CTO-028 is a Color Temperature Filter designed to add a warming shift while keeping the spectrum smooth, stable, and visually natural. It gently reduces blue energy relative to longer wavelengths and maintains a controlled rise through the visible range so reds and ambers transmit more strongly. This creates a warm balance change that helps lighting and camera systems move toward a warmer white point without sharp spectral edges that can introduce color artifacts.
Key advantages
Warming color temperature shift – moves correlated color temperature warmer by reducing blue content relative to red and amber.
Smooth spectral response – avoids sharp transitions that can cause banding, unnatural hues, or channel artifacts.
Strong long-wavelength throughput – preserves reds and ambers for healthier skin tones and richer warm highlights.
Stable, repeatable tuning – consistent performance supports matching across fixtures and production batches.
Hard-oxide durability – ion-assisted coating options resist heat, humidity, solvents, and repeated cleaning.
Flexible formats (KUPO custom-made optical filters) – round, square, or complex blanks from 5 mm to 450 mm, 0.21–3.8 mm thick, on Borofloat®, soda-lime, Schott D263 T, or Corning Eagle XG glass.
Typical applications
Stage and architectural lighting – warm LED or discharge sources toward a tungsten-like feel while keeping output smooth.
Broadcast and studio fixtures – tune correlated color temperature to match cameras, sets, or mixed lighting environments.
Film and photography – warm key or fill lights for flattering tones and consistent white balance.
Retail and exhibition lighting – enhance warm materials such as wood, textiles, and food displays while maintaining a natural look.
Optical systems needing warming – introduce controlled warmth without harsh spectral discontinuities.
Need prototypes fast or production volumes soon? CTO-028 filters can be coated, diced, and shipped to your exact specifications quickly, and because KUPO can custom-make optical filters, we can tune warming strength, substrate, thickness, and angle-of-incidence targets to match your light source and optical stack.