Katie sent in an image from Digital SLR Cameras and Photography For Dummies by David D. Busch. The image followed this text (p. 181):

To minimize wrinkles or facial defects, such as scars or bad complexions, use softer, more diffuse lighting, as shown in Figure 10-3.

And here is Figure 10-3 with the accompanying caption (p. 182):

So after learning that diffuse lighting is good for minimizing defects, we are then told that women in general need such lighting. Katie says she tried to imagine the reason for this instruction, but “can’t think of a possibility that isn’t about reinforcing traditionally-gendered imagery.” The assumption in the book seems to be that women always want, and need, to be photographed in ways that emphasize a blemish-free beauty ideal. Not all subjects are “often best pictured” in this way; this instruction is specifically about how to present women. Presumably we might want to picture men in ways that emphasize strength, or show them as wizened or wrinkled or otherwise presented without the softening effect of diffuse lighting.

It’s a small example of how gendered norms are taken for granted and reproduced in various fields. If you’ve seen similar examples (or, for that matter, contrary ones) about photography, painting, etc., we’d love to have them.