OPTOLONG L-SYNERGY narrow band dual filter in 2"

OPTOLONG L-SYNERGY 2" narrowband dual filter

The Optolong L-Synergy 2" is a 7 nm dual narrowband filter designed for astrophotography of nebulae with color cameras (DSLR, CMOS and CCD). It exclusively transmits the Oxygen III (500.7 nm) and Sulfur II (672.4 nm) emission lines, effectively blocking light pollution and increasing the contrast of the sky background.

Thanks to years of optical refinement, this filter significantly reduces halos around bright stars and maintains greater than 85% transmission, even in fast telescopes from f/3.3 and up.

Key benefits

• Ideal for color cameras: allows you to capture images in Hubble (SHO) palette without the need for a monochrome camera or a full set of three filters.

• Enhanced contrast and detail: by blocking light pollution, it brings out subtle structures in nebulae.

• Professional results with minimal investment: provides images comparable to monochrome SHO systems at a much lower cost.

• High transmission and halo reduction: cleaner and more natural images.

• Optimal compatibility: valid for fast telescopes from f/3.3.

Technical Specifications

• Size: 2" (M48×0.75).

• Substrate: optical glass

• Thickness: 1.85 mm.

• Bandpass (FWHM): OIII 7 nm, SII 7 nm.

• Transmittance: Tp > 85%.

• Blocking: 300-1050 nm.

• Surface flatness: λ/4.

• Surface quality: 60/40.

• Parallelism: 30".

Presentation

• Outer silver cardboard box.

• PP inner case with high density white EVA protection.

The Optolong L-Synergy is the perfect tool for those who want to go further in astrophotography of nebulae from urban or suburban skies, achieving images with a level of detail and color comparable to much more complex and expensive equipment.

why do we make an L-Synergy filter?

The fundamental innovation of L-Synergy filters lies not in a single functional breakthrough, but in the precise combination of traditional dual narrowband (Ha and OIII) technology, specifically tailored for color camera users. By adopting a dual-filter configuration of "Ha & OIII + SII & OIII", it overcomes the inherent limitations of color cameras in narrowband astrophotography. With L-Synergy, users can obtain Hubble Palette-style deep sky images comparable to those captured by monochrome SHO systems (SII/Ha/OIII), without the need to switch to a monochrome camera or purchase additional SHO filters.

This solution delivers high-quality results with minimal investment, making professional-grade narrowband imaging accessible to everyone.

1. Optolong L-Synergy

Optolong L-Synergy is a 7 nm dual narrowband filter compatible with DSLR cameras, color CMOS sensors and CCD cameras, compatible with telescope systems with a focal ratio of F3.3 or higher (slower systems). Its main advantage lies in enabling astrophotography enthusiasts to capture exceptionally detailed emission nebulae even in light-polluted environments.

After years of technical refinement, it has been optimized to minimize halos from bright stars while isolating all emission lines except SII and OIII, achieving maximum effective transmission.

Key features:

The advantage of Optolong L-Synergy lies in its selective transmission of only the OIII (500.7 nm) and SII (672.4 nm) nebula emission lines, blocking all other light pollution emission lines. This ensures that only oxygen and sulfur element signals are captured during imaging, resulting in a darker sky background and significantly improved contrast and signal-to-noise ratio (SNR) between nebulae.

Even in areas with heavy light pollution, this filter selectively transmits nebula emission lines while filtering out light pollution, ultimately eliminating its impact on astrophotography.

2. Optical design

By analyzing the spectral characteristics of both celestial emission lines and light pollution, L-Synergy selectively preserves SII and OIII nebula colors while filtering out most of the light pollution. Specifically designed and optically optimized, L-Synergy maintains consistently high transmission in both the SII and OIII bands. This ensures that users can accurately capture target nebula emissions, delivering optimal results in astrophotography.

3. Coating technology

- Multi-layer anti-reflective coating

- Uncemented optical substrate coating

- The filter Optolong adopts precision coating based on ion-assisted deposition technology for durability and scratch resistance, as well as center wavelength stability (CWL) without deviation caused by temperature changes.

- The planetary rotation system offers precision and homogeneity in coatings, ensuring high value in passband transmission and out-of-band optical density.

6. L-Synergy filter performance

I. WR134 in the Swan constellation © Gianni Lacroce

Test with the new Optolong L-Synergy filter, a 7 nm S2 O3 dual-band filter, and I have to say I really liked it.
I chose to shoot WR134 in the constellation of the Swan.
Having shot in monochrome, which normally results in a significant amount of signal with an H-alpha filter, the O3 is there, but sometimes I have to integrate a lot to make it stand out; the S2 doesn't show up at all. So I thought, "There won't be that much signal; to make a decent photo I'll have to integrate a lot," and so I took 200 5-minute shots.

Once the photo was processed, I discovered that it came out of the WBPP with no gradients or halos, but mostly bicolor, i.e., full of S2 and lots and lots of O3, and I think this is wonderful. I didn't have to do anything else in the processing except stretch the image, balance contrast, highlights and tones to customize it a bit, but in the end it was already like that in the raw file.

This filter greatly simplifies post production.
I will also show the starless Nebula to help understand the signal and the O3 it produces.
More shots with this new filter will follow soon.

EQUIPMENT
Imaging Telescope: Newton Tecnosky Carbon 200
Imaging Camera: ZWO ASI 2600 Duo
Mount: ZWO AM5
Filters Optolong L-Synergy

PHOTOS
Temperature 0 with dark, flat and darkflat
200 x 300s

PROCESSING
PixInsight
Photoshop

OPTOLONG L-SYNERGY narrow band dual filter in 2"