Photo collection...of who?

Some porn starlets probably. And her reaction is kind of sweet I think.

The link to Ran-Sama takes you to Yukari.

Here's my two cents on the commentary translation:
All dirty books in this pool are centered around a certain theme, except this one. Since the original text is basically "Photography stuff", my guess is "Photography themed" might be a clearer translation.
I assume when Aya said "only one shot", that meant one shot of herself having sex or nude, etc. So I'm thinking stuffs like post 1438554, post 454809 (contains loli), and post 1004458 (Camera not present in image). Basically people doing dirty stuff while being filmed/photographed.

A beauty like you deserve 100 photos from it.