Top 10 Best telescope diagonals in 2026

Last Updated - 6/12/2026

🏆Best Choice

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Astronomical Telescope Accessories D114F900mm with Short-axis Secondary Mirror 25mm, Newton Reflector Spherical Mirror

9.8

ChoiceComparer.com Score

9.8

/ 10

Outstanding

Main highlights

•1. Material: K9 glass
•2. Model: Main mirror D114F900 with auxiliary mirror 25mm
•3. Size: The main mirror diameter is 114mm, the focal length is 900mm, and the minor axis of the secondary mirror is 25mm.
•4. The surface is coated with aluminum film and aluminum oxide protective film
•5. Realistic shooting effect: can shoot planets

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$29.00

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starboosa

Starboosa Complete Telescope Eyepiece Set - Multi-Coated Optics - 1.25 inch Eyepiece Set with 4mm, 10mm, 20mm Lenses, 5X Barlow Lens, 2 Moon Filters, 2 Polarizing Filters

9.7

ChoiceComparer.com Score

9.7

/ 10

Outstanding

Main highlights

•**Comprehensive Eyepiece Set:** This 1.25-inch (31.7mm) eyepiece set is designed for astronomy professionals and beginners alike. It includes 4mm, 10mm, and 20mm eyepieces for versatile viewing, plus a 5x Barlow lens to significantly enhance magnification.
•**Added Filters for Optimal Viewing:** The set comes with 4 high-quality filters—2 moon filters and 2 polarizing filters. These filters provide better contrast and clarity when observing the moon, planets, and other celestial objects, reducing glare and enhancing details.
•**Upgraded Eyepieces with Soft Eyecups:** The eyepieces are equipped with soft eyecups, making extended viewing sessions more comfortable. The eyecups also help block out ambient light for a clearer, more focused observation experience.
•**High-Quality Optics:** The lenses are made from premium optical glass with multi-coating, delivering sharp, clear images with balanced chromatic correction. The result is a flat image plane with excellent color accuracy and minimal distortion.
•**Compatible with All Telescopes:** This eyepiece set supports a wide range of telescopes, including both reflector and refractor models. Whether you're observing the moon, star clusters, or distant planets, this set offers flexibility and enhanced viewing. If you encounter any issues, feel free to contact us by email for prompt support.

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$61.59

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UAIAGM

Erect Image Prism 1.25" Erecting Prism for Telescope 90-Degree Optical Prism with Clear Image Enhance Your Viewing Experience Makes Your Image Clear and Sharp

9.5

ChoiceComparer.com Score

9.5

/ 10

Outstanding

Main highlights

•Achieve a comfortable viewing angle with the 90-degree diagonal mirror designed for refractor and catadioptric telescopes
•Get clear and sharp images with fully coated lenses that come with a dust cover to keep them clean
•Insert and use easily with the 1.25in diameter that fits most telescope focuser and eyepieces
•Made of durable aluminum alloy, ensuring its longevity and protecting your investment
•Designed for refractor and catadioptric telescopes to achieve an upright, but reversed left and right image. Not recommended for reflector telescopes

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$13.29

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Talcope

Talcope Brightness Red Dot Finderscope, Star Pointer Viewfinder Astronomical Telescope Accessories with Slide-in Bracket

9.4

ChoiceComparer.com Score

9.4

/ 10

Excellent

Main highlights

•Easy to Use: This finder scope red dot sight comes with an adjustable that LED dot is projected onto a non-magnifying viewing window. It's easy to find the red dot because it contrasts well with the color of the lens material. So you can aim the main telescope quickly and easily.
•Adjustable red dot brightness: The star pointer brightness of the red dot is adjustable to different environments. It is bright enough to use during the day or night.
•Suitable for Most Astronomical Telescopes: Includes bracket that fits the dovetail mounting base on many telescopes; with a long-lasting CR2032 3V battery to ensure working life.
•Simple to Install: Red dot sighting device aiming your telescope is effective. Adjustment knobs work well, you evened up the finder with the adjustment knobs before you put it on your telescope. It was a breeze dialing it in.
•Quality Assurance: We provide a one-year after-sales guarantee. If you have any questions, please email us firstly. We will help you immediately.

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$17.99

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Acxico

Acxico 3Pcs/Set Universal 0.965inch/24.5mm Telescope Eyepiece Set H20mm H12.5mm SR4mm for Astronomy Photography Accessory Kits

9.2

ChoiceComparer.com Score

9.2

/ 10

Excellent

Main highlights

•Only for 0.965"/24.5mm Telescope Eyepiece Set.Multi-coated.Suitable for 0.965"/24.5mm telescope eyepiece filters.The lowest magnification being the H20 eyepiece, the second largest magnification being the H12.5 eyepiece, and the highest magnification being the SR4 eyepiece.
•Support all types of telescopes, reflector, refractor, to observe the star nebula cloudy cluster, moon, planet and deep sky, perfect for astronomy exploration.Wide viewing field with extra sharpness,35 Degree Field of View.
•Material：Optical Glass + Metal;Focal Length：20 mm(0.79 inch)/4mm(0.15 inch)/12.5 mm(0.49 inch);Eyepiece Port：24.5 mm/0.965 inch;H20mm Eyepiece Size：4.7*2.8 cm/1.85*1.10 inch;SR4mm Eyepiece Size：3.7*2.8 cm/1.46*1.10 inch;H12.5mm Eyepiece Size：4*2.7 cm/1.57*1.06 inch.
•Note: If you start using the highest magnification SR4mm eyepiece, the image may appear darker. This is normal because the eyepiece has a high magnification but a smaller field of view. When lighting conditions are poor, the image may appear darker due to the higher magnification.
•Instructions for using the eyepieces: Start with the lowest magnification eyepiece, the H20 eyepiece. If the image is unclear at a distance, switch to the H12.5 eyepiece for higher magnification. If the image is still unclear at a distance with the H12.5 eyepiece, you can switch to the highest magnification SR4 eyepiece.

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$14.59

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CELTICBIRD

CelticBird 0.965Inch Telescope Accessory Kit for 0.965 Telescope - Comes with Four Eyepieces（ 4mm/6mm/12.5mm/ 20mm ）, one Diagonal, a 3X Barlow Lens

9.1

ChoiceComparer.com Score

9.1

/ 10

Excellent

Main highlights

•It contains 4mm/6mm/12.5mm/ 20mm eyepiece, a 2x berlow lens and 90 degree diagonal.
•Barlow lens —— A visual Barlow, doubles the magnification of any inserted 0.965 inch eyepiece.
•4mm/6mm/12.5mm/ 20mm eyepieces ——for different power in any telescope.
•This six-piece 0.965inch astronomy accessory kit let you get the most out and enhances the performance of your telescope.
•A 90 degree diagonal.

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$38.99

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SupplySource

SupplySource 12V 5A AC/DC Adapter for Meade Instruments Universal # 07584 Telescopes 7" 8" 10" 12" LX90 LX200GPS LX200 LX200R LX200 GPS LX200 ACF LX 90 80 LX 200 LX850 LX850 ACF LX 850 LX80 Power

8.9

ChoiceComparer.com Score

8.9

/ 10

Great

Main highlights

•✔SAFETY: Supply Source Products manufactured with the highest quality materials and include multiple smart features safeguarding against IV - incorrect voltage, SC - short circuit, IO - internal overheating . Chargers are certificated with CE FCC etc.
•✔POWER SPECS - Input Volt Range: 100-240V / Input Frequency : 50-60Hz / Cable Length: 11FT
•✔NOTE: This Adapter is Brand New, High Quality Never USED (non-OEM). Please make sure the model of your device before buying
•✔12V 5A AC/DC Adapter For Meade Instruments Universal # 07584 Telescopes 7" 8" 10" 12" LX90 LX200GPS LX200 LX200R LX200 GPS LX200 ACF LX 90 80 LX 200 LX850 LX850 ACF LX 850 LX80 Power

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$14.99

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SVBONY

SVBONY Finder Scope 5x24 with Bracket Plastic Accessory Kit for Astronomy Telescope

8.8

ChoiceComparer.com Score

8.8

/ 10

Great

Main highlights

•The finder scope is a secondary scope that's used to help you locate objects in the main telescope;3 thumb screws allow positioning XY adjustment for precise telescope alignment
•It provide 5x24 low power magnification;the telescope fixed to the body of a more powerful telescope and pointed in the same direction for initially locating an object to be observed
•Tube has a glossy black metallic finish and cross hair reticle;includes mounting bracket and dust caps;the bracket fits any telescope optical tubes and the dust caps protects against dust and fingerprin
•Mounting bracket has curved base with two holes and attaches to telescope tube with bolts or screws;bracket will not slide into a dovetail base
•Wth it you are more convenient to find the star

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$11.69

$12.99

-10%

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

SVBONY

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

8.6

ChoiceComparer.com Score

8.6

/ 10

Good

Main highlights

•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.The image effect of this zenith mirror is positive up and down, and negative left and right.
•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

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$17.99

$19.99

-10%

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starboosa

Starboosa 1.25-inch 5X Barlow Lens & Moon Filter Kit-for Telescope Eyepieces

8.5

ChoiceComparer.com Score

8.5

/ 10

Good

Main highlights

•Barlow lens & moon filter, which are indispensable for astronomical telescopes, improve the working efficiency of eyepieces and expand the eyepiece magnification of 1.25-inch telescope to 2.5 times.
•5x Barlow lens has a magnification of 2.5 times in the actual measurement.
•Works with telescopes from Celestron, Skywatcher, Mead, Orion, and most brands.
•Universal M42 thread connection, you can also connect an SLR camera. Connect one end to the T-ring, then the SLR, and finally the entire assembly to the astronomical telescope to begin photography.
•Both the 5x Barlow lens and Moon Filter frame are processed by precision CNC. The anti-rust surface treatment is suitable for long-term use.

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$20.19

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