The Optolong 3nm Narrowband filter sets includes the following items:

• Optolong H-alpha 3nm
• Optolong OIII 3nm
• Optolong SII 3nm

The NEW Optolong 3nm H-Alpha, Oxygen-III and Sulphur-II narrow-band filters boost the contrast of emission nebulae and supernova remnants for professional results, even under a bright sky affected by light pollution. This filter is used in combination with the OIII and SII filter to compose a narrowband colour image.

The 3nm band pass is only 1% of the entire visible spectrum, increasing the signal to noise ratio and delivering high contrast images and extremely dark backgrounds.

The high transmission and off-band blocking maximize contrast and minimise the halos around bright stars.

The filter cuts off the ultraviolet and infrared light so there is no need to use the IR-cut filter.

Every Optolong filter is marked with its unique serial number and individual passing band certificate. This test is rarely provided by any producer and it is a standard for high quality filters.