DayStar Energy Rejection Filters reduce the heat load on your filter assembly by absorbing or reflecting UV and/or I light and transmitting light in the desired visual spectrum. These filters are sometimes Red or Yellow glass, or dielectric IR and UV, but pass light in the desired visual spectrum. The ERF can also serve as an aperture mask to accomplish a straight angle of incidence for light entering the filter.

DayStar filter assemblies operate best at f/30 and slower. Creating f/30 configuration can be done easily with the proper ERF and/or barlow.

In order to find the right ERF for your system, measure (with a ruler) the outside (largest) diameter of your telescope's dew shield at the very front of the telescope and size up to the nearest available ERF diameter (ie. for SkyWatcher Esprit 80 ED, the dew shield measures 125mm so you will need the 100 mm ERF for dew shields Ø 150 mm).

Variants

80 mm ERF for dew shields Ø 120 mm	DS-E-120N80
100 mm ERF for dew shields Ø 150 mm	DS-E-150N100
130 mm ERF for dew shields Ø 180 mm	DS-E-180N130
150 mm ERF for dew shields Ø 220 mm	DS-E-220N150

Dew shield diameters

SkyWatcher Evostar 80 ED	115 mm
SkyWatcher Evostar 100 ED	115 mm
SkyWatcher Evostar 120 ED	140 mm
SkyWatcher Esprit 80 ED	125 mm
SkyWatcher Esprit 100 ED	150 mm
SkyWatcher Esprit 120 ED	165 mm
SkyWatcher Esprit 150 ED	202 mm
Sharpstar 61EDPH-II	92 mm
Sharpstar 76EDPH	100 mm
Sharpstar 94EDPH	122 mm
Sharpstar 100Q-II	134 mm
Sharpstar 121SDQ	160 mm
Sharpstar AL-140PH	179 mm
Askar FRA400	100 mm
Askar FRA600	148 mm
Explore Scientific ES-ED80	127 mm
Explore Scientific ES-ED102	153 mm
Explore Scientific ES-ED127	175 mm
Explore Scientific FCD100 102	145.5 mm
William Optics FLT 132	168 mm

ENERGY REJECTION FILTERS

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