Optolong L-eXtreme Dual Bandpass Light Pollution Filter - 2"
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A. About Optolong's L-eXtreme Filter
The Optolong 2” L-eXtreme filter builds on the success of the renowned L-eNhance filter to deliver an even higher degree of contrast when imaging emission nebulae, planetary nebulae, and supernovae remnants. The L-eXtreme is two filters in one. It has a narrow 7nm passband centered on H-alpha at 656nm and a second 7nm passband centered on OIII near 501nm. The majority of nebulae have their strongest emission at these two wavelengths.
Unlike the L-eNhance filter, the L-eXtreme blocks the weaker H-beta emission line at 486nm to deliver more contrast in the fainter regions of nebulae, even in light-polluted sky. The narrower passbands of the L-eXtreme are especially important in blocking moonlight and broadband light pollution found in many urban and suburban centers.
The L-eXtreme is an ideal filter for use with DSLRs, one-shot color (OSC), and monochrome CCD and CMOS cameras, especially with fast optical systems. It’s an indispensable filter for urban and suburban astrophotographers and for everyone who likes to extend their imaging sessions into nights when the moon is bright.
B. Spectral Curve Transmission Characteristics
- FWHM: 7nm at O-III and 7nm at H-a
- Blocking range: 300 - 1000nm
- Light pollution line blocking depth: > 99%
C. Technical Specifications
- Both surfaces are fine optically polished, accurate to 1/4 wavelength or better, and parallel to within 30 seconds or arc.
- 1.85mm thick Schott B270 optical glass substrate material.
- Very high surface quality of 60/40 or better (US Military Spec MIL-O-13830).
D. Optical Coating Specifications
- Multi layer anti-reflection coated.
- Non-cementing optical substrate coating.
- Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL (central wavelength) so that there is no deviation due to temperature changes during use.
- Precise and homogeneous coatings ensure high values of desired passband and blocking of unwanted offband.
- Every single filter is tested and passed by Optolong before shipping to dealers.
E. Other
- 2" astronomy filter with standard M48x0.75 male filter thread (no female thread, so it cannot be stacked with other filters).
- Ultra-thin filter cell to minimize vignetting; clear optical aperture of 26mm.
- Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, and laser engraving.
- High quality protective plastic storage case.
WARNING: Optolong filters are not designed for direct solar observation. NEVER use these filters for observing the Sun, or permanent eye and equipment damage will result.
F. Sample Images and Comparisons
1. Compare L-eXtreme vs No Filter
- Object: M42
- Date: 15-16 March 2020
- Location: Hong Kong - Shatin (Light pollution level 7~8, City center, light pollution disaster area
- Camera: ZWO ASI183MC Pro
- Telescope: Sky-Watcher N130/650 f/5 with coma corrector
- Filter: Optolong L-eXtreme 2"
- Mount: iOptron CEM25EC
- Guide: 120mm mini guide scope, ZWO ASI120MM mini
- Copyright: © Vincent Cheng (Hong Kong)
2. IC1396 (Elephant Trunk Nebula) to Sh2-129 (Flying Bat Nebula)
The Optolong L-eXtreme is two 7nm filters in one: H-Alpha and OIII. The filter is a powerful tool for isolating these two important nebula lines against the effect of light pollution and moonlight, and it saves time by allowing capture of both bands in a single frame. Ideal for use with monochrome and color astronomy cameras and DSLRs.
- Location: La Jonquera, Girona, Spain
- Date: April 2020
- Camera: Canon 6D mod
- Telescope: WO SpaceCat 51
- Mount: Sky Watcher EQ6 Mount
- Guide: Guide camera QHY5
- Image Details:
- RGB 25 x 600" ISO 3200 - Optolong L-Pro
- H-Alpha & OIII 20 x900" ISO 3200 - Optolong L-eXtreme
- Flats, Darks & Bias
- Copyright: © Jose Jiminez
3. M8 (Lagoon Nebula) © Vincent Cheng (Hong Kong)
- Date: 30 April and May 1 2020
- Location: Lower Shing Mun Reservoir, Shatin, Hong Kong (Bortle scale: level 7~8)
- Camera: ZWO ASI183MC Pro (cooled at -10C)
- Telescope/Lens: SVBONY SV48 (500mm f5.5)
- Filter: Optolong L-eXtreme 2" Prototype
- Tracking Mount: Sky-Watcher AZ-GTi
- Controlled through ASIAIR PRO and SkySafari 6 plus
- Autoguide: 120mm mini guide scope, ZWO ASI120MM mini
- Total Exposure Time: 5mins X 21frames with Dark Frames, Processed with PI, PS CC
- Copyright: © Vincent Cheng (Hong Kong)
Useful Resources
Filter Cell Specifications
D = Filter Cell Diameter = 50.7 mm / 2.0 in
T = Total Filter Height = 7.1 mm / 0.28 in
C = Filter Cell Height (Excluding Male Thread) = 4.5 mm / 0.18 in
M = Male Thread Length = 2.6 mm / 0.1 in
F = USABLE Female Filter Thread Length = Not threaded, so you cannot stack additional filters
S = Glass Substrate Thickness = 1 mm / 0.04 in
CA = Clear Aperture = 45 mm / 1.77 in
Other Information
- Country of Manufacture: China
A. About Optolong's L-eXtreme Filter
The Optolong 2” L-eXtreme filter builds on the success of the renowned L-eNhance filter to deliver an even higher degree of contrast when imaging emission nebulae, planetary nebulae, and supernovae remnants. The L-eXtreme is two filters in one. It has a narrow 7nm passband centered on H-alpha at 656nm and a second 7nm passband centered on OIII near 501nm. The majority of nebulae have their strongest emission at these two wavelengths.
Unlike the L-eNhance filter, the L-eXtreme blocks the weaker H-beta emission line at 486nm to deliver more contrast in the fainter regions of nebulae, even in light-polluted sky. The narrower passbands of the L-eXtreme are especially important in blocking moonlight and broadband light pollution found in many urban and suburban centers.
The L-eXtreme is an ideal filter for use with DSLRs, one-shot color (OSC), and monochrome CCD and CMOS cameras, especially with fast optical systems. It’s an indispensable filter for urban and suburban astrophotographers and for everyone who likes to extend their imaging sessions into nights when the moon is bright.
B. Spectral Curve Transmission Characteristics
- FWHM: 7nm at O-III and 7nm at H-a
- Blocking range: 300 - 1000nm
- Light pollution line blocking depth: > 99%
C. Technical Specifications
- Both surfaces are fine optically polished, accurate to 1/4 wavelength or better, and parallel to within 30 seconds or arc.
- 1.85mm thick Schott B270 optical glass substrate material.
- Very high surface quality of 60/40 or better (US Military Spec MIL-O-13830).
D. Optical Coating Specifications
- Multi layer anti-reflection coated.
- Non-cementing optical substrate coating.
- Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL (central wavelength) so that there is no deviation due to temperature changes during use.
- Precise and homogeneous coatings ensure high values of desired passband and blocking of unwanted offband.
- Every single filter is tested and passed by Optolong before shipping to dealers.
E. Other
- 2" astronomy filter with standard M48x0.75 male filter thread (no female thread, so it cannot be stacked with other filters).
- Ultra-thin filter cell to minimize vignetting; clear optical aperture of 26mm.
- Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, and laser engraving.
- High quality protective plastic storage case.
WARNING: Optolong filters are not designed for direct solar observation. NEVER use these filters for observing the Sun, or permanent eye and equipment damage will result.
F. Sample Images and Comparisons
1. Compare L-eXtreme vs No Filter
- Object: M42
- Date: 15-16 March 2020
- Location: Hong Kong - Shatin (Light pollution level 7~8, City center, light pollution disaster area
- Camera: ZWO ASI183MC Pro
- Telescope: Sky-Watcher N130/650 f/5 with coma corrector
- Filter: Optolong L-eXtreme 2"
- Mount: iOptron CEM25EC
- Guide: 120mm mini guide scope, ZWO ASI120MM mini
- Copyright: © Vincent Cheng (Hong Kong)
2. IC1396 (Elephant Trunk Nebula) to Sh2-129 (Flying Bat Nebula)
The Optolong L-eXtreme is two 7nm filters in one: H-Alpha and OIII. The filter is a powerful tool for isolating these two important nebula lines against the effect of light pollution and moonlight, and it saves time by allowing capture of both bands in a single frame. Ideal for use with monochrome and color astronomy cameras and DSLRs.
- Location: La Jonquera, Girona, Spain
- Date: April 2020
- Camera: Canon 6D mod
- Telescope: WO SpaceCat 51
- Mount: Sky Watcher EQ6 Mount
- Guide: Guide camera QHY5
- Image Details:
- RGB 25 x 600" ISO 3200 - Optolong L-Pro
- H-Alpha & OIII 20 x900" ISO 3200 - Optolong L-eXtreme
- Flats, Darks & Bias
- Copyright: © Jose Jiminez
3. M8 (Lagoon Nebula) © Vincent Cheng (Hong Kong)
- Date: 30 April and May 1 2020
- Location: Lower Shing Mun Reservoir, Shatin, Hong Kong (Bortle scale: level 7~8)
- Camera: ZWO ASI183MC Pro (cooled at -10C)
- Telescope/Lens: SVBONY SV48 (500mm f5.5)
- Filter: Optolong L-eXtreme 2" Prototype
- Tracking Mount: Sky-Watcher AZ-GTi
- Controlled through ASIAIR PRO and SkySafari 6 plus
- Autoguide: 120mm mini guide scope, ZWO ASI120MM mini
- Total Exposure Time: 5mins X 21frames with Dark Frames, Processed with PI, PS CC
- Copyright: © Vincent Cheng (Hong Kong)
A. About Optolong's L-eXtreme Filter
The Optolong 2” L-eXtreme filter builds on the success of the renowned L-eNhance filter to deliver an even higher degree of contrast when imaging emission nebulae, planetary nebulae, and supernovae remnants. The L-eXtreme is two filters in one. It has a narrow 7nm passband centered on H-alpha at 656nm and a second 7nm passband centered on OIII near 501nm. The majority of nebulae have their strongest emission at these two wavelengths.
Unlike the L-eNhance filter, the L-eXtreme blocks the weaker H-beta emission line at 486nm to deliver more contrast in the fainter regions of nebulae, even in light-polluted sky. The narrower passbands of the L-eXtreme are especially important in blocking moonlight and broadband light pollution found in many urban and suburban centers.
The L-eXtreme is an ideal filter for use with DSLRs, one-shot color (OSC), and monochrome CCD and CMOS cameras, especially with fast optical systems. It’s an indispensable filter for urban and suburban astrophotographers and for everyone who likes to extend their imaging sessions into nights when the moon is bright.
B. Spectral Curve Transmission Characteristics
- FWHM: 7nm at O-III and 7nm at H-a
- Blocking range: 300 - 1000nm
- Light pollution line blocking depth: > 99%
C. Technical Specifications
- Both surfaces are fine optically polished, accurate to 1/4 wavelength or better, and parallel to within 30 seconds or arc.
- 1.85mm thick Schott B270 optical glass substrate material.
- Very high surface quality of 60/40 or better (US Military Spec MIL-O-13830).
D. Optical Coating Specifications
- Multi layer anti-reflection coated.
- Non-cementing optical substrate coating.
- Electron-beam gun evaporation with Ion-assisted deposition coating technology for durability and resistance to scratching, as well as stability on CWL (central wavelength) so that there is no deviation due to temperature changes during use.
- Precise and homogeneous coatings ensure high values of desired passband and blocking of unwanted offband.
- Every single filter is tested and passed by Optolong before shipping to dealers.
E. Other
- 2" astronomy filter with standard M48x0.75 male filter thread (no female thread, so it cannot be stacked with other filters).
- Ultra-thin filter cell to minimize vignetting; clear optical aperture of 26mm.
- Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, and laser engraving.
- High quality protective plastic storage case.
WARNING: Optolong filters are not designed for direct solar observation. NEVER use these filters for observing the Sun, or permanent eye and equipment damage will result.
F. Sample Images and Comparisons
1. Compare L-eXtreme vs No Filter
- Object: M42
- Date: 15-16 March 2020
- Location: Hong Kong - Shatin (Light pollution level 7~8, City center, light pollution disaster area
- Camera: ZWO ASI183MC Pro
- Telescope: Sky-Watcher N130/650 f/5 with coma corrector
- Filter: Optolong L-eXtreme 2"
- Mount: iOptron CEM25EC
- Guide: 120mm mini guide scope, ZWO ASI120MM mini
- Copyright: © Vincent Cheng (Hong Kong)
2. IC1396 (Elephant Trunk Nebula) to Sh2-129 (Flying Bat Nebula)
The Optolong L-eXtreme is two 7nm filters in one: H-Alpha and OIII. The filter is a powerful tool for isolating these two important nebula lines against the effect of light pollution and moonlight, and it saves time by allowing capture of both bands in a single frame. Ideal for use with monochrome and color astronomy cameras and DSLRs.
- Location: La Jonquera, Girona, Spain
- Date: April 2020
- Camera: Canon 6D mod
- Telescope: WO SpaceCat 51
- Mount: Sky Watcher EQ6 Mount
- Guide: Guide camera QHY5
- Image Details:
- RGB 25 x 600" ISO 3200 - Optolong L-Pro
- H-Alpha & OIII 20 x900" ISO 3200 - Optolong L-eXtreme
- Flats, Darks & Bias
- Copyright: © Jose Jiminez
3. M8 (Lagoon Nebula) © Vincent Cheng (Hong Kong)
- Date: 30 April and May 1 2020
- Location: Lower Shing Mun Reservoir, Shatin, Hong Kong (Bortle scale: level 7~8)
- Camera: ZWO ASI183MC Pro (cooled at -10C)
- Telescope/Lens: SVBONY SV48 (500mm f5.5)
- Filter: Optolong L-eXtreme 2" Prototype
- Tracking Mount: Sky-Watcher AZ-GTi
- Controlled through ASIAIR PRO and SkySafari 6 plus
- Autoguide: 120mm mini guide scope, ZWO ASI120MM mini
- Total Exposure Time: 5mins X 21frames with Dark Frames, Processed with PI, PS CC
- Copyright: © Vincent Cheng (Hong Kong)
Useful Resources
Filter Cell Specifications
D = Filter Cell Diameter = 50.7 mm / 2.0 in
T = Total Filter Height = 7.1 mm / 0.28 in
C = Filter Cell Height (Excluding Male Thread) = 4.5 mm / 0.18 in
M = Male Thread Length = 2.6 mm / 0.1 in
F = USABLE Female Filter Thread Length = Not threaded, so you cannot stack additional filters
S = Glass Substrate Thickness = 1 mm / 0.04 in
CA = Clear Aperture = 45 mm / 1.77 in
Other Information
- Country of Manufacture: China
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Optolong L-eXtreme Dual Bandpass Light Pollution Filter - 2"