What is  L2 Dual-Combo Set?

L2 Dual-Combo Set includes two premium filters: one L-eXtreme and one L-Synergy.

L-eXtreme:The L-eXtreme is a dual-narrowband filter (OIII-7nm & Ha-7nm) designed to exclusively transmit the key nebula emission lines of OIII (500.7nm) and Hα (656.3nm). By effectively blocking all other light pollution emission lines, it ensures that only the signals from OIII and Hα elements are captured during imaging, achieving maximum effective transmission. With years of technological refinement, it significantly optimizes the performance in suppressing bright star halos.

L-Synergy：The L-Synergy is a dual-narrowband filter (OIII-7nm & SII-7nm) that guarantees high transmission for both the SII (672.4nm) and OIII (500.7nm) spectral lines, while offering exceptional out-of-band rejection for all other wavelengths. By effectively blocking all other light pollution emission lines, it ensures that only the signals from OIII and SII elements are captured during imaging, achieving maximum effective transmission. With years of technological refinement, it significantly optimizes the performance in suppressing bright star halos.

1.  Why is L2 Dual-Combo Set?

The L2 Dual-Combo Set is engineered to unleash the power of Hubble Palette imaging for color camera users, supporting telescope systems as fast as F3.3, and above ( slower system).

Tailored specifically for color camera astrophotographers, this set includes two premium filters: OIII & Hα (L-eXtreme),OIII & SII (L-Synergy).

This innovative combination breaks through the traditional limitations of narrowband imaging with color cameras. Without the need to switch to a monochrome camera or invest in an expensive SHO three-filter set, users can achieve stunning Hubble Palette images at a fraction of the cost and complexity.

The core appeal of this combination design lies in lowering barriers and expanding possibilities for colour camera users: it preserves the equipment advantages of colour cameras while enabling users to unlock “Hubble-like” creative capabilities at minimal cost through minimalist filter combination. Simultaneously, it offers greater flexibility for astrophotography.

Whether capturing nebular detail or reproducing deep-sky colours, this combination enables richer creative expression, truly unlocking the full potential of colour cameras in deep-sky photography.

2.Optical Design

Based on the characteristics of celestial emission lines and light pollution emission lines, the L2 Dual-Combo Set preserves the distinctive colours of nebulae in OIII, Hα, and SII while filtering out the vast majority of light pollution. Specifically designed and optically optimized, its transmission profile is as follows:

How to read the chart?

• The horizontal axis is the Wavelength in Nanometers(nm).
• The vertical axis is transmission in %.

3. Coating Technology

• Multi-layers anti-reflection coating
• Non-cementing optical substrate coating
• Optolong filter adopts precision coating based on Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL(central wavelength) no deviation affected by temperature change.
• Planetary rotation system offers precision and homogeneity of coatings ensuring high value on transmission of pass-band and Optical density of off-band.

Scope of Delivery:

• Optolong L2 Dual-Combo Set (L-eXtreme&L-Synergy)