Because the X-Pro1’s optical finder is not through-the-lens, the bright frame can only ever be an approximation. Parallax changes framing with subject distance, and it also changes with your exact eye position in the finder—especially if you wear glasses. Lens focal length is only approximate, and effective focal length can shift with focusing distance, so a single fixed frame cannot perfectly match every situation.

Fuji therefore makes the bright frame conservative: it shows what will definitely be included rather than risking cutting off parts of the scene. Cropping extra area later is safer than missing something important at capture.

There are also optical-viewfinder distortions and lens-dependent variations that make exact framing harder than simply drawing a more precise rectangle. This is normal rangefinder-style behavior; even expensive cameras with similar finder concepts behave this way. For close distances and macro, the mismatch becomes large enough that cameras often switch users to the EVF instead.

Later Fuji models improved this by shifting frame lines based on focus distance, but on the X-Pro1 the OVF bright lines are best treated as approximate composition guides, not exact framing boundaries.