Optolong Moon & Skyglow Filter 2″

1.  Moon & Skyglow Introduction

Optolong Moon & Skyglow filter is designed to darken the background sky by blocking light transmission from skyglow 589nm and many street light emissions from artificial light. Its high efficiency preserves image brightness, reveals more details and increases contrast of moon, galaxies, nebulae and globular star clusters.

Main Use

Ideally it is quite versatile filter for visual observation and astrophotography on planetary nebula.

WARNING: The filters of Optolong are not designed for sun observation. DO NOT LOOK AT THE SUN WITH OPTOLONG FILTER. You would be BLIND if you fail to observe the warning.

2. Moon & Skyglow Spectrum and Characteristic
Sbustrate: B270
Thickness: 1.85mm
Tave:  T>90%
Blcoking depth: light pollution  line blocking >99%
Surface quality: 60/40
Transmitted Wavefront RMS: λ/4
 Parallelism: 30s

How to read the chart?

▲The horizontal axis is the Wavelength in Nanometers(nm).

▲The v