Why this matters
The right way to approach an M3 is to separate optical condition from mechanical condition.
Vintage photography combines a physical object with a technical process. That means the attractive parts of a listing are not always the parts that determine whether you can actually use it. Start by identifying what needs to work for your intended use.
The rangefinder patch is a functional part
Aim the camera at something with a crisp vertical edge at different distances. Misalignment or a dim patch can make the body unpleasant to focus. Also examine frame lines and the finder for haze or separation.
Check bright-line clarity, rangefinder patch contrast, horizontal and vertical alignment and frame spacing. Request a service invoice naming the technician and date. A clean body with an unknown shutter is still a risk.
Questions to send the seller
Can you provide fresh photos of the exact item, including its model and serial number? What functions were tested with film or appropriate media, and what did the result show?
Has a repair technician worked on it? If so, ask for the date, specific work and any supporting invoice. For valuable cameras, ask for a short handling video, not simply a photograph of the shutter button.
A sensible comparison routine
Open a persistent search for the exact model and save three or more genuinely comparable sold results. Separate untested, repaired, recently film-tested and boxed collector-condition examples. Include shipping, import charges and missing parts in your total.
Never treat a currently advertised asking price as proof of market value. When your interest is historical rarity rather than usability, you should also verify the precise variant and its production context.
When to walk away
Walk away from a costly example if the seller will not identify the camera, photograph the actual body or answer basic operational questions. Avoid payment arrangements that bypass marketplace protections.
The right vintage camera is not necessarily the cheapest one. A complete, well-documented example with an ordinary-looking exterior can offer substantially less uncertainty than an unexplained “mint” example.