{"product_id":"player-one-2-5mm-cs-mount-all-sky-lens","title":"Player One 2.5mm CS-Mount All-Sky Lens","description":"\u003ch3\u003e\u003cstrong\u003eProduct Overview\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe Player One 2.5mm CS-Mount All-Sky Lens is a very short focal-length lens that turns a small-format planetary or guide camera into an all-sky monitor. At 2.5 mm it delivers a 170° field of view on a 1\/2″ sensor — wide enough to take in nearly the entire sky in a single frame. It threads on via the standard CS mount and is metal-bodied. Player One optimizes it for their 1\/2″-format cameras, the Neptune series in particular.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eWho It's For\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThis is a good match if you run a 1\/2″-format planetary or guide camera (such as a Neptune-M, Neptune-C, or Neptune-C II) and want to point it at the whole sky for cloud, meteor, or aurora monitoring. It also works as a very wide finder-style lens on a guide camera.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eKey Features \u0026amp; Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e2.5 mm focal length:\u003c\/strong\u003e an ultra-short focal length that yields a 170° field on a 1\/2″ sensor.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCS mount:\u003c\/strong\u003e threads onto any CS-mount camera, including Player One planetary and guide cameras.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMatched to 1\/2″ sensors:\u003c\/strong\u003e the 170° coverage is stated for the 1\/2″ format — the Neptune series in particular.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMetal construction:\u003c\/strong\u003e a compact, durable barrel.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eOptical Design\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe all-sky field comes directly from the focal length and sensor size: a 2.5 mm focal length projected onto a 1\/2″ sensor spans roughly 170°, which is why such a short lens captures the whole dome of the sky rather than a narrow patch. The CS mount is the standard machine-vision lens interface (a C mount shortened by 5 mm of flange distance) used by compact astronomy cameras, so the lens seats at the correct back-focus without an adapter on a CS-mount body.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eRecommended Uses\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eAll-sky monitoring — clouds, meteors, satellites, aurora — with a 1\/2″ planetary camera, and use as a wide-field lens on a guide camera.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eCompatibility and Accessory Notes\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eThe lens uses a CS mount and is matched to 1\/2″-format sensors such as the Neptune series. On a larger sensor the 170° figure no longer applies and the image circle may not fill the frame. If you are pairing it with a different camera and are unsure of the fit, send us your camera model and we will confirm it with you.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eGood to Know Before You Order\u003c\/strong\u003e\u003c\/h3\u003e\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003e1\/2″ format:\u003c\/strong\u003e the 170° field is specified for a 1\/2″ sensor (Neptune series); a larger sensor changes the coverage.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCS mount:\u003c\/strong\u003e it needs a CS-mount camera; a C-mount body requires a 5 mm CS-to-C spacer, sold separately.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eLens only:\u003c\/strong\u003e the camera and any mounting are not included.\u003c\/li\u003e\n\u003c\/ul\u003e\u003ch3\u003e\u003cstrong\u003eFrequently Asked Questions\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003e\u003cstrong\u003eIs it difficult to set up?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eNo — thread it onto a CS-mount camera and adjust focus at the lens. Nothing else is required.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat camera is it for?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eA 1\/2″-format planetary or guide camera, such as the Player One Neptune-M, Neptune-C, or Neptune-C II.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eWhat field of view does it give?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003e170° on a 1\/2″ sensor — an all-sky view.\u003c\/p\u003e\u003cp\u003e\u003cstrong\u003eHow is it different from the 2.1mm lens?\u003c\/strong\u003e\u003c\/p\u003e\u003cp\u003eThe 2.1mm lens is matched to the smaller 1\/3″ format (Mars series) and gives a 150° field; this 2.5mm lens is matched to the 1\/2″ format and gives 170°.\u003c\/p\u003e\u003ch3\u003e\u003cstrong\u003eBottom Line\u003c\/strong\u003e\u003c\/h3\u003e\u003cp\u003eIn short: a 2.5 mm CS-mount lens that gives a 170° all-sky field on a 1\/2″ sensor, matched to the Player One Neptune series for whole-sky monitoring.\u003c\/p\u003e","brand":"Player One Astronomy","offers":[{"title":"Default Title","offer_id":53834290987119,"sku":"25LENS","price":30.8,"currency_code":"CAD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0686\/0049\/6239\/files\/2.5lens-2.jpg?v=1784239710","url":"https:\/\/ontariotelescope.com\/products\/player-one-2-5mm-cs-mount-all-sky-lens","provider":"Ontario Telescope and Accessories","version":"1.0","type":"link"}