Chroma Technology 50mm Square Unmounted OIII 5nm Narrowband Filter

Chroma Technology filters are built to exacting specifications and made in the USA at the Chroma Technology facility in Vermont. This employee owned company has been specializing in sputtered optical filters and coatings for demanding applications providing optical filters and coatings for both scientific and astronomy settings. Their filters are precision made with exceptionally hard coatings that remain stable in temperature fluctuations and humidity for reliable filter performance. AR anti-reflective coatings ensure that no reflections obscure the image for perfect results.

Chroma manufacture the highest quality astronomy filters with durable, sputtered hard coatings using single substrates of the best glass, eliminating the need for laminations. All primary filter coatings are applied on the front surface and anti-reflection coatings on the rear surface to prevent ghosting and to maximise transmission. Chroma astronomical filters are used worldwide in research and amateur applications. 

Highly precise and accurate, the passbands of these filters remain spectrally stable and do not drift in response to extreme temperature fluctuations or changes in humidity.

All filters may be used with focal ratios of f/4 or slower. For optics faster than f/4 then due to the spectral shift we recommend using the 5nm filters instead.

Chroma’s OIII filters isolate the 500.7nm primary emission line of doubly ionised oxygen. After H-alpha, this is the next most common emission when imaging nebulae

Cleaning and Handling

Handle coated pieces by the edges only. Clean gently only if necessary. Loose particles should be removed with a bulb puffer or filtered, pressurised air cleaner. If necessary, gently wipe surface using anhydrous alcohol and lint-free lab towels. Use new surface of towel with each wipe.

• AVOID TOUCHING OR WIPING A/R COATED OR METAL MIRROR SURFACES
• AVOID HANDLING EXPOSED COATINGS WITH BARE FINGERS

Orientation Instructions

Proper orientation of the filter is necessary in order to minimise autofluorescence and maximise performance. There is a caret (arrow) located on the edge of each filter in order to aid orientation. Excitation (x) filters should be positioned with the arrow pointing toward the specimen, toward the inside of the cube, and away from the light source. Emission (m) filters should be placed with the arrow pointing toward the specimen, toward the inside of the cube, and away from the detector/eye. Dichroic mirrors should be mounted with the coated surface toward the light source, excitation filters, and the specimen. The dichroics either have an arrow on the side pointing to the coated side, or they are beveled on the coated side. The beveled side is the smaller surface.