{"product_id":"cto-042","title":"CTO-042 Warming color-correction filter","description":"\u003cnav aria-label=\"Product family\"\u003e\u003cp\u003e\u003ca href=\"\/collections\/all-products\"\u003eAll optics\u003c\/a\u003e \/ \u003ca href=\"\/collections\/color-temperature-orange-warming-filter\"\u003eColor Temperature Orange Filters\u003c\/a\u003e\u003c\/p\u003e\u003c\/nav\u003e\u003cstyle\u003e\n.ko-reviewed{color:#222;font-family:inherit;line-height:1.65;overflow-wrap:anywhere}\n.ko-reviewed *{box-sizing:border-box}.ko-reviewed h2,.ko-reviewed h3{color:#005F96;line-height:1.3}\n.ko-reviewed h2{font-size:24px;margin:0 0 1rem}.ko-reviewed h3{font-size:19px;margin:1.7rem 0 .65rem}\n.ko-reviewed p{margin:.6rem 0 1rem}.ko-reviewed ul{padding-left:1.25rem;margin:.6rem 0 1rem}\n.ko-reviewed li{padding-left:.15rem;margin:.55rem 0}.ko-reviewed .ko-note{border-left:3px solid #c9dae4;padding:.65rem 1rem;background:#f7fafc;font-size:.95em}\n.ko-reviewed a{color:#005F96;text-decoration:underline}\n\n@media(max-width:480px){.ko-reviewed h2{font-size:22px}.ko-reviewed h3{font-size:18px}.ko-reviewed .ko-note{padding:.65rem .8rem}}\n\u003c\/style\u003e\u003csection class=\"ko-reviewed\"\u003e\u003ch2 class=\"ko-catalog-description-title\"\u003eWarming color-correction filter (CTO-042)\u003c\/h2\u003e\n\u003cp\u003eCTO-042 is a warming color-correction filter. It reduces blue-to-green light relative to longer visible wavelengths. This can give a suitable broadband light source a warmer balance. Average transmission in the sample is 18.2% over 400-500 nm, 42.1% over 500-600 nm, 87.4% over 600-700 nm. The resulting light output also depends on the lamp spectrum.\u003c\/p\u003e\n\u003ch3\u003eOptical performance\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eMeasured wavelength range:\u003c\/strong\u003e 380-800 nm. Performance outside this measured interval is not established by this curve.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e400-500 nm:\u003c\/strong\u003e Approximately 18.2% average transmission; the range is 8.3-54.1% in the measured curve.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e500-600 nm:\u003c\/strong\u003e Approximately 42.1% average transmission; the range is 29.8-62.3% in the measured curve.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003e600-700 nm:\u003c\/strong\u003e Approximately 87.4% average transmission; the range is 62.3-94.7% in the measured curve.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMeasured edge at 50% transmission:\u003c\/strong\u003e Approximately 583.9 nm. Interpolated absolute-transmission crossing, checked against the factory summary. \u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eCustomization:\u003c\/strong\u003e We can customize stock and sample-book designs. Tell us the wavelength response, size and operating conditions you need.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003cp class=\"ko-note\"\u003eThese values come from the measured samples and help you choose a starting design. We will agree the final specification for your order. Custom versions have their own specifications and measured curves.\u003c\/p\u003e\n\u003ch3\u003eApplications to consider\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eStage and architectural lighting:\u003c\/strong\u003e Try it when you need a warmer balance from a broadband white light source. Check the color and brightness with your actual light source before choosing a filter.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFilm and photographic lighting:\u003c\/strong\u003e Consider it for warming a daylight or cool-white fixture toward another light in the scene. Measure the color match with the actual fixtures and camera.\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eFixture development:\u003c\/strong\u003e Use the measured color-shaping profile to compare available coatings. Confirm the required color temperature, tint, throughput and operating conditions on the assembled fixture.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eChoosing this filter\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eEvaluate the filter together with the intended light source. Color temperature, tint, color rendering and luminous output depend on that combination.\u003c\/li\u003e\n\u003cli\u003eTell us the size, shape and working angle you need, along with the temperature conditions inside the fixture.\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003ch3\u003eCustom options\u003c\/h3\u003e\n\u003cp\u003eStart with this stock or sample-book design, then tell us what you need to change. We can discuss the wavelength bands, transmission, blocking, angle, glass material, size and operating conditions with you, and agree a specification for your custom filter.\u003c\/p\u003e\u003c\/section\u003e\u003ch3\u003eTransmission spectrum\u003c\/h3\u003e\u003ciframe src=\"https:\/\/charts.kupooptics.com\/CTO-042.html\" title=\"CTO-042 transmission spectrum with wavelength readout\" loading=\"lazy\" width=\"100%\" height=\"880\" style=\"border:0;width:100%;height:clamp(640px,calc(43vw + 320px),880px);\" referrerpolicy=\"no-referrer-when-downgrade\"\u003e\u003c\/iframe\u003e\u003csection class=\"ko-reviewed ko-product-faq\" aria-label=\"Product questions\"\u003e\u003ch2\u003eQuestions about CTO-042\u003c\/h2\u003e\n\u003ch3\u003eHow does CTO-042 change the balance of blue and red light?\u003c\/h3\u003e\n\u003cp\u003eThe sample averages are 18.2% over 400-500 nm; 42.1% over 500-600 nm; 87.4% over 600-700 nm. Compare those bands rather than treating the filter as a uniform dimmer: the relative transmission is what changes the light balance.\u003c\/p\u003e\n\u003ch3\u003eWhat does the 50% crossing near 583.9 nm mean for CTO-042?\u003c\/h3\u003e\n\u003cp\u003eIt identifies where this measured curve crosses 50% transmission. It is useful for comparing the spectral transition, but it does not give a fixed color-temperature shift or the total light output from your lamp. For CTO-042, use the band averages above together with your source spectrum.\u003c\/p\u003e\u003c\/section\u003e\u003cp\u003e\u003ca href=\"\/pages\/contact\"\u003e\u003cstrong\u003eDiscuss this filter with KUPO\u003c\/strong\u003e\u003c\/a\u003e - include the product reference, source wavelength, working angle and required dimensions.\u003c\/p\u003e\u003cstyle\u003e#MainContent .ko-reviewed\u003eh2.ko-catalog-description-title{font-size:27px;font-weight:500;line-height:1.4;letter-spacing:-.01em;color:#0c324b;background:#f0f6f9;padding:20px 24px;}#MainContent .ko-reviewed\u003eh2.ko-catalog-description-title+p{border-bottom:0;}@media(max-width:650px){#MainContent .ko-reviewed\u003eh2.ko-catalog-description-title{font-size:24px;}}\u003c\/style\u003e","brand":"KUPO Optics","offers":[{"title":"Color Temperature Orange (Warming) Filter \/ 1\/2 CTO","offer_id":48516666687743,"sku":"CTO-042","price":0.0,"currency_code":"TWD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0818\/8651\/1359\/files\/cto-042-spectrum.jpg?v=1778712844","url":"https:\/\/kupooptics.com\/products\/cto-042","provider":"KUPO Optics","version":"1.0","type":"link"}