{"product_id":"borg-4257-m57-m42p1conversbarrel","title":"BORG 4257 M57-M42p1conversbarrel","description":"\u003ch2\u003eBORG 4257 M57-M42p1 conversion barrel | Connects two thread sizes\u003c\/h2\u003e\n\u003cp\u003eIts defining decision is a direct conversion between M57 and M42 P1: the BORG 4257 is made to bridge components with those two thread interfaces. That’s useful when your optical setup is built from sections that don’t share the same connection size. Rather than changing a larger part of the setup, you can use this barrel at the junction where the M57 and M42 P1 components meet. It suits photographers and other optical-system users who already work with these thread sizes and need a specific connection between them. Think of it as a small, purpose-led link in a modular assembly, not a lens with a stated focal length or shooting role. Its value is practical and precise: it addresses this particular mismatch. If your setup uses different thread sizes, this isn’t the conversion to reach for.\u003c\/p\u003e\n\u003cdiv class=\"specialist-note\"\u003e\n\u003ch3\u003eSpecialist Note\u003c\/h3\u003e\n\u003cp\u003eSetup stays straightforward when the two parts you need to join are M57 and M42 P1: this barrel gives you that specific transition without turning the job into a hunt for a different-sized component. I’d use it when laying out a modular optical assembly with an M57 section at one end and an M42 P1 component at the other; the result is a more continuous connection between those pieces. The useful detail is how exact the pairing is: M57 on one side of the conversion, M42 P1 on the other. It suits someone who knows the thread sizes in their setup. Just keep its role in mind—it solves this junction, not every thread mismatch.\u003c\/p\u003e\n\u003c\/div\u003e\n\u003ch3\u003eTechnical Specifications\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eBrand: BORG\u003c\/li\u003e\n\u003cli\u003eModel: 4257\u003c\/li\u003e\n\u003cli\u003eConversion: M57 to M42 P1\u003c\/li\u003e\n\u003cli\u003eProduct type: Conversion barrel\u003c\/li\u003e\n\u003c\/ul\u003e","brand":"BORG","offers":[{"title":"Default Title","offer_id":57563659010388,"sku":"BG-4257","price":38.03,"currency_code":"EUR","in_stock":false}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0780\/2493\/3716\/files\/BG-4257_01.jpg?v=1791804917","url":"https:\/\/www.htf-store.com\/de\/products\/borg-4257-m57-m42p1conversbarrel","provider":"Hard to Find Camera Store","version":"1.0","type":"link"}