CTO-009 Warming color-correction filter

CTO-009 is a warming color-correction filter that reduces blue-to-green light relative to longer visible wavelengths. Use it to adjust a broadband source’s color balance; the final effect depends on the lamp spectrum.

Measured wavelength range: 380-780 nm
400-500 nm: 61.3% average transmission
500-600 nm: 70.7% average transmission
600-700 nm: 83.4% average transmission
Custom options: Wavelength response, dimensions and operating conditions

Values shown are sample measurements. Final specifications are agreed for your order.

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Warming color-correction filter (CTO-009)

CTO-009 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 61.3% over 400-500 nm, 70.7% over 500-600 nm, 83.4% over 600-700 nm. The resulting light output also depends on the lamp spectrum.

Optical performance

Measured wavelength range: 380-780 nm. Performance outside this measured interval is not established by this curve.
400-500 nm: Approximately 61.3% average transmission; the range is 59.7-65.4% in the measured curve.
500-600 nm: Approximately 70.7% average transmission; the range is 63.6-77.8% in the measured curve.
600-700 nm: Approximately 83.4% average transmission; the range is 77.8-87.7% in the measured curve.
Customization: We can customize stock and sample-book designs. Tell us the wavelength response, size and operating conditions you need.

These 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.

Applications to consider

Stage and architectural lighting: 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.
Film and photographic lighting: 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.
Fixture development: Use the measured color-shaping profile to compare available coatings. Confirm the required color temperature, tint, throughput and operating conditions on the assembled fixture.

Choosing this filter

Evaluate the filter together with the intended light source. Color temperature, tint, color rendering and luminous output depend on that combination.
Tell us the size, shape and working angle you need, along with the temperature conditions inside the fixture.

Custom options

Start 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.

Transmission spectrum

Questions about CTO-009

What do the measured values tell me about CTO-009 on white light?

The sample averages are 61.3% over 400-500 nm; 70.7% over 500-600 nm; 83.4% 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.

Can I predict the brightness after CTO-009 from these three averages?

The 61.3% average over 400-500 nm gives each measured wavelength equal weight; an LED may concentrate its output in a narrow peak within that interval. Look up your actual emission wavelengths on the CTO-009 curve, or evaluate a sample with your source and detector.

Discuss this filter with KUPO - include the product reference, source wavelength, working angle and required dimensions.