|Orion V Block Filter 2" Ref: 05597|
With refractors, its normal to see some purple fringing or halos around bright objects such as the planets, Moon, and bright stars. Such false color, or chromatic aberration, results from the inability of a standard two-element (achromatic) lens assembly to focus all wavelengths of light to a single point. The effect is particularly pronounced at high powers.
But if you are the type that thinks halos look better on angels than on astronomical objects, then this violet-reduction filter is for you. It effectively removes the distracting color halos from around bright objects, greatly improving image sharpness, color, contrast, and resolution.
The Orion V-Block works amazingly well with achromatic refractors of any aperture or focal length. Its sophisticated coatings selectively block wavelengths in the violet and blue (<450nm) end of the visible spectrum, while allowing up to 95% transmission of the other wavelengths.
And you will find that you can push the magnification higher with the filter than without it because of the improved image definition. Objects also snap into focus more readily now that the fuzzy blue-violet fringe is attenuated.
The V-Block is a glass filter encased in an anodized aluminum cell. It threads into eyepieces, diagonals, and barlow lenses threaded to accept 2" filters. Effective for visual use as well as CCD or film imaging. Comes with protective plastic case.