On Sale Optolong UHC Filter - 1.25-inch
The Optolong UHC (Ultra High Contrast) broadband filter is designed to improve the visibility of deep sky objects such as emissin nebulae and supernova remnants. It rejects the typical wavelength associated to artificial light and it is highly transparent in teh main emission nebula lines: OIII, H-Beta, NII, H-alpha and SII.
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- Blocks artificial light from mercury vaopour lamps, both high and low pressure sodium vapour lights and the unwated natural light caused by neutral oxygen emission in our atmosphere
- Maximum transmission of the main nebula emission lines: OIII, H-beta, NII, H-alpha as well as SII
- Two Transmission Bands
- Can be used for visual observations as well as astrophotography
- Ideal for sub-rural areas with moderate light pollution
- Ultra-thin filter cell to maximise the compatibility with most filter wheels
- Multi-layers anti-reflection coating
For astronomy cameras, it needs to be used in combination with an IR/UV cut filter. Alternatively it can be used with the CLS-CCD filter that cuts off the infared and ultraviolet wavelengths. In DSLR the IR/UV filter is embedded in teh camera so the standard CLS filter is sufficient.
Light pollution filters do not eliminate the effects of light pollution or increase the object's brightness. It does increase the contrast between nebulae and night sky.
| Passing Band | Dual Band H-Alpha and OIII |
| Glass Thickness | 2.0mm (1.25" & 2" filters); 1mm (clip series) |
| Optical Flatness | 1/4 (wavefront) |
| Band-pass transmission | 90% across major nebulae bandpass |
| Coating | Fully multi-coated |
| Surface quality | 60/40 (in accordance with US military watch MIL-O-13830 |
| Parallelism | 30" |
| Glass type | Schott Monolithic Optical Substrate |
| Available sizes | 1.25", 2", clip on EOS-C |