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Why we love the Optolong L1 Dual 2" Filter Combo Set L-QUAD + L-PARA (OPT-L1-DUAL-2)
Product Description
Introduction
L1 Dual 2" Filter Combo Set includes:1* L-Quad Enhance Filter & 1* L-Para Filter
- L-Quad Enhance Filter: Quad bandpass broadband filter, This filter provides better color balance while improving resistance of light pollution. It is suitable for a wide range of imaging targets, including continuous spectrum objects (RGB) such as nebulae, galaxies, and star clusters. This filter maximizes the preservation of RGB color balance in broadband spectrum targets like nebulae and galaxies, effectively improving contrast and detail to render subjects more vivid and three-dimensional.
- L-Para Filter: A dual narrowband 10nm filter, in systems with a focal ratio of F2 and above, the transmittance of nebula emission lines OIII and Ha exceed 85%, with excellent contrast and Anti-Halo characteristics. This filter suitable for all telescope systems, adaptable to fast optics (focal ratios of f/2 to f/4) as well as various standard/normal focal ratio telescopes. Ideal for capturing Ha & OIII signals in celestial objects, this filter enhances image contrast and reveals richer details in Ha & OIII emissions.
Filter Features
"Broadband + Narrowband" synergy engineered for precision and colour fidelity, achieves precise signal capture and color optimization for astrophotography.
- ►L-Quad Enhance Filter: Quad bandpass broadband filter captures the RGB signals of celestial targets
- ►L-Para : Dual narrowband 10nm filter selectively acquires Ha and OIII emission lines, revealing fine filamentary structures and the detailed morphology of ionised gas in deep-sky objects. After post-processing,photographers can effortlessly obtain fused images combining RGB with Ha & OIII data. This "Broadband-Narrowband Synergy" solution delivers more vibrant color rendition while accentuating subtle signal details, unlocking innovative approaches for astrophotography and enhancing the creative possibilities of color camera imaging. It pioneers new artistic dimensions, transforming the deep-sky photography process into a more technically engaging and visually rewarding experience.
Coating Technology
- Multi-layer 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
IC434: The Horsehead (and Flame) Nebula
The complex of which the nebulae IC434 the Large Hydrogen Wave in the centre, B33 the Horsehead Nebula and NGC2024 the Flame Nebula are part are located in the constellation Orion, in perspective proximity to the bright star Alnitak in the Orion Belt, about 1500 light years from us.

Specifications
| Filter | Optolong L-Para 2" | Optolong L-Quad Enhance 2" |
| Substrate | Optical Glass | Optical Glass |
| Thickness | 1.85mm | 1.85mm |
| FWHM | OIII: 10±0.5nm | Ha: 10±0.5nm | Quad Bandpass Filter |
| Transmittance | T>85% @ 500.7nm & 656.3nm | T>85% |
| Blocking Range | 300-1000nm | 300-1000nm |
| Blocking | OD ave>4 | OD2 - OD4 |
| Surface quality | 60/40 | 60/40 |
| Mount | The Optolong L-Para and L-Quad Enhance are both Standard 2" Mounted Filters | |


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Additional Articles, Videos, and Links
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