M39 can refer to more than one historical specification. An adapter advertised only as M39 may not establish the intended register distance.
Make the exact-model decision
Verify the exact camera and lens standard in their manuals, including thread pitch and register. First identify the physical mount on the camera and lens, not just the maker name. A body may support a separate older family only through a named adapter.
A manufacturer example
Fujifilm’s M Mount Adapter page describes M-to-X direction, a compatibility gauge and camera settings such as Shoot Without Lens. Use the linked page for its stated model and revision; a different model may need a different support document.
Where to draw the line
A match in the mount label establishes a route to investigate; it does not prove image coverage, AF mode or rear clearance. If a source does not address the exact feature you need, record that feature as unknown rather than treating silence as support or incompatibility.
Your next step
Take the model code from the body or lens label, open the official source below, and compare its scope with the equipment you have. Then use the compare mount systems to organize what is known. Do not mount an item that resists or appears on a maker’s exclusion list.
Official sources and scope
Checked for this reference on October 30, 2026. Product firmware and support lists can change; inspect the current maker page for your exact revision.