Optec - #23A Light Red, 50mm diam x 2mm thick
Blocks blue and green light completely. Passes light longer than 600nm. This filter will block the sodium lines from low pressure sodium lights and effectively darkens the night sky from a variety of light sources including the moon. The H-alpha light from nebulae is passed completely. A good filter to use when the moon is up.
The Optec IFW Intelligent filter wheel (#17350) is the ideal compliment for holding this filter
Optec can supply a full range of filters for the IFW wheel. Filters are easily and safely mounted in the new IFW filter wheel by use of delrin plastic holding tabs and spacers. Filters from 1 to 5 mm in thickness can be accommodated with use of delrin ring spacers. Because the flexible tab and not the head of the screw holds the filter in place, it is impossible for the filter to be damaged by excess over tightening. An ample supple of tabs and spacers are supplied with each filter wheel.
Filter wheels for both 50mm diameter and 2-inch diameter are available. For special purposes, an 8 position wheel configured for 1-inch filters is offered.