Our high-quality infrared and ultraviolet blocking filter is designed for use with modern web cam and CCD imaging cameras. If you use a web cam with almost any telescope except a well-corrected Newtonian, you are likely to encounter halos around stars and a problem often referred to as "fuzzy focus". This happens because any telescope that employs any form of lens in the light path is unable to bring the whole light spectrum to a single well-defined focus. The UV and IR parts of the spectrum will be brought to different focus points to the rest of the spectrum, hence the loss of resolution and halo effects. |