The relentless spread of urbanization /*C*and*C*/ its associated light pollution have become a growing problem for all amateurs /*C*and*C*/ astro photographers. The current solutions to the problem can be expensive /*C*and*C*/ might include the purchase of a monochrome camera, several types of narrowband filters /*C*and*C*/ a filter wheel.

L-eNhance provides an economical /*C*and*C*/ practical solution for amateurs. It is a dual-band pass filter which has been designed for DSLR (digital SLR), color CMOS /*C*and*C*/ CCD cameras. The convenience /*C*and*C*/ cost effectiveness of this filter allows amateurs to image a rich selection of astronomical images, even in bright, heavily light-polluted areas.

Optolong's L-eNhance filter effectively isolates the H-Alpha, H-Beta, /*C*and*C*/ Oxygen III nebula emission lines /*C*and*C*/ achieves a maximum transmission of around 90%. The performance of this filter delivers images that superbly control the impact from light polluted skies.

B. Spectral Curve Transmission Characteristics

According to the characteristics of celestial body emission lines /*C*and*C*/ features of light pollution spectrum, Optolong specially designed /*C*and*C*/ optimized dual-band L-eNhance filter characteristics in order to retain the prominent RGB colors of nebulae while blocking out most light pollution.

• Peak transmission: > 90%
• Blocking range: 300 - 1000nm
• Light pollution line blocking depth: > 99%

C. Technical Specifications

• Both surfaces are fine optically polished, accurate to 1/4 wavelength /*C*or*C*/ better, /*C*and*C*/ parallel to within 30 seconds /*C*or*C*/ arc.
• 1.85mm thick Schott B270 optical glass substrate material.
• Very high surface quality of 60/40 /*C*or*C*/ 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 /*C*and*C*/ resistance to scratching, as well as stability on CWL (central wavelength) so that there is no deviation due to temperature changes during use.
• Precise /*C*and*C*/ homogeneous coatings ensure high values of desired passband /*C*and*C*/ blocking of unwanted offband.
• Every single filter is tested /*C*and*C*/ 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 45mm.
• Precision CNC-machined metal filter cell with sand blasted black anodized finish, anti-reflection treatment, /*C*and*C*/ laser engraving.
• High quality protective plastic storage case.

WARNING: Optolong filters are /*C*not*C*/ designed for direct solar observation. NEVER use these filters for observing the Sun, /*C*or*C*/ permanent eye /*C*and*C*/ equipment damage will result.