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  • Baader Planetarium Baader Planetarium Amici Star Diagonal 1.25" Correct Image - AMICI-DX1
    $319.00
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  • Baader Planetarium SCT Lock Ring for 2
    Baader Planetarium Baader Planetarium SCT Lockring for 2" Maxbright Diagonal - LRING
    $44.00
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  • Baader Planetarium 1.25
    Baader Planetarium Baader Planetarium T-2 Maxbright 1.25" Mirror Diagonal - MAX-1
    $299.00
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  • Baader Planetarium 2
    Baader Planetarium Baader Planetarium 2" Clicklock Mirror Diagonal - CLDIAG-2
    $309.00
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  • Celestron 2
    Celestron Celestron 2" Diagonal with XLT Coatings for Schmidt Cassegrain Telescopes - 93527
    $159.95 $139.95
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  • Celestron 45º Correct Image Prism Diagonal - 1.25
    Celestron Celestron 1.25" 45º Correct Image Prism Diagonal - 94112-A
    $41.95 $37.95
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  • Celestron 90º Prism Star Diagonal - 1.25
    Celestron Celestron 1.25" 90º Prism Star Diagonal - 94115-A
    $41.95 $37.95
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  • Explore Scientific 2
    Explore Scientific Explore Scientific 2" Dielectric Diagonal - DD02-00CF
    $139.99
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  • High Point High Point 1.25" Dielectric Mirror Diagonal - HPS-D1
    $69.95
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  • High Point High Point 2" Dielectric Mirror Diagonal - HPS-D2
    $109.95
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  • High Point High Point 2" Quartz Dielectric Diagonal - HPS-D2Q
    $129.95
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  • High Point High Point 2" SCT Quartz Dielectric Diagonal - D2QSCT
    $139.95
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  • High Point High Point 1.25" 45 Degree Prism Diagonal - HPS-P45
    $29.95
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  • Meade Meade 918A Diagonal Mirror - 1.25" - 07202
    $29.99 $26.95
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  • Meade 932 Erect Prism for ETX
    Meade Meade 1.25" Correcting Prism 45° Diagonal for ETX 90/105/125 - 07210
    $49.99 $39.95
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  • Meade Meade 1.25" Erect-Image 45° Diagonal Prism - 07217
    $39.99 $31.95
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  • Meade Meade 1.25" Correcting Prism 45° Diagonal for ETX-70 - 07220
    $49.99 $44.95
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  • Meade Meade 2" Diagonal with SCT Adapter - 07680
    $149.99
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  • Orion Orion 2" Dielectric Mirror Star Diagonal - 08727
    $139.99
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  • Orion Orion 1.25" Dielectric Mirror Star Diagonal - 08880
    $109.99 $84.99
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  • Stellarvue 1.25
    Stellarvue Stellarvue 1.25" Enhanced Dielectric Diagonal - D1030
    $99.00
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  • Stellarvue Stellarvue 1.25" 45° Erecting Prism - D1032
    $69.00
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  • Stellarvue Stellarvue 2" Correct Image 45° Erecting Prism - D1035
    $209.00 $199.00
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  • Tele Vue Tele Vue 1.25" 45 Degree Image Correcting Prism Diagonal - AMI-0011
    $64.95
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  • Tele Vue Tele Vue 1.25" 90 Degree Everbrite Mirror Star Diagonal - DPC-1250
    $179.95
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  • Tele Vue Tele Vue 1.25" 60 Degree Everbrite Mirror Diagonal - DPC-6012
    $234.95
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  • William Optics 1.25
    William Optics William Optics 1.25" Dielectric Diagonal W/ Carbon Fiber Plates - D-125D-C-DB
    $89.00
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  • William Optics 45º Erect Prism - 1.25
    William Optics William Optics 1.25" 45° Erect Prism - D-EP125
    $80.00
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  • Celestron Visual Back for Schmidt-Cassegrain Telescopes - 1.25
    Celestron Celestron 1.25" Visual Back for SCT Telescopes - 93653-A
    $36.95 $29.95
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  • High Point High Point SCT Dielectric Diagonal - 2" - HPS-D2SCT
    $114.95
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  • Baader Astro-Box #1
    Baader Planetarium Baader Planetarium Astro-Box #1 (M31) - BAB
    $11.00
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  • Baader Planetarium Baader Planetarium Nose Piece 1.25"/T2 - T2-14
    $35.00
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  • Baader T2-19 Adapter
    Baader Planetarium Baader Planetarium 2" Nosepiece - Fits Internal 2" SCT Threads - T2-19
    $42.00
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  • William Optics 2
    William Optics William Optics 2" Dura Bright Dielectric Mirror Diagonal with Thermometer - D-DIG2D-C-DB
    $139.00
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  • William Optics 2
    William Optics William Optics 2" Dura Bright Dielectric SCT Diagonal - D-DIG2D-C-DB-SCT
    $158.00
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  • William Optics William Optics Nosepiece for 2" Diagonal - WD-DIG2A
    $30.00
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  • Explore Scientific 3
    Explore Scientific Explore Scientific 3" Carbon Fiber Dielectric Diagonal - DD03-01CF
    $409.99
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  • Baader Planetarium T2 90º Prism Star Diagonal with 1.25
    Baader Planetarium Baader T-2 90º Prism Star Diagonal with 1.25" Nosepiece & Eyepiece Holder - PRISM-1
    $169.00
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  • Baader 2
    Baader Planetarium Baader Planetarium 2" Zeiss Prism Star Diagonal with BBHS Coatings & 2" ClickLock Eyepiece Clamp - PRISM-2Z
    $539.00
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  • Baader Planetarium T2 90º Star Diagonal Zeiss Prism
    Baader Planetarium Baader T2 90º Star Diagonal Housing - Zeiss Prism, 34mm Clear Aperture - T2-01B
    $272.00
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A star diagonal is a useful astronomy accessory because it allows viewers to look through their telescope perpendicular to the direction the telescope points or at a 45° angle. This makes diagonals handy for terrestrial observations as well. The people at High Point Scientific understand that the comfort and convenience of using a star diagonal is important to you, that is why we offer many different types of telescope diagonals for you to choose from. You will find the latest brands offering a variety of diagonals, including mirror, dielectric, and prism diagonals.


As the name suggests, mirror diagonals use a mirror to turn the telescope’s image at a 90° or 45° angle. This creates an image that is correctly oriented vertically but reversed horizontally. The mirror is typically made of silver or aluminum, both of which scratch easily. You will need to careful when cleaning and using your mirror diagonal. However, mirror diagonals are often very affordable which makes them a favorite among amateur astronomers.


Many astronomers prefer mirror diagonals but wish they were more durable. That’s why High Point Scientific also offers dielectric diagonals. Dielectric diagonals are mirror diagonals but include enhanced dielectric coatings for greater durability and reflectivity. These coatings make dielectric diagonals hard and sturdy so it is much more difficult to scratch or mar mirror surfaces.


Prism diagonals are often considered the most innovative design for a diagonal. They use a glass prism that often produces higher reflectivity than mirror or dielectric diagonals. This means that prism diagonals suffer minimal light loss to give you high contrast celestial views. Be sure to look for Amici prism diagonals on the High Point Scientific website, as these produce an upright image with a correct left-right view for low-powered eyepieces.

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