SV188P 90 Degree Dielectric Mirror Diagonal 99% Reflectivity for Refractor Telescope

SKU: F9171B

US$ 34.99 -30%

List Price: ~~US$ 49.99~~

Dielectric coatings; super flat mirror with dielectric coatings to reduce reflected light loss; provide an over 99% reflective surface; good for astronomical viewing;
The 1.25-inch nosepiece fits 1.25-inch telescopes and accepts standard 1.25-inch filters, eyepieces, Barlow lenses, and similar accessories; The 2-inch nosepiece is compatible with 2-inch telescopes and accommodates standard 2-inch filters and accessories. You can choose either 1.25inch or 2inch diagonal based on your requirements;
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.

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Pre-sale on Apr 08,2025

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1.25inch 2inch

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SV188P 1.25inch 90 Degree Dielectric Diagonal for Refractor Telescope

Elevate your stargazing experience with the SV188P diagonal featuring dielectric coatings that provides over 99% reflectivity, significantly reducing light loss for brighter images.

1.25inch Diagonal

1.25in nosepiece fits telescopes with 1.25in focusers. Accepts standard 1.25” eyepieces, filters, Barlow lenses and other accessories with a 1.25in insert barrel.

90° Viewing Angle

For more comfortable overhead viewing through refractor and Cassegrain type telescopes.

Upright Image

Correct upside down and left right reversed image. It will look like trying to read a sign in a mirror. Suitable for space viewing, for there is NO upside down or right side up in space.

Brass Compression Ring

Brass lock Screw for eyepiece or adapter and brass Compression rings features more precision and prevent barrels or the surface of eyepieces from marring and scratching.

SV188P installed on the telescope

7 reviews

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Great Upgrade

Erick Flores on Feb 01,2025

Arrived in excellent conditions!, i have a refractor telescope, and it is a great upgrade for my equipment!!

Best upgrade

Meggabah on Jun 06,2024

If you have the basic diagonal that came with your telescope then get this one. Very bright image compared to the stock one. I love the over size knob on the eyepiece lock. Worked great with gloves on in winter. The compression ring was awesome as well. With those two features it makes this a great value and a good addition to your scope

Great Diagonal

Emilio Monelli on Jan 10,2024

Arrived well packaged. Well built diagonal, indispensable combined with my SV503 102ED

Little and perfect

Daniel Hocza on May 10,2023

EN: It's very light but still has substance. Excellent workmanship. It is decorative and fully fulfills its function. The mirror image is flawless. I wouldn't believe it if it was even better. I recommend to everyone. HUN: Nagyon könnyű de mégis van benne anyag. Kiváló kivitelezés. Dekorativ és funcióját maradéktalanul betölti. A tükör képe hibátlan. Ha ennél is jobb volna nem hinném el. Mindenkinek ajánlom.

Great piece!

Hartmut Schönherr on Dec 04,2021

Perfect product with excellent features. And sustainable package, without needless papers and prospects and plastic. But please tell your customers, which adapter is needed for Cassegrain - and give the link to the product in your shop!

Bright and contrasty

Skywatcher Simon on Aug 19,2021

I bought the 1.25 "mirror to be able to look into the zenith on my previous telescope. In contrast to a simple zenith mirror, the Svbony SV188P Dielectric Diagonal is a real win. The image is visibly brighter and the image quality at high magnification has also improved. Thanks to the ring clamp, the eyepieces remain free from scratches. Overall a very good mirror!

Diagonal dieléctrica

Daniel on Jun 21,2021

Buenas me gustaría saber cuál es el adaptador especial para la.diagonal dieléctrica sv188 P . Gracias.

Brand	SVBONY
Model Number	SV188P
SKU	F9171B	F9171D
Size	1.25inch	2inch
Optical Design	Mirror Diagonal	Mirror Diagonal
Coatings	Dielectric
Reflectivity	dielectric 99% coating for bright images
Material	Aluminum Alloy
Filter Threads	M28.5*0.6	M48x0.75
M4 Set Screws	Yes
Outer Connection(Lens Sided)	Barrel 1.25inch	Barrel 2inch
Inner Connection(Lens Sided)	Thread M28.5x0.6	Thread M48x0.75
Inner Connection(Eyepiece Sided)	Clamp 1.25inch	Clamp 2inch
Reflection Surface	Dielectrically Coated
Image Orientation	Erect Image, Mirror Inverted
Thickness of Mirror	11mm
Net Weight	125g / 4.41oz	463g

There are many 1.25" star diagonals on the market. Many of them have a mediocre mirror quality with 90% reflectivity (10% loss) and a plastic body. The 1.25" diagonal by SVBONY stands for a high-quality alternative to those cheap parts. It offers excellent image and mechanical quality. There's no vignetting over the full 1.25" field. SV188P features sophisticated, Multi-layered dielectric coatings that provide an outstanding 99% reflectivity for maximum view brightness and sharpness;
SV188P Diagonals provides a comfortable 90-degree viewing orientation when observing the night sky through a refractor. When use the SV188P with Maksutov-Cassegrain (Mak-Cass) or Schmidt-Cassegrain telescope, you need a special adapter;
Another advantage is the 1.25" nosepiece barrel is threaded to accept 1.25-Inch filters. Brass lock Screw and Brass Compression Rings feature more precision and prevent barrels or the surface of eyepieces from marring and scratching.