Optolong 7nm (6.5nm SHO S-II, H-Alpha, O-III) 3 Piece Filter Set 31mm Round Unmounted

Latest Version - Higher contrast and coating enhancements.

Warning: As a critical safety reminder, this Optolong filter is not intended for solar observation. It should NEVER be used to observe the sun directly, as it can result in irreversible blindness. EDISLA does not assume responsibility for any incidents that may occur due to improper usage.

Narrowband filter set including SII (S) 6.5nm, Ha (H) 7nm and OIII (O) 6.5nm filters.

Narrowband imaging can be done with the moon up or in heavy light pollution so you can make the most of every clear night.

Data from each narrowband filter can be combined to create a final colour image, a common combination is HOO using H-alpha for the red and OIII for the green and blue channels. It can also be useful to use H-alpha data blended into an RGB data set to enhance the contrast and structural detail whilst maintaining a natural look.

Optolong 31mm Unmounted Filter Set with H-Alpha, SII, and OIII Filters:

The Optolong 31mm Unmounted Filter Set offers a versatile and cost-effective solution for astrophotographers seeking to enhance their deep-sky imaging capabilities. This set includes three high-performance filters: the 7nm Hydrogen-Alpha filter, the 6.5nm Sulfur-II filter, and the 6.5nm Oxygen-III filter. These filters are designed to fit color filter wheels that accept 31mm unmounted filters, providing flexibility in your astrophotography setup.

Key Features:

1. High-Quality Optics:

   • Each filter is constructed with Schott glass, renowned for its optical quality.
   • Multi-coating with ion-assisted deposition technology ensures scratch resistance and stability on the central wavelength (CWL).

2. Filter Set:

   • The set includes three essential filters for deep-sky astrophotography: H-Alpha, SII, and OIII.
   • These filters are carefully selected to capture specific wavelengths of light emitted by celestial objects, revealing fine details and structures.

3. Narrow Bandwidth Filters:

   • H-Alpha, SII, and OIII filters offer narrow bandwidths (7nm for H-Alpha and 6.5nm for SII and OIII).
   • These narrow bands isolate specific emission lines, enhancing contrast and minimizing the effects of light pollution.

4. Light Pollution Reduction:

   • The filters effectively reduce light pollution from both natural sources (skyglow) and artificial sources (sodium vapor and mercury vapor lights).
   • This reduction results in high-contrast images, allowing the H-alpha line to stand out prominently.

5. Infrared Blocking:

   • All filters designated as "CCD" block infrared wavelengths (700nm to 1100nm), eliminating the need for a separate IR-Cut filter.

6. Compatibility:

   • Designed for use in color filter wheels that accommodate 31mm unmounted filters.
   • Filters are unmarked and can be installed with either side facing up or down, providing ease of use. 

Optolong 7nm H-Alpha Filter - The Optolong H-Alpha 7nm is an extremely narrow emission-line filter that works by allowing a 7nm bandwidth of light, centered on the 656nm wavelength through, and blocking the transmission of contrast-killing light pollution wavelengths. Wavelengths that are responsible for natural light pollution, or skyglow, are drastically reduced, as is artificial light pollution caused by high and low-pressure sodium vapor and mercury vapor lights. The result is a high contrast image that reveals the H-alpha line in all its glory.

Optolong 6.5nm SII Filter - The Optolong Sulfur-II 6.5nm Extra-Narrowband Filter transmits a 6.5nm bandwidth of light that is centered at 672nm and drastically reduces other transmissions, including wavelengths of light that are responsible for light pollution (both artificial and natural). Like all Optolong filters that are designated as “CCD”, this SII filter also blocks infrared wavelengths from 700nm to 1100nm so you don't need a separate IR-Cut filter.

Optolong 6.5nm OIII Filter - The Optolong Oxygen III 6.5nm Extra-Narrowband Filter transmits a 6.5nm bandwidth of light that is centered at 500nm and drastically reduces other transmissions, including wavelengths of light that are responsible for light pollution (both artificial and natural). Like all Optolong filters that are designated as “CCD”, this OIII also blocks infrared wavelengths from 700nm to 1100nm so you don't need a separate IR-Cut filter.

The coating technology used in the Optolong filters is a crucial aspect of their performance and durability. Here's a breakdown of the coating technology employed:

1. Multi-layers Anti-reflection Coating:

   • This involves applying multiple layers of specialized coatings to the filter's surface. These coatings are designed to reduce reflections and increase the transmission of desired wavelengths.
   • Anti-reflection coatings help minimize glare and unwanted reflections, enhancing the filter's efficiency in passing specific spectral lines.

2. Non-Cementing Optical Substrate Coating:

   • This coating is applied to the optical substrate, which is the base material of the filter. Non-cementing coatings are designed to adhere well to the substrate without the need for additional adhesives or cement.
   • Such coatings contribute to the filter's durability and optical performance, as they are less prone to degradation over time.

3. Ion-assisted Deposition Coating Technology:

   • Ion-assisted deposition is a precise coating technique used to deposit thin films of materials onto the filter's surface. It involves the use of ions to enhance the deposition process.
   • This technology ensures the durability and scratch resistance of the filter coating. It also helps maintain the stability of the filter's Central Wavelength (CWL) under varying temperature conditions.

4. Planetary Rotation System:

   • The use of a planetary rotation system during the coating process ensures that the coatings are applied uniformly and precisely across the filter's surface.
   • This uniformity is essential for maintaining high transmission in the pass-band (desired wavelength range) and high optical density in the off-band (unwanted wavelengths).

In summary, Optolong employs advanced coating technology to enhance the performance and longevity of their filters. These coatings are designed to minimize reflections, resist scratching, and maintain stability in terms of central wavelength, ensuring that the filters deliver reliable and consistent results for astrophotography and astronomical observations.

The Optolong 31mm Unmounted Filter Set empowers astrophotographers to capture stunning images of deep-sky objects with enhanced contrast and clarity. Whether you're imaging nebulae, star clusters, or other celestial wonders, this filter set is a valuable addition to your astrophotography equipment.