Here's the thing about the Summaron 35mm f/3.5: it's not the lens people brag about at "camera club" meetings or in YouTube reviews— the Summicron and Summilux get that honor — but it's the lens quiet collectors actually hunt for, because it's one of the last honest doors into real Leitz glass under $500. At $499.99 listed currently by National Camera Exchange, it is squarely in that sweet spot.
The lens itself has a slightly tangled birth story (records seem a little inconclusive). According to Van Hasbroeck's Leica history, it was announced in 1946 but didn't actually reach photographers until 1949, when it took over from the older 35mm f/3.5 Elmar as Leica's wide-angle option. The Smithsonian's own collection notes confirm the timing gap directly: their 1937 Leica IIIa came with an Elmar because, as the museum puts it, the 35mm f/3.5 Summaron was not manufactured until 1949 and is not contemporary with the camera. Once it did arrive, Leitz built a lot of them — over 100,000 units (which is a lot for Leica!), making it one of the most common Leica wide-angle lenses ever made, produced across screw-mount and M-mount bodies with the same six-element, four-group optical formula and a ten-blade aperture that renders unusually round out-of-focus highlights for a lens this old.
The quirky part — and the reason your listing calls out an 'ocular viewfinder' — is the goggles. When Leica launched the M3 in 1954, its viewfinder only showed 50mm, 90mm, and 135mm frame lines, with no accommodation for anything wider. Rather than force 35mm shooters to tack on an external finder, Leitz displayed a goggled version of the Summaron at Photokina — a lens that could be used with the regular M3 viewfinder via an optical viewing unit that slides over the lens mount, with one component correcting the M3's finder to match the 35mm field and the other adjusting the rangefinder image so both remain the same size. It's a genuinely odd little solution — essentially strapping a mini periscope onto the lens barrel — and it's the reason these goggled Summarons look so distinctive on a shelf.
There's a well-known quirk that trips up new owners: pull the goggles off and the lens locks at infinity focus. Collectors who've dug into this insist it isn't a defect — the fact that the lens is locked at infinity with the goggles removed is not an engineering error, but Leitz's way of telling the user that infinity is the only setting at which the rangefinder stays accurate without them. It's a small detail, but it's the kind of thing that makes vintage Leica ownership feel like decoding a puzzle instead of just buying a camera part.
As for why collectors still care in 2026: by the late 1950s Leica had moved on. 1958 marked the first time Leica users had several 35mm lenses to choose from, when the Summaron 2.8 and Summicron 2.0 hit the market alongside the older Summaron 3.5, with the first Summilux following two years later — which meant the slower f/3.5 became, and has remained, the budget-friendly entry point into Leitz 35mm glass. That reputation holds up in real transactions, too: one collector writing in early 2025 noted paying $550 with a fresh cleaning, lubrication and adjustment for the f/3.5 — literally half the price of the f/2.8 version. Optically, nobody's pretending this is a modern lens — reviewers consistently describe it as a soft glow wide open with a gentle, slightly dreamy quality, sharpness improving markedly as the lens is stopped down, and there's a known tendency toward internal haze that affects contrast and flare, though it can often be cleaned. That's not a flaw so much as a signature — plenty of black-and-white shooters buy this lens specifically for the vignetting and lower-contrast rendering it's known for. I couldn't find a solid, verifiable record tying this specific lens to a famous name — but its decades as a common, affordable, genuinely worked wide-angle is its own kind of legend.