Energy Rejection Filters

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 as listed below. If you don’t see your telescope, visit our full list of reflectors or refractors or contact us for your exact model. Higher resolution, larger aperture configurations use a barlow.

In order to compute the proper aperture reduction mask, divide your telescope EFL or Focal Length by 30.  To compute the proper aperture using a barlow, use the adjusted EFL which includes multiplication by your barlow.

ApplicationSKU #Specification
Energy Rejection-RefractorDSIUV2Daystar 2″ UV/IR Filter – For refractor
Energy Rejection-RefractorE-100N7575mm ERF Glass, Cell & 100mm ID Cap – For refractor
Energy Rejection-RefractorE-110N7575mm ERF Glass, Cell & 110mm ID Cap – For refractor
Energy Rejection-RefractorE-110N8080mm ERF Glass, Cell & 110mm ID Cap – For refractor
Energy Rejection-RefractorE-120N8080mm ERF Glass, Cell & 120mm ID Cap – For refractor
Energy Rejection-RefractorE-120N100100mm ERF Glass, Cell & 120mm ID Cap – For refractor
Energy Rejection-RefractorE-130N100100mm ERF Glass, Cell & 130mm ID Cap – For refractor
Energy Rejection-RefractorE-140N100100mm ERF Glass, Cell & 140mm ID Cap – For refractor
Energy Rejection-RefractorE-150N100100mm ERF Glass, Cell & 150mm ID Cap – For refractor
Energy Rejection-RefractorE-150N130130mm ERF Glass, Cell & 150mm ID Cap – For refractor
Energy Rejection-RefractorE-160N130130mm ERF Glass, Cell & 160mm ID Cap – For refractor
Energy Rejection-RefractorE-170N130130mm ERF Glass, Cell & 170mm ID Cap – For refractor
Energy Rejection-RefractorE-170N140140mm ERF Glass, Cell & 170mm ID Cap – For refractor
Energy Rejection-RefractorE-180N130130mm ERF Glass, Cell 180mm ID Cap – For refractor
Energy Rejection-RefractorE-180N150150mm ERF Glass, Cell & 180mm ID Cap – For refractor
Energy Rejection-RefractorE-190N130130mm ERF Glass, Cell & 190mm ID Cap – For refractor
Energy Rejection-RefractorE-190N150150mm ERF Glass, Cell & 190mm ID Cap – For refractor
Energy Rejection-RefractorE-200N140140mm ERF Glass, Cell & 200mm ID Cap – For refractor
Energy Rejection-RefractorE-200N150150mm ERF Glass, Cell & 200mm ID Cap – For refractor
Energy Rejection-RefractorE-210N150150mm ERF Glass, Cell & 210mm ID Cap – For refractor
Energy Rejection-RefractorE-220N150150mm ERF Glass, Cell & 220mm ID Cap – For refractor
Energy Rejection – SCT 8″E-244F6363mm ERF Glass, Cell & 244mm ID Cap – off-axis for SCT
Energy Rejection – SCT 9.25″E-281F8080mm ERF Glass, Cell & 281mm ID Cap – off-axis for SCT
Energy Rejection – SCT 10″E-311F8080mm ERF Glass, Cell & 311mm ID Cap – off-axis for SCT
Energy Rejection – SCT 11″E-325F9090mm ERF Glass, Cell & 311mm ID Cap – off-axis for SCT
Energy Rejection – SCT 12″E-356F100100mm ERF Glass, Cell & 356mm ID Cap – off-axis for SCT
Energy Rejection – SCT 14″E-410F115115mm ERF Glass, Cell & 410mm ID Cap – off-axis for SCT
Energy Rejection – SCT 16″E-460F125125mm ERF Glass, Cell & 460mm ID Cap – off-axis for SCT