What are LPR filters?
• Broad-band Light Pollution Reduction filters are intended to block light emitted by street lights (usually high- and low-pressure sodium and mercury vapour). They also block starlight in the same frequencies. Therefore they offer little or no significant improvement on objects that are comprised of stars (galaxies, clusters, etc.) or those that reflect starlight (reflection nebulae), but can improve emission nebulae. • Narrow-band filters are very good on planetary and emission nebulae. • Line filters (the common ones are O-III and H-beta) are excellent on most emission nebulae, but reduce the visibility of of objects whose light is starlight or reflected starlight.For more information on applicability of LPR filters, see Filter Performance Comparisons for Some Common Nebulae. For a graph of filter transmission characteristics, see http://home.attbi.com/~mcculloch-brown/astro/Compare.
• Broad-band Light Pollution Reduction filters are intended to block light emitted by street lights (usually high- and low-pressure sodium and mercury vapour). They also block starlight in the same frequencies. Therefore they offer little or no significant improvement on objects that are comprised of stars (galaxies, clusters, etc.) or those that reflect starlight (reflection nebulae), but can improve emission nebulae. • Narrow-band filters are very good on planetary and emission nebulae. • Line filters (the common ones are O-III and H-beta) are excellent on most emission nebulae, but reduce the visibility of of objects whose light is starlight or reflected starlight.For more information on applicability of LPR filters, see Filter Performance Comparisons for Some Common Nebulae.
