being made.
Bernice
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