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Rectangular dark blue glass filter in Cokin A-Series frame

Cokin

Cokin A21 Dark Blue Conversion/Cooling Filter (80B) A-Series camera filter

SKU CH-6AQZ-9K2M4

Dark blue 80B filter suppresses tungsten orange tones for atmospheric daylight-film photography

  • Suppresses orange tungsten tones for atmospheric images
  • Dark blue glass adds depth with sculptured shadows
  • Maintains original colour balance while cooling the scene
  • A-Series system enables quick filter stacking and swapping
  • Single-coated blue glass construction for durable optical quality

Purpose & User

The Cokin A21 Dark Blue Conversion/Cooling Filter (80B) is a rectangular camera filter made for photographers using daylight-balanced film under tungsten or halogen lighting. It belongs to the A-Series system, which lets users stack or swap filters quickly without tools. The single-coated blue glass suppresses strong orange tones from artificial light sources while preserving the original colour balance of the scene.

Filter Factor & Wratten Rating

The filter carries an 80B designation, the single specification that tells you how much cooling correction it applies to tungsten light. This rating matches the needs of standard daylight film in typical indoor or street-lit environments. The A-Series mount ensures it fits the same holder as the medium blue A021 and light blue A022 filters for combined use.

Sustained Shooting Behaviour

Under continuous use the single-coated glass resists flare and ghosting when bright point lights such as party bulbs or illuminated monuments fill the frame. Shadows retain sculptured depth without turning muddy, and the coating cleans easily between long sessions. The rectangular shape covers wide-angle lenses without vignetting when mounted in the A-Series holder.

Highlights

  • Suppresses orange tungsten tones for atmospheric images
  • Dark blue glass adds depth with sculptured shadows
  • Maintains original colour balance while cooling the scene
  • A-Series system enables quick filter stacking and swapping
  • Single-coated blue glass construction for durable optical quality

Specifications

No published specifications for this item yet.

Questions about this item

What does the 80B designation mean when I use this filter on my camera?

The 80B designation indicates this filter converts tungsten or halogen lighting to match daylight film, suppressing strong orange tones for natural colour balance.

How does the A-Series mount affect which filter holders I can use?

The rectangular A-Series design slides into any Cokin A-Series holder, letting you stack or swap this filter with other A-Series filters quickly.

What physical size is the glass so I know it fits my holder?

The filter is a rectangular blue glass plate made to the standard A-Series dimensions used across the Cokin A-Series system.

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