The vintage lens buying checklist

A vintage lens is a fifty-year-old mechanical object with glass inside, and every fault it can have is visible with a flashlight, a white wall, and two minutes of handling. The checklist below runs in the order that saves the most money: identify the variant, check the price, inspect the glass, inspect the mechanics, confirm the mount, then test the lens when it arrives. It applies to any manual lens in the catalog, from a Hexanon 50mm f/1.7 to a Summicron-R.

1. Identify the exact variant before you look at the price

Many lenses share a name across versions that differ in optics, coating, or mount, and the versions sit in different price bands. The Super-Takumar 50mm f/1.4 exists as a collectible 8-element early version and a common 7-element later one. A Nikkor-S 50mm f/1.4 may be original pre-AI or factory AI-converted. A Canon FD 50mm f/1.4 is a chrome-nose breech-lock S.S.C. or a later New FD. Ask for a photo of the name ring and the serial number and settle the variant first. The Helios 44-2 guide shows how much a single name can hide.

2. Check the price against a real range

Every catalog page states a low, typical, and high used value with its basis. A price well below the low end usually means an undisclosed fault, a parts lens, or a misidentified variant. A price above the high end needs a reason: a scarce variant, a documented service, or a dealer warranty. Budget for a clean, lube, and adjust (CLA) on any lens over forty years old that has not had one; a simple prime typically costs 80 to 150 dollars to service, and that figure belongs in your maximum bid.

3. The flashlight test: glass

Open the aperture fully, shine a bright flashlight through the rear of the lens toward a dark background, and look through the front. Then reverse it. Tilt the lens so the light rakes across each element. You are looking for five things:

• Fungus: branching filaments or a spider-web pattern on an internal surface, sometimes with a frosted patch. Small early growth can be cleaned; established fungus etches the coating and is permanent. Walk away from anything more than a few filaments.
• Haze: a uniform fog on an internal surface that lowers contrast and produces glow into shadows. Most haze is outgassed lubricant and cleans off in a CLA, but on some cemented groups it is balsam degradation and does not. Ask whether it wipes off.
• Separation: a rainbow sheen, a Newton's-ring pattern, or a crescent at the edge of a cemented doublet where the cement has let go. It cannot be fixed cheaply. Light edge separation on a rear group affects nothing in the image; central separation does.
• Scratches and cleaning marks: fine swirls on the front element from decades of wiping. On the front they cost little except flare into the sun. On the rear element, close to the aperture, they matter more. A single deep scratch matters less than a thousand light ones.
• Coating wear: patches where the coating has been polished away show as a colour change under the raking light. Cosmetic on the front, contrast-lowering if extensive.

4. The mechanics

• Aperture blades: stop down through the range and look for oil on the blades. Wet or stained blades on an automatic lens make the diaphragm sluggish, which means wrong exposures on a film body and slow response on any body. On a preset or manual lens oil is a warning about the grease elsewhere but not a functional fault.
• Aperture ring: it should click evenly with no free play. A ring that turns without changing the blades has a broken linkage.
• Focus ring: it should turn smoothly with even resistance from close focus to infinity. Stiff in the cold and loose in the warm means old grease; gritty means dirt in the helicoid; a wobble means worn threads.
• Filter ring: a dent means a drop. A drop can decenter an element without any other visible sign, so a dented lens needs the wall test below before you keep it.
• Mount: check for bent bayonet lugs, chewed screw threads, and missing screws. Inspect the rear of M42 lenses for the state of the auto pin.

5. Read the seller's language

Certain phrases carry information. Clear glass without mention of fungus, haze, or separation means the seller did not look. No fungus that I can see means no flashlight was used. Untested or as-is means a fault is known. Minor dust inside is normal and harmless. Some yellowing on a 1960s fast fifty is not haze; it is thoriated glass and clears with UV, as explained in thoriated glass and yellowing. A seller who names the variant, photographs the glass with a light through it, and states the aperture behaviour has done the inspection for you.

6. Understand the grades

7. Confirm the mount before you pay

• Nikon F: pre-AI lenses cannot mount on many later Nikon film bodies and DSLRs without modification. On a mirrorless adapter they work as-is.
• Canon: FL and FD look alike; FL meters stopped down only. FD lenses need an adapter with a locking ring on mirrorless.
• Pentax: the K bayonet and M42 thread are different mounts with the same register. An A position on the aperture ring needs to be off A on an adapter.
• Konica AR: the AE or EE lock must be released for manual aperture control.
• M42: preset, manual, and automatic lenses need different adapter styles. See adapting M42 lenses to Sony E.
• Leica R: 1-cam, 2-cam, 3-cam, R-only, and ROM versions all adapt, but only 3-cam works on every Leica body if you also shoot film.

8. Test it when it arrives

1. Focus on a distant object and confirm the lens reaches infinity on your adapter with the ring at or just before the infinity mark.
2. Shoot a flat brick wall or newspaper square to the camera at the widest aperture and at f/8. Compare all four corners. One soft corner at both apertures means a decentered element.
3. Shoot the same scene at every marked aperture. Exposure should change by one stop per stop; if it does not, the blades are sticking.
4. Shoot a bright light source at the frame edge to check for flare and internal reflections that fungus or haze cause.
5. Do all of this inside the return window.

A lens that passes these eight steps is a lens you can price, adapt, and shoot with confidence. The catalog pages give you the variant details and value ranges for step one and two; the flashlight gives you the rest.