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TELESCOPE FILTER INFORMATION

Telescope Filter Colour Chart & Comparison

Telescope filters most commonly consist of a circular glass threaded ring that attaches to the bottom of the eyepiece, the glass filter can be coated with a large variety of options from colour dyes in gelatine to exotic metal oxides. Each type of coating modifies the behaviour of the glass and offers a variety of optical improvements and enhancements.

The filter model numbers / codes are called the Wratten Number, which are named after the founder of the first photography company and British inventor Frederic Wratten. The numbers are just a reference number however the letter indicates an increase in filter strength.

Below we have listed a few of the most popular filters used for astronomy viewing and photography.
Not all the Wratten numbers are shown.

Wratten NumberFilter StyleFilter TypeFilter ColourVisual, Photography
Or Both
MercuryVenusMarsJupiter SaturnUranusNeptuneMoonNebulaGalaxiesClusters
W12ColourLongpassYellow   YesYes YesYes    
W15Colour Deep Yellow   YesYes       
W21ColourLongpassOrange Yes Yes    Yes   
W23AColourLongpassLight Red Yes Yes        
W25ColourLongpassRed YesYesYes        
W29ColourLongpassDeep Red Yes Yes        
W32Colour Magenta    YesYes      
W38AColourBandpassDark Blue  Yes Yes       
W46Colour Blue  Yes         
W47Colour Blue  Yes Yes       
W57ColourBandpassGreen Yes YesYesYesYesYesYes   
W58ColourBandpassGreen   Yes        
W64Colour Blue Green   Yes        
W80AColourBandpassLight blue    YesYes  Yes   
 Light Pollution Reduction (LPR)           YesYesYes
 Moon Filter              
 Neutral Density    YesYesYes   Yes   
 High Contrast (UHC) / Contrast Booster     YesYes   Yes   
 Infra red (IR) Cut  Photography  YesYesyes    YesYes
 Infra red (IR) Pass  Both  YesYesYesYes Yes   
 Ultraviolet (UV)              
 Fringe KillerBandpass Both  YesYesYes  Yes