By Ked · August 2026
August 2026
We run software that reads thousands of used lens listings a day. Its job is to look at a title and a description and work out three things: which lens this actually is, what it costs, and what shape it's in. Most of the time that's straightforward. Some of the time it isn't, and the reason it isn't usually has nothing to do with the lens being obscure. It's that the ad itself is unreadable.
Worth sitting with that for a second. Our parser has effectively memorized the entire Leica lens catalog, has no ego about admitting confusion, and will patiently reread a listing as many times as it takes. If a title still stumps something built for exactly this job, a person casually browsing eBay on their lunch break has no chance. What follows is a tour of the specific ways lens ads manage to hide the one fact a buyer actually needs, drawn from real listings we've had to flag and untangle by hand.
The single most common way a lens listing goes sideways is also the simplest to fix: the seller never says what mount it is.
"Leica Summicron Black Paint 50mm Rigid Late Model"
Is that M mount or the older screw mount (LTM)? Both existed. Both look similar in a thumbnail photo. And a buyer who owns an M-series body and buys the wrong one has purchased a lens that will not physically attach to their camera. This isn't a cosmetic omission, it's the load-bearing fact of the entire listing, and it's routinely the one thing left out, presumably because the seller already knows the answer and forgot that nobody reading the ad does.
The fix: mount goes in the title. Not the fourth sentence of the description. The title.
Also real, also unedited:
"Leica Summicrum-M 50mm f2 + UV Filter + HOOD + Caps Very Good Conditions"
"Leica 90mm f2.8 Elamrit M Mount Lens"
"Leica R – 28mm 2.8 PC Super Angolon"
"Summicrum" isn't a lens, it's a typo, but it's a big enough typo that automated matching (ours or eBay's own search) can miss it entirely, and so can a human buyer typing "Summicron" into the search bar and never seeing this listing at all. Same with "Elamrit" for Elmarit. The last one is genuinely funny: there's no such thing as a "Super Angolon," but there is a Schneider Super-Angulon, a well-known lens Leica rebadged for the R mount. One transposed vowel turned a specific, desirable, and identifiable lens into something that sounds like a knockoff energy drink.
The fix: the lens name is printed on the lens. Read it off the barrel, not from memory.
In the same corpus, the exact same lens shows up written as "50mm f/2," "2/50mm," "1:2/50mm," "5cm 1:2," and "f=5cm 1:2." Our parser has to normalize all five of those into one internal record, and on paper that looks like exactly the same kind of mess as everything above.
It isn't, and it's worth saying so. "1:2/50mm" is Leica's own official engraving, the aperture ratio and focal length exactly as they're printed on the barrel of the lens; a seller copying it off the glass isn't improvising. "5cm" instead of "50mm" is a holdover from when Leica measured focal length in centimeters on early Leitz nameplates, before millimeters became the standard. European listings will just as often write the aperture as "1:2,8" with a comma instead of a period, because that's the decimal separator in most of Europe. None of this is sloppiness. It's just where the lens, or the seller, is from.
And critically, none of it actually stops a buyer from understanding what's for sale. Once you've seen "1:2/50mm" once, you know it means the same thing as "50mm f/2," just with the two numbers swapped and a colon standing in for the word "aperture." That's a genuinely different problem from the mount that's never stated at all, or a model name spelled wrong enough that it's no longer searchable. A buyer can look past notation. They can't look past a fact that was simply never provided, or one that's been typo'd into something else entirely.
None of that is a defense of every number string we've seen, though. Some of it earns the sin label back:
"APO-TELYT-R f/280/400/560 mm (11841)"
"Elmarit-M f/2.8/21 mm ASPH"
"RARE f/4/135 Leica Objektv."
These aren't a regional dialect, they're just numbers glued together with slashes and no punctuation left to mark where one measurement ends and the next begins. The last two are readable if you already happen to know the aperture is f/2.8 or f/4 and the rest is focal length; the first one isn't readable at all unless you already know that the APO-Telyt-R was sold with three swappable front elements, giving it three possible focal lengths (280mm, 400mm, or 560mm) at a single fixed aperture. Written as "f/280/400/560mm," it reads exactly like a lens claiming an aperture of f/280, which doesn't exist and never has. You can't decode "1.4.50"-style chains the way you can decode "1:2/50mm," because there's no convention being followed, official or regional. It's just three numbers standing next to each other, daring you to guess which one is which.
A description, presented in full:
"Leica SUMMILUX-M 50mm f1.4 Black Lens #2220461 Made In Germany! NO RESERVE!!! DESCRIPTION Condition EX+ Description THIS AUCTION FOR USA BIDDERS ONLY! NO SHIPPING OUTSIDE USA! Optics: Clear, No Fungus, No Separation. Appearance: As shown in the pictures."
Read past the exclamation points and there are exactly two facts in there: no fungus, no separation. Everything else is either shipping logistics dressed up as urgency, or "as shown in the pictures," which is a way of saying the seller isn't going to describe the lens in words at all. Compare that to a shorter, calmer listing we also came across, for a lens focusing mount: "Rotation is smooth with just the right amount of torque." That's one sentence, no capital letters, and it tells a buyer more about actual mechanical condition than the entire Summilux listing above managed in five.
The fix: describe the glass (fungus, haze, scratches, separation, cleaning marks) and describe the mechanics (focus ring smoothness, aperture click detents, any grease that's migrated where it shouldn't be) in plain declarative sentences. Save the enthusiasm for a lens that's actually earned it.
This one isn't a knock on the seller. It's a genuinely well-written, detailed, honest description of an Elmar-C 90mm:
"Voll funktionsfähiger und gut gepflegter Zustand mit nur minimalsten äusseren Gebrauchsspuren. Alle Linsen sind sauber, keine Kratzer, Beschlag oder Fungus."
Translated, that says the lens is fully functional, well cared for, with only minimal cosmetic wear, and the glass is clean with no scratches, haze, or fungus. That's a great, honest, specific condition report. It's also written entirely in German on a listing plenty of English-speaking buyers will see, with no translation offered anywhere. The information a buyer needs is all there. It's just locked behind a language barrier the seller didn't think to flag, let alone bridge.
The fix: if you're listing somewhere with an international audience, a two-line English summary above or below the original costs almost nothing and opens the listing to everyone who'd otherwise scroll past assuming it isn't meant for them.
A sentence that appears, in some form, in an enormous number of listings, and communicates precisely nothing: no measurement, no comparison, no fact a buyer could act on. It's the verbal equivalent of a firm handshake. Reassuring in the moment, forgotten by the time the buyer scrolls to the next listing, because it didn't tell them anything the next listing couldn't also claim.
A real listing for a Summicron-R 90mm f/2, condition and terms both included, presented in the order the seller wrote them:
"Leica Leitz Summicron Canada 1.2 / 90 Serial Number 1681590 Lens Circa 1959 sold as found with some lens mold on front lens easily removed. We are selling the lens as found in working condition with some lens mold spots around the edges of the front lens. Thanks for looking, ALL ITEMS MUST BE PAID FOR WITHIN 72 HOURS OR THE ITEM WILL BE RELISTED, THERE ARE NO EXCEPTIONS. INSURANCE IS AN EXTRA EXPENSE AND MUST BE PAID BY THE BUYER. SHIPPING COSTS MAY VARY FROM THE EBAY CALCULATOR, ACCURATE SHIPPING COSTS WILL BE GIVEN WHEN AUCTION ENDS. WE DO NOT OFFER FREE SHIPPING ON ANY OF OUR ITEMS..."
Two sentences describe the actual lens: mold on the front element, sold as-is. Everything after "Thanks for looking" is payment enforcement and shipping policy, in caps, and it runs several times longer than the part that tells you what you're buying. We've also seen the reverse ordering, where the legal notice comes first: one listing template, copy-pasted across dozens of otherwise unrelated lenses, opens with "Before purchasing, please read this page in conjunction with the notes at the bottom of the page, and by placing an order and making payment, you agree to be bound by the product conditions and notes," followed by a paragraph on import duties, before the lens itself gets a single word.
Payment terms, insurance, and customs obligations are all legitimate things to disclose. The problem isn't that they exist, it's that they're allowed to compete with the condition report for the reader's attention, and in both examples above, they win. A buyer skimming for "does this lens have fungus" has to wade through a 72-hour payment deadline to find one sentence about mold.
The fix: condition first, in its own paragraph, uncapitalized. Policy boilerplate goes after it, ideally under its own small heading, so a buyer can find the part that answers "what am I buying" without reading the part that answers "how fast do I need to pay for it."
None of that requires a copywriter. It requires reading your own listing once, from the outside, as though you didn't already know what lens it was.
Once you know what to look for, a well-written ad and a well-priced one tend to go together, mostly because a seller who bothered to name the mount correctly usually also bothered to price it sanely. Check current listings and price guides on Used Lens Tracker, including the Summicron-M 50mm and Summilux-M 50mm pages if the typo section above left you second-guessing your own search terms. If you're shopping for a body to go with the glass, Used Camera Tracker covers that side of the market the same way.