As many celestial objects; such as nebulae; radiate at other wavelengths; a considerable increase in contrast can be achieved by this; The background sky appears darker and all at once; faint details become visible
2 inch filter thread; each Alstar Ultra High Contrast Filter is individually inspected and proudly inscribed with the percentage of light transmittance of the O III and H beta emission lines
Can be used at both light polluted and dark sky sites; Blocks the light from mercury and sodium vapour lamps
The four-lens design with multi-coated surfaces eliminates most of the chromatic aberrations that show up with Barlow lenses having fewer components; A Barlow lens can therefore be a great supplement to your eyepiece collection
The Alstar Barlow lens provides 2.5 times greater magnification; allowing you to observe objects at a significantly closer apparent distance