Equipment & Techniques > Cameras, Lenses and Shooting gear

Are B&W Photos Affected by APO Lenses?

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Michael Erlewine:
I know that APO (apochromatic lenses) are designed for color and that non-APO lenses can have all kinds of ugly fringing, etc. My question is, do non-APO lenses affect B&W photography. Does the fringing only occur in color or is there anything from axial and lateral chromatic aberration that shows up in B&W photos? Probably a stupid question, but a question nevertheless.

shadowblade:
Black-and-white photos are affected because the image is captured in colour first, before tonemapping curves are applied to produce a black-and-white image. These curves are generally not the same for every colour; therefore, there will be a fringing effect in the final black-and-white image.

Michael Erlewine:
Thanks! That is what I assumed, but I have had little (recent) experience with B&W photography.

uaiomex:
I would say that even a native (no bayer, no filters) b&w digital sensor or b&w film improve with apo glass. The color offset "ghosts" produced by non apo chromatic aberrations decrease apparent sharpness and create linear artifacts. Me thinks.
Please experts chime in.
Eduardo

Bart_van_der_Wolf:

--- Quote from: uaiomex on March 30, 2015, 03:59:22 am ---I would say that even a native (no bayer, no filters) b&w digital sensor or b&w film improve with apo glass.
--- End quote ---

Yes, and it's due to the better focus of all wavelengths for which the same plane of focus is achieved, at the same time.

Since we humans respond mostly to luminance resolution (and luminance can simplified be seen as a weighted combination of e.g. R, G and B wavelength bands) that synchronized focus of more wavelength bands is helpful. It will also not hurt our very high visual acuity for colors (due to the dense packing of cones in the Fovea Centralis), but the chrominance can still be harder to separate visually than luminance, and our eyes with their single imperfect lens may not be as well APO corrected ...

Cheers,
Bart

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