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Diagonals & Accessories

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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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  • Baader Planetarium T2 90º Prism Diagonal Housing - 32 mm Clear Aperture
    Baader Planetarium Baader T2 90º Prism Diagonal Housing - 32mm Clear Aperture - T2-01C
    $129.00
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  • Baader Planetarium Baader T2 BBHS Sitall Mirror Diagonal - MAX1S
    $299.00
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    free shipping
  • Baader 1.25
    Baader Planetarium Baader 1.25" Maxbright Amici 45º Erecting Prism with Integrated 2X Glass Path Corrector - MAXAMICI
    $115.00 $92.00
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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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