A vintage lens has spent forty or fifty years in drawers, bags and attics. Most still work well, but the faults that ruin one are often hard to see in a normal product photo. The good news is that you can check most of them before you pay, from the right photos and a couple of questions. This guide goes through each common fault, what it looks like, and the few things you can only judge once the lens is in your hands.
Ask for the flashlight photo
The most useful photo you can ask for is one taken through the lens with a bright light behind it. Ask the seller to open the aperture all the way, shine a flashlight into the back of the lens, and photograph through the front at a slight angle. Then ask for the same thing from the other side. Dust, haze, fungus and separation all light up this way, even when they're invisible in a studio shot.
A seller who knows lenses will usually have this photo already, or take it without fuss. If the listing only shows the outside of the barrel, ask. It's a normal request.
Haze
Haze is a milky fog on or inside the glass. It lowers contrast, and with a light source in the frame it adds a glow. One common cause is lubricant from the focusing or aperture mechanism that evaporates over the years and settles on the inner surfaces. A 35mmc writer found exactly that in a Canon 50mm f/1.2, with haze from aperture-lubricant out-gassing that cleaned off the inner glass.
In the flashlight photo, haze shows as an even grey fog across an element. Light haze on an outer surface wipes off. Haze inside the lens means taking it apart, which some owners do themselves and others pay a technician for. Allow for that, or pick a clearer copy.
Fungus
Fungus looks like fine branching threads, spots, or a web, usually starting at the edge of an element. Wikipedia's article on lens fungus says it doesn't eat the glass itself. It feeds on organic material on or around it, like fingerprints, grease and the cement between elements, and it thrives in warm, humid storage. Its waste can etch the glass coatings, and that damage can stay after the fungus is cleaned off.
A small spot near the edge of a common lens may not affect pictures much. A web across the middle, or fungus on a coated surface you can't reach, is a reason to pass. Whatever you buy, store it somewhere dry with some airflow, since damp, still air is what fungus needs.
Balsam separation
Many lenses have two elements glued together into one group. Camera-wiki explains that when the cement fails, air gets between the elements and the gap splits light into colors, like a film of oil on water. In a photo through the lens you'll see a rainbow patch or ring, often starting at the edge.
People call it balsam separation after Canada balsam, the natural resin once used as optical cement. Wikipedia says synthetic adhesives replaced balsam during the Second World War, so most lenses in our catalog use a newer cement. They can still separate. Separation is hard and costly to fix, so treat it as a serious fault.
Scratches and cleaning marks
Cleaning marks are fine hairlines in the coating left by years of wiping. They show up in strong light and rarely show up in pictures. Scratches are deeper, and you can often see them in normal light. A small front scratch usually matters less than you'd think, and a lens hood helps by keeping light from glinting off it. A mark on the rear element shows up more readily than the same mark on the front. Ask for a clear photo of both ends of the lens.
Oily aperture blades
Oil from the focusing helicoid can creep onto the aperture blades. Oily blades look shiny or spotted, and they can stick, so the aperture closes slowly or not at all. A 35mmc writer found a Chinon lens's iris stuck wide open, and taking out the rear group showed very oily blades, which he cleaned with isopropyl.
Ask for a photo with the aperture set to f/8. The blades should look dry and matte, and evenly closed. For lenses with an automatic aperture pin, like many M42 lenses, ask the seller to press the pin or switch the lens to manual and check the blades snap shut and open again.
Mount and version
Make sure the lens is the version you think you're buying. Read the name ring and the back of the lens in the photos.
- Canon FD. A silver ring at the base means breech-lock FD, a small release button means New FD. Our FD vs New FD guide covers the rest.
- Nikon. Wikipedia says AI lenses from 1977 added a meter coupling ridge on the aperture ring, and AI-S from 1981 marks the smallest aperture in orange. Older pre-AI lenses lack the ridge. See the Nikon F mount page.
- Minolta. MC lenses date from 1966 and MD lenses from 1977, and the label says which. See the Minolta mount page.
- M42. Check for an auto pin and an Auto/Manual switch, which decide what adapter you need.
- Leica R. Wikipedia explains that lenses carry 1, 2 or 3 cams, or are R-only. This matters on Leica film bodies more than on an adapter. See the Leica R mount page.
Japanese dealer grades
Many lenses for sale ship from Japan, and their listings use grades like Mint-, Near Mint, Exc+5 or Exc+++. These are each seller's own opinion on their own scale. There's no shared standard behind them. A 35mmc writer bought a camera from Japan described as near mint and found it had been knocked and glued back together. One reader's advice in reply was to trust the photos only, since the written descriptions are pretty generic.
So read the grade as a starting point and ask for the flashlight photos. Clear photos and a specific description of the glass tell you more than any grade.
What you can only check on arrival
- Focus feel. The ring should turn smoothly with even resistance. Grinding or a gritty feel can mean sand or dried grease.
- Infinity focus. Focus on something far away on your adapter. The image should get sharp just before the infinity stop.
- Aperture action. Turn the aperture ring on the adapter and watch the blades move through every stop.
- Wobble. Hold the barrel and gently rock the front. There shouldn't be any play.
- Test shots. Shoot wide open toward a bright light. Haze and separation show up as glow or low contrast.
Buy from sellers who accept returns, so you can send back a lens that fails these checks. If you want to start with lenses that are easy to inspect and adapt, the Helios 44-2 and New FD 50mm f/1.8 are good places to begin. Our methodology explains how we pick listings, and you can browse what's for sale now.
