1.Optolong UHC Introduction

The UHC (Ultra High Contrast) broadband filter is designed to improve the visibility of various deepsky objects. By selectively reducing the transmission of wavelengths of light pollutants, specifically those produced by artificial lightings including mercury vapor lamps, both high & low pressure sodium vapor lights /*C*and*C*/ the unwanted natural light caused by neutral oxygen emission in our atmosphere (i.e. skyglow). Together with the highly transparent in main nebula emission lines at OIII(496nm /*C*and*C*/ 500nm), H-beta (486nm), NII(654nm /*C*and*C*/ 658nm), H-alpha(656nm) as well as SII(672nm), the filter is suitable for enhancing the contrast /*C*and*C*/ details for both visual /*C*and*C*/ photograghic purpose at sub-rural area with heavy light pollution.

Main Use /*C*and*C*/ Performance

Suitable for color CCD cameras /*C*and*C*/ unmodified DSLRs.

UHC with narrower passband provides higher contrast than CLS. Thus it is more suitable for urban environment /*C*where*C*/ you suffer from severe light pollution.

UHC has a substantial red passband /*C*and*C*/ offer superb views for objects /*C*like*C*/ the Orion Nebula (M42).

Light pollution filter do /*C*not*C*/ eliminate the effects of light pollution /*C*or*C*/ increase the object’s brightness. In many cases, they increase the contrast between nebula /*C*and*C*/ night sky, /*C*not*C*/ brightening the nebula.

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

Technical Data

Sbustrate: optical glass
Tave>95%
Blocking range: 300-700nm
Blcoking depth: OD3, light pollution line blocking >99%
Surface quality: 60/40 (Refer to MIL-O-13830A, MIL-C-48497A)
Transmitted Wavefront RMS:  ¼ λ
 Parallelism: 30s

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