A rangefinder is a simple machine, and that is exactly why a used one needs a careful look. There is no autofocus to hide a misaligned patch, no screen to tell you the shutter is dragging, and a lot of the bodies you'll meet are decades old. I check every M that comes across my counter the same way, and it takes about ten minutes. Here is that routine, so you can run it yourself before money changes hands.
The short answer
Do this…
- Check the rangefinder patch at infinity and at close focus, on a vertical and a horizontal edge
- Fire every shutter speed and listen for the slow ones
- Look through the finder at a bright sky for haze, fog and separation
- Bring a lens, a small flashlight and a charged phone
Don't do this…
- Trust “recently serviced” without a receipt or a date
- Judge a film body by the outside; the light seals are inside
- Skip the sensor check on a digital M because the seller says it's clean
- Rush. A seller who won't give you ten minutes is telling you something
The checklist
| Check | What good looks like | Red flag |
|---|---|---|
| Rangefinder, horizontal | Patch lines up on a vertical edge at infinity (a distant roofline) with the lens hard against the stop | Doubled image at infinity, or the lens focuses past it |
| Rangefinder, vertical | Patch sits level on a horizontal edge; no step between the two images | Vertical offset. Annoying on film, wrong focus on digital |
| Close focus | Agrees with the lens scale at 0.7 m or 1 m | Aligned at infinity but off up close means the cam or roller is worn |
| Finder glass | Clear, bright patch, crisp frame lines | Haze, fog, a milky patch, or a rainbow sheen at the edges (balsam separation) |
| Shutter speeds | 1s sounds like a full second; 1/1000 sounds sharp and even | Slow speeds hang or sound sticky; fast speeds give an uneven, capping sound |
| Light seals (film) | Foam in the door channel is firm and black; mirror of the door is clean | Crumbs, tackiness or bare metal. Expect light leaks until replaced |
| Sensor (digital) | A few dust spots at f/16 against a white wall, nothing more | Scratches, a cluster of stuck pixels, or corrosion on an M9 sensor |
| Baseplate and battery door | Locks with a clean quarter turn; battery seats and ejects without a fight | Bent plate, stripped lock, a battery latch that needs a fingernail |
| Lens mount | Even brass wear on the bayonet; lens locks with a crisp click | Play in the mount, a release button that sticks, deep gouges |
| Frame-line selector | Lever moves through all three positions and lines change | Lever stiff, frozen, or lines don't switch |
The rangefinder itself
Start with the lens focused to infinity and look at something genuinely far away: a roofline, a telephone pole three blocks off. The ghost image in the central patch should sit exactly on top of the real one, left-to-right. Now pick a horizontal line, a window sill or the top of a fence, and check that the two images are level with each other. Vertical misalignment is the common one on bodies that have been knocked, and while it doesn't always ruin focus, it is the first thing you'll notice every time you raise the camera.
Then rack the lens to its closest distance and focus on a sharp edge close by. If the patch agrees at infinity but is off at a metre, the problem is in the cam follower, and that is a service job rather than a quick adjustment. A proper rangefinder adjustment is not expensive, but it is a reason to pay less.
"Infinity is easy. Close focus is where a tired rangefinder gives itself away."
Finder, shutter, and the sounds that matter
Point the finder at a bright sky and look for haze. A faint overall dimness is age and usually fine; a milky patch, or the rangefinder patch itself going weak and low-contrast, means the prism is on its way out. On older film bodies, a rainbow sheen or a crescent shape at the edge of the finder is the cement between glass elements letting go, and it only gets worse.
With the back open (film) or the lens off (digital), fire every shutter speed from 1 second up. The slow speeds should sound like a clock escapement running out cleanly; a 1-second that hangs for two, or a 1/8 that sounds like 1/2, points to dried lubricant. On the fast end, listen for an even sound at 1/1000. If the body has been sitting for years, a dragging slow-speed train is normal and a clean, lube, and adjust fixes it, but you should know that going in.
Film bodies: the inside counts
Open the back and look at the door channel. Light seals on most cameras are foam, and foam turns to tar after a few decades. On a Leica M the seals are mostly a felt strip and the door itself, so there is less to go wrong, but check the hinge side anyway. Then look at the pressure plate for scratches that will put tramlines down your negatives, and run the advance lever through a few strokes with the shutter cocking to feel for grinding. A take-up spool that doesn't grab film is a cheap fix but a maddening one to discover on a trip.
Digital bodies: sensor and electronics
Take the lens off, shine a small flashlight across the sensor at an angle and look for scratches in the cover glass. Then put the lens on, stop down to f/16, photograph a white wall or the sky slightly out of focus, and inspect the file at 100 percent. Dust you can live with. Scratches, lines, or a cluster of hot pixels are a different conversation. On an M9, M9-P or M-E, ask directly whether the sensor was replaced under Leica's corrosion programme, and look for a tiny, even stipple across the image that shows the cover glass has started to go.
Check the baseplate or battery door while you're there. The M10 and earlier use a removable plate; it should turn and lift cleanly, and the battery should drop in and eject without the latch sticking. The M11 dropped the plate, so test that the battery lock engages properly. Power the camera on, scroll the menus, and if the seller can show a shutter count, note it. Our M10 vs M11 guide covers what to expect from each.
What to bring to a meetup
Bring your own lens, ideally a 50mm you know is right, so you're testing the body and not an unknown lens. Bring a small flashlight for the sensor and finder, and a phone with the condition guide open so you and the seller are using the same words. If it's a film body, a cheap roll of film is worth carrying: you can load it, advance three frames, and feel the transport. Meet somewhere with daylight and a long view; a parking lot by a park works far better than a coffee shop.
And agree on a price before you start testing, with the understanding that what you find can change it. Most private sellers are honest and simply haven't looked this closely. That is the whole point of meeting in person on Aperture.market: you talk to the photographer who owned the camera, you check it yourself, and nobody pays a commission for the privilege.