1:1 isn’t inherently “better” than every other magnification; it’s mainly the conventional threshold for a “true macro” lens. At 1:1, the subject is projected onto the sensor at life size, which lets you capture very fine detail compared with ordinary lenses that may only reach around 1:4 to 1:6.

Why it’s desirable: it gives enough magnification for many classic macro subjects—small insects, textures, and other close-up details—without needing extra accessories. It also means you can make larger prints while preserving more subject detail.

Why not always more? Higher magnification is available, but it comes with trade-offs. Lenses that go beyond 1:1 are more specialized and may be harder to use, with compromises such as slower or manual-only focusing and a narrower range of practical subjects.

Why not less? Less than 1:1 can still be perfectly useful for larger subjects like flowers. Whether you need 1:1, less, or more depends on the size of your subject relative to the sensor and how much detail you want to fill the frame with.