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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. 

Reflector Telescope Configurations:
Click here for full list of reflectors
Telescope on which
DayStar will mount
Off-axis Reduced aperture:
ERF aperture and cost
No barlow needed
Full aperture, On-axis
ERF aperture/ barlow needed / ERF Price
Meade ETX 90 Mak
32mm aperture - $200
90mm aperture / 2X barlow / $450
Meade ETX 105 Mak
35mm aperture - $200 
105mm aperture / 2X barlow / $505
Meade ETX 5" Mak
38mm aperture - $250
127mm aperture / 2X barlow / $750
Meade ETX 7" Mak
50mm aperture - $300
165mm aperture / 2X barlow / $1000
Meade LX 200 8"
63mm aperture - $400
-
Meade LX 200 10"
80mm aperture - $400
-
Meade LX 200 12"
100mm aperture - $505
-
Meade LX 200 14"
114mm aperture - $550
-
Meade LX 200 16"
125 mm aperture - $750
-
Celestron NexStar 4"
35mm aperture - $200
105mm aperture / 2.5X barlow / $505
Celestron C5 NexStar 5"
38mm aperture - $250
127mm apeture / 2X or 2.5X barlow/ $750
Celestron NexStar 6"
50mm aperture - $300
150mm aperture / 2.5X barlow / $900
Celestron C8 / NexStar 8"
63mm aperture - $350
-
Celestron C9.25
80mm aperture - $400
-
Celestron C11
90mm aperture - $450
-
Celestron C14
114mm aperture - $550
-
Mewlon 180
63mm aperture - $350
165mm aperture / 2.5X barlow / $1000
Mewlon 250
90mm aperture - $450
-
Questar 3.5"
32mm aperture - $200
90mm aperture / 2X barlow / $450
Refractor (On AXIS) Telescope Configurations:
Click here for full list of refractors
Telescope on which
DayStar will mount
Reduced aperture:
ERF aperture and price
No barlow needed
Full aperture
aperture / barlow needed / ERF Price
AP 105mm F/6 Traveler 25mm aperture - $150 90mm aperture / 4X barlow / $440
AP 130mm F/8 Starfire 35mm aperture - $225 130mm aperture / 4X barlow / $750
AP 140mm F/7.5 Starfire 35mm aperture - $225 140mm aperture / 4X barlow / $850
AP 160mm F/7.5 Starfire 40mm aperture - $250 160mm aperture / 4X barlow / $1000
Televue TV102 F/8.6 32mm aperture - $200 102mm aperture / 3X - 4X barlow / $505
Meade 4" F/9 32mm aperture - $200  100mm aperture / 3X barlow / $505
Meade LXD75 5" F/9 38mm aperture - $240  127mm aperture / 3X barlow / $750
Meade LXD75 6" F/8 40mm aperture - $260  150mm aperture / 4X barlow / $900
Celestron SLT 80mm F/11.25 80mm aperture / 2.5X barlow / $400
Celestron Advanced 80mm F/7.5 80mm aperture / 4X barlow / $400
Celestron 90mm F/12.3 38mm aperture - $250 90mm aperture / 2.5X barlow / $450
Celestron Advanced 100mm F/9 32mm aperture - $200 102mm aperture / 3X barlow / $505
Celestron Omni 120mm F/12.9 50mm aperture - $300 120mm apeture / 2.5X barlow / $750
Celestron Advanced 150mm F/8 40mm aperture - $250 150mm aperture / 4X barlow / $900
Williams Optics FS 102 F/8 32mm aperture - $200 100mm aperture / 4X barlow / $505
Williams Optics TOA 130 F/7.7 32mm aperture - $200 130mm aperture / 4X barlow / $750
Williams Optics ZenithStar 80 F 6.8 75mm aperture / 4X barlow / $375
Williams Optics Megres 90 F 6.9 80mm aperture / 4X barlow / $400
FLT 110 F/7 100mm aperture / 4X barlow / $505
FLT 132 F/7 32mm aperture - $200  127mm aperture / 4X barlow / $750
Vixen ED81 F/7.7 80mm aperture / 4X barlow / $400
Borg 101 F/6.3 32mm aperture - $200 90mm aperture / 4X barlow / $450
Borg 125 F/6.4 100mm aperture / 4X barlow / $505
TMB 130mm F/7 32mm aperture - $200 125mm aperture / 4X barlow / $750
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.  See formula below for details.
DESIRED ERF
APERTURE IN MM =
(APERTURE in mm) x FOCAL RATIO x BARLOW POWER
30

DayStar Filters LLC™ 149 Northwest OO Highway   Warrensburg, MO 64093 - USA
Telephone: 660-747-2100 • service@daystarfilters.com • FAX: 1-866-791-0448

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