The Best Telescope Diagonals

Looking for the best Telescope Diagonals?

Discover now our comparison of the best Telescope Diagonals. It is never easy to choose from the wide range of offers. On the market, you will find an incalculable number of models, all at different prices. And as you will discover, the best Telescope Diagonals are not always the ones at the highest prices! Many criteria are used, and they make the richness and relevance of this comparison.
To help you make the best choice among the hundreds of products available, we have decided to offer you a comparison of the Telescope Diagonals in order to find the best quality/price ratio. In this ranking, you will find products listed according to their price, but also their characteristics and the opinions of other customers. Also discover our comparisons by categories. You won’t have to choose your products at random anymore.

No. 1

SVBONY SV188P Dielectric Mirror Star Diagonal, 90 Degree Mirror Diagonal, 99% Reflectivity Dielectric Coatings with Brass Compression Rings (1.25 inch)

Dielectric coatings; super flat mirror with dielectric coatings to reduce reflected light loss; provide an over 99% reflective surface; good for astronomical viewing
1.25 inches nosepiece fits 1.25 inches telescopes; accepts standard 1.25in filters; eyepieces; Barlow lenses and other accessories with a 1.25in insert barrel
90 degree viewing angle; diagonal reflects the telescope’s light path 90 degree to provide a more comfortable viewing angle; best for observing objects overhead
Correct upside down and left right reversed image; the view image is upright; but left and right reversed if use the 90 degrees to your telescope
Brass compression ring; Built in brass ring and thumbscrew accessories avoid eyepiece to rotate during adjustments; effortless fixes more firmly and will not scratch your eyepieces barrels

No. 2

$SVBONY SV221 90 Degree Diagonal Mirror, Telescope Diagonal 1.25 inches with Brass Compression Rings, Telescope Accessory for Refractor Telescope$

SVBONY SV221 90 Degree Diagonal Mirror, Telescope Diagonal 1.25 inches with Brass Compression Rings, Telescope Accessory for Refractor Telescope

Enhanced Aluminum Die; the SV221 diagonal mirror is designed with enhanced aluminum mold; which has higher light transmittance and clearer vision
1.25 inches diameter; the SV221 diagonal mirror has a diameter of 1.25 inches; which can be applied to a 1.25 inches telescope and a 1.25 inches eyepiece
With a brass pressure ring; the SV221 diagonal mirror has a brass pressure ring; which can prevent surface damage and scratch marks when the eyepiece is used with the SV221
Supports 1.25-inch filters features internal extinction treatment and supports the connection of 1.25-inch filters; Offering versatility for various observations
With filter thread; the SV221 diagonal mirror has M28.5x0.6mm filter thread; which supports the connection of 1.25 inches filter
90 degrees design; the SV221 diagonal mirror 90 degrees deflection angle design; you don't have to bend over when performing visual observation; and the observation experience is more comfortable
Internal extinction design; the SV221 diagonal mirror has internal extinction treatment; and the acquired image is clearer and brighter

SaleNo. 3

Celestron 93573 Dielectric Star Diagonal 2" with Twist Lock

Enjoy better views through your telescope with this premium diagonal featuring diffraction-limited optics and dielectric coatings
Provides a 90° viewing angle, perfect for more comfortable viewing through refractor and cass grain-type telescopes
58 layers of dielectric coatings provide an over 99% reflective surface, ensuring the maximum amount of light collected by the telescope reaches the eyepiece
Twist-lock keeps the eyepiece centered in the diagonal to provide better optical alignment
Includes a Stepdown adapter, so the diagonal accepts eyepieces, Barlow lenses, threaded filters, and other accessories in both 2” and 1. 25” sizes

No. 4

$SVBONY 1.25 inches 90 Degree Dielectric Mirror Diagonal Fully Metal for Refracting Telescope Eyepiece Lens for Astronomical Visual Astrophotography$

SVBONY 1.25 inches 90 Degree Dielectric Mirror Diagonal Fully Metal for Refracting Telescope Eyepiece Lens for Astronomical Visual Astrophotography

The 90% reflectivity flat mirror can reduce light loss and make the field of view clearer and sharper
Standard 1.25 inches diameter can be used with 1.25 inches telescope accessories such as eyepieces and barlow lens
90 degree viewing angle; provide a more comfortable observation angle to observe the stars above the head
Compatible with refractors and catadioptric telescopes; not suitable for reflector telescopes
Body material is full metal; With dust cover always keep your lens clear prolong life

No. 5

SVBONY 2 inches 90 Deg Dielectric Mirror Diagonal for Astronomical Telescope with 1.25 inches Adapter

Excellent Quality Dielectric Diagonal; Mirror Star Diagonal - 99% Reflectivity；Provides a Comfortable 90 Degree View from your Refractor; Fits Standard 2" (50.8 mm) Diameter Focus Tubes; Use Both 2" (50.8 mm) and 1.25" (31.75 mm) Eyepieces
New 2" 90 deg 99% Dielectric Mirror Diagonal for Telescope With 1.25" adapter; full metal;has a 1/10th wave flat optical glass surface;solid aluminum housing;threaded to accept standard 2" filters;The 2" eyepiece holder uses a non-marring brass compression ring to secure your valuable eyepieces. The 1.25" adapter also has a non-marring brass compression ring
Both sizes of eyepieces may be used and are protected from dings and scratches that would result from a standard set-screw. This 2" diagonal works with any Refractor that accepts a 2" star diagonals. It can also be used with Schmidt-Cassegrain or Maksutov-Cassegrain with an optional 2 inch visual back (See below)
Dielectric diagonal is especially important;A standard aluminized diagonal has about 92% reflectance;And this decreases with time as the aluminum mirror surface ages
For the vast majority of the visible spectrum;the reflectance does not vary more than about 0.1% below 100%;And the dielectric surface does not age like aluminum;This combination leads to the equivalent of a little more light grasp compared to standard diagonals

No. 6

Celestron 2-Inch XLT Diagonal Mirror (for SCT Telescope)

2” SCT mirror diagonal with high performance XLT coatings
1/10th wave mirror is tested with an interferometer to ensure quality
Housing is precision machined to achieve and hold good optical alignment.
Includes a 2” to 1.25” adapter and aluminum carry case

No. 7

$NEEWER 1.25in 45 Degree Prism Diagonal for Correct Image, 45° Refractive Optical Prism with 1.25' Eyepiece Adapter and Brass Rings for Astronomical Telescope, LT-T11$

NEEWER 1.25in 45 Degree Prism Diagonal for Correct Image, 45° Refractive Optical Prism with 1.25" Eyepiece Adapter and Brass Rings for Astronomical Telescope, LT-T11

【Suitable for 1.25" Eyepieces】 NEEWER LT-T11 45° Diagonal Prism is compatible with all 1.25" eyepieces and telescope focusers. (Note: The image is reversed when using a Newtonian telescope. It is due to the optical design of the Newtonian telescopes, not the product’s defect)
【Accurate Image Orientation】 Turn your refractor or Cassegrain telescope into a daytime terrestrial spotting scope and get a view that is correctly oriented, which means the image is upright and correct from left to right
【Comfortable 45° Viewing Angle】 It offers a wider 45° viewing angle on your astronomical telescope, so you can observe wildlife, landscape, sports events, and other objects in a convenient and comfortable position
【Bright and Sharp Images】 The premium multi-coated optical prism ensures bright and sharp images with exceptionally high color fidelity. The durable metal construction is ideal for outdoor observation
【Secure & Safe Installation】 Directly insert the silver end into a 1.25" telescope and fasten the telescope eyepiece with the screw knob. The copper ring offers great security and keeps the eyepiece free from scratches

No. 8

$NEEWER 1.25' 90° Zenith Diagonal Mirror, Erecting Image Positive Optic Mirror Adapter for Refractor and Catadioptric Astronomical Telescope Eyepiece$

NEEWER 1.25" 90° Zenith Diagonal Mirror, Erecting Image Positive Optic Mirror Adapter for Refractor and Catadioptric Astronomical Telescope Eyepiece

【Fit for 1.25" Eyepieces】 Compatible with all 1.25" eyepieces and telescope focusers
【Work with Refractor Telescopes】 This diagonal telescope mirror is only suitable for refractor and catadioptric telescopes, not recommended for reflector telescopes
【Achieve Optimal Positions】 When the diagonal mirror is installed on the vertical axis, you will see an upright image with a mirroring effect (left to right reversal). When installed on the horizontal axis, the image will appear in an upside down orientation. No matter how you install the diagonal mirror, you will get an optimal position for observing landscapes, wildlife, and astronomy
【Secure & Safe Installation】 Directly insert the silver end into a 1.25" telescope and fasten the telescope eyepiece with the screw knob. The copper ring offers great securing strength and keeps the eyepiece in pristine condition free from scratches
【Impeccable Image Quality】 The diagonal mirror is made of quality optical glass with coatings for crisp and sharp images as well as high color fidelity. The durable construction is suitable for outdoor use

No. 9

Astromania 2 Inch Diagonal 45-Degree Erect-Image Prism for Telescope - Image Erecting BAK4 Prism with Anti-Reflection Coating That Provides Sharp and Clear Image - with 2 to 1.25 Eyepiece Adapter

The BAK4 prism with an anti-reflective coating and integrated high-quality optical prism instead of a mirror enhances accuracy; making it ideal for precise astronomical observations and ensuring clear and sharp images
The inclusion of 2 Inch-1.25 inch adapters allows for seamless connectivity with both 1.25 Inch and 2 Inch accessories; catering to a wider range of requirements
This wide 45 degree angle makes you view correct image from telescope stand; makes it easier to observe
All aluminum black anodized with smooth surface and have long service life
The product has a matte black internal thread design to prevent stray light reflection; additionally; the attachment design includes brass clamping rings and large chrome-plated thumb screws for a safe and secure connection without causing damage

No. 10

Astromania Telescope Diagonal 2 Inch 90-Degree Diagonal Mirror 99% Reflective Dielectric Coating Erect Image with 1.25 Inch Adapter - Provide a Much Brighter Image Than with an Ordinary Star Diagonal

The 2 inch telescope diagonal features a 99 percent reflective surface; the optics are crafted from Pyrex glass; additionally; equipped with an SCT interface and a 1.25-inch adapter; significantly broadening the range of compatible telescopes and accessories
Multi Layered Dielectric Coatings: Dielectric coatings on the super-flat mirror reduce reflected light loss; providing a surface with over 99% reflectivity for brighter and harper images; which is highly beneficial for astronomical observations
Wide Compatibility: Suitable for refractors included Schmidt-Cassegrains; ACF; EdgeHD and Maksutov-Cassegrains; it can be connected to other eyepieces; barlow lens and filters; among other accessories; via a 1.25-inch adapter
90 Degrees Design: The Astromania 2 inch 90-Degree 99% Dielectric Diagonal Mirror adopts a 90 degrees design; which can provide you with a better observation experience during visual observation
Premium Aluminum Material: It is constructed from aluminum alloy; which significantly enhances the star diagonal longevity; equipped with brass compression ring; non-marring compression safety secures the eyepieces

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Last update on 2025-04-25 / Affiliate links / Images from Amazon Product Advertising API

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