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Diagonals & Accessories

19 Items
Apertura 1.25" - 2" Focus Adapter

Apertura 1.25" - 2" Focus Adapter - A-FAD

SKU: APT-A-FAD
  • This adapter allows to to attach 1.25" accessories to 2" diagonal, focusers, and other 2" barrel accessories.

  • The compression ring included with this adapter firmly grips eyepieces and other 1.25" accessories.

  • Apertura has designed this adapter to be threaded to accept 2" (M48) filters.

  • The 1.25" to 2" adapter is black in color.
$22.95
William Optics SCT Adapter for Standard 2" Diagonal Gold

William Optics SCT Adapter for Standard 2" Diagonal - Gold - D-SCT-TA

SKU: WYO-D-SCT-TA-G
  • This adapter coverts the 2" push-in diagonal into an SCT diagonal.

  • All you have to do is replace the push-in nosepiece with this adapter.

  • WO has designed the adapter to have standard SCT female thread (2" & 24 TPI).

  • This SCT Adapter is anodized gold.
$39.00

High Point Self-Centering 2" to 1.25" Adapter - SCAD

SKU: HPS-SCAD
  • This adapter allows users to use 1.25" accessories in 2" openings.

  • The included helical compression ring holds accessories in place and keeps them centered.

  • High Point has added threads so the adapter can accept 2" filters.

  • Rotating the knurled top ring will lock and unlock accessories into place.
$24.95
Apertura 2" to 1.25" Self-Centering Adapter

Apertura Self-Centering 2" to 1.25" Adapter - A-SCAD

SKU: APT-A-SCAD
  • This adapter allows the use 1.25" accessories in 2" openings

  • Includes a helical compression ring to hold accessories in place and keep them centered

  • Threads enable this adapter to accept 2" filters

  • Rotating the knurled top ring will lock and unlock accessories
$24.95
$45.00

William Optics 1.25" RotoLock Adapter - Gold - F-ROTO-A2-125GDII

SKU: WYO-F-ROTO-A2-125GDII
  • This Rotolock adapter locks into the 2” opening of a WO Rotolock diagonal or focuser.
  • This is a steppingstone to attaching 1.25” barreled accessories.
  • Rotating the adapter ring will lock and unlock the inserted accessory into place.
  • Using this adapter will ensure that your accessory is centered.
$45.00
$45.00

Baader Planetarium 2" to 1.25" Reducer with T2 Threads - T2-15

SKU: BAD-T2-15
  • This Baader Planetarium reducer is compatible with all 2" Focusers.

  • Using this reducer allows users to use 1.25" eyepieces and accessories in a 2" focuser.

  • The reducer has a 3-point attachment system and is vibration free.

  • Baader has designed this reducer with 48 mm filter threads and an internal T-2 thread.
$49.00
William Optics RotoLock Eyepiece Adapter & Visual Back for 2 WO Diagonals

William Optics RotoLock Upgrade for WO 2" Diagonals - D-ROTO-A2

SKU: WYO-D-ROTO-A2
  • This Rotolock upgrade uses a flange to connect to WO 2" Diagonals.

  • Rotating the ring with lock and unlock the accessories in place.

  • No thumbscrews are used, so users do not have to worry about marring.

  • William Optics' Rotolock upgrade comes with a plastic protective dust cover.
$89.00

Stellarvue 2" to 1.25" Adapter with Filter Threads - FA002

SKU: STV-FA002
  • This Stellarvue adapter allow you to use 1.25” accessories in 2” openings.
  • The adapter is threaded for2” filters.
  • Stellarvue has included a compression ring which is ensure that the accessories stay safely in place.
  • This adapter does not need thumbscrews to hold the accessory in place.
$29.00
Baader Clicklock 2" to 1.25" Reducer Adapter

Baader Clicklock 2" to 1.25" Reducer - T2-15B

SKU: BAD-T2-15B
  • The Clicklock reducer from Baader holds 1.25” eyepieces.

  • A 20-degree twist of the knurled outer ring will lock and unlock the eyepieces in place.

  • A Clamp Lever is included to indicate clamp position.

  • The reducer is made from hardened bronze.
$89.00

William Optics Nosepiece for 2" Diagonal - WD-DIG2A

SKU: WYO-WD-DIG2A
  • This nosepiece converts a standard 2" SCT into a "push in" 2" diagonal.

  • To use this tool, replace the SCT adapter with the nosepiece.

  • Please note that this WO nosepiece will not work with 1.25" diagonals or 2" diagonals that have a built-in SCT mounting ring.

  • This is a great way to change your SCT diagonal to a "refractor type" diagonal.
$30.00
Takahashi Short 2" Visual Adapter

Takahashi 2" Visual Adapter - TKP27110S

SKU: TAK-TKP27110S
  • One side of the Visual Adapter threads onto the 8L Coupling from Takahashi.

  • The other side of the adapter accepts a variety of adapter and accessories.

  • This adapter is compatible with Takahashi's Sky 90.

  • It can be used with the FSQ-85, and FSQ-106EDX when certain accessories are used in conjunction.
$177.00
William Optics SCT RotoLock Adapter & Visual Back - 1.25"

William Optics 1.25" SCT RotoLock Adapter & Visual Back - F-ROTO-A2-125-SCT-TA

SKU: WYO-F-ROTO-A2-125-SCT-TA
  • One side of this adapter has an SCT thread and the other has a standard 1.25" Rotolock visual back.

  • Simply rotating the adapter will unlock and lock the inserted accessory into place.

  • The design of the adapter will firmly hold and center the accessory.

  • William Optics has utilized internal ball bearings and detents in this design.
$79.00
Takahashi 1.25" Eyepiece Holder

Takahashi 1.25" Compression Ring Ocular Adapter - TKP00101

SKU: TAK-TKP00101
  • The 1.25" Ocular Adapter is for 1.25" eyepieces and diagonals.

  • Takahashi has designed the adapter a two-point compression ring and chrome set-screws.

  • One side will thread into the 2" opening of the Coupling S Adapter from Takahashi.

  • The provided 1.25" sleeve will accept a 1.25" diagonal or eyepiece.
$89.00
Takahashi Coupling S - TKP00103

Takahashi Coupling S for Visual - TKP00103

SKU: TAK-TKP00103
  • On the telescope side, this adapter will connect to TKP86005 Visual Adapter or the 50.8 mm Sleeve from Takahashi.

  • One the other side, the Coupling S will connect to the 1.25" Ocular Adapter, which will then accept a 1.25" diagonal or eyepiece.

  • Takahashi's TCE0100 Collimating Scope will thread onto this adapter, which then connects to the focuser drawtube.

  • Using this adapter with the collimating scope will let you use the scope with Tak refractors that have a focal length of at least 1000 mm.
$52.00
Takahashi 50.8mm Sleeve - TKP00113

Takahashi 2" Sleeve to 1.25" Adapter - TKP00113

SKU: TAK-TKP00113
  • This sleeve adapter connects to the Coupling S on the eyepiece side.

  • On the telescope side, the sleeve adapter connects to the 2" Eyepiece Holder or the 50.8 mm Extension Tube.

  • This part serves as an alternative for the TCN0055 adapter.

  • With this sleeve you can connect the 1.25" Ocular Adapter, view through a 1.25" eyepiece, or insert a 1.25" diagonal.
$47.00
Takahashi 2" Ocular Adapter TKP27110

Takahashi 2" Eyepiece Adapter - TKP27110

SKU: TAK-TKP27110
  • This adapter threads directly to 2.7" focuser and will then accept a variety of accessories.

  • When looking at a system chart, this adapter is #70.

  • The adapter is black in color.

  • Takahashi has made this adapter for the Takahashi FS-102, FS-128, FS-152, FSQ-106, TOA-130N, and 130F series telescopes.
$177.00
Baader Planetarium 2" to 1.25" Pushfix T2 Thread Reducer

Baader Planetarium 2" to 1.25" Pushfix T-2 Thread Reducer - T2-15A

SKU: BAD-T2-15A
  • This thread reducer only has 1 mm optical path length.

  • The Pushfix reducer has three methods of attaching 1.25" accessories.

  • Baader has designed this reducer to work best with Newtonian Focusers.

  • With Countersunk Delrin grub screws, this reducer enables correct pressure.
$43.00

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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