The SVBONY SV188P is a solid and attractively priced option for amateur astronomers who value good image quality and comfortable observation at the zenith. The combination of dielectric coating, sturdy metal housing, and 90° angle makes it a recommended addition to a good refractor telescope. If you plan to look up overhead more often or simply want to replace the standard diagonal mirrors, this model is worth considering.

Technical features

Here is an overview of the most important features of the SV188P:

• Dielectric coating: The mirror is equipped with a multi-layer dielectric filter, which, according to the manufacturer, achieves a reflection of over 99%, minimizing light loss. Svbony+2AstroGear+2
• 90° viewing angle: The diagonal mirror reflects the light path in the telescope by 90 degrees, which makes observing objects at the zenith (i.e., high in the sky) much more comfortable. Svbony+1
• Connection size: There are versions for 1.25-inch eyepieces; according to the manufacturer, there are also versions with 2-inch eyepieces. Svbony
• Mechanics & construction: Aluminum alloy metal housing, brass compression ring for secure eyepiece mounting, thread for use with 1.25-inch filters. Svbony+1
• Image orientation: When in use, an upright image is displayed (i.e., not rotated 180 degrees), although it may be mirrored left-to-right (“mirror image”) depending on the setup. Amazon+1
• Advantages & area of application

The SV188P is particularly suitable in the following situations:

• If you are observing with a refractor or a compact Cassegrain system and often want to view objects high in the sky (at the zenith) – the 90° angle makes it easier to observe comfortably without straining your neck.
• If you want good image quality and want to replace the standard diagonal mirrors of your telescope to achieve better brightness and contrast – many users report that the quality is visibly better. Svbony+1
• If you rely on filters, Barlow lenses, or other 1.25" accessories, as the thread is available.

Notes & possible limitations

There are a few things you should keep in mind when using it:

• Although the reflection is very high, the actual image quality naturally also depends on the telescope, eyepiece, seeing, and adjustment. A high-quality diagonal mirror alone does not work miracles – but it can be a useful improvement.
• There may be limitations for Newtonian reflector telescopes or very large apertures – for example, the manufacturer of the “SV188” (similar model) points out that it is “not suitable for reflectors due to its length.” Svbony So check whether your system is compatible.
• Left-right mirroring: Although the image is upright, horizontal mirroring can occur – this can be disruptive in some applications (e.g., photography with eyepiece projection).
• Sizes and connections: Make sure you have the right version (1.25“ or 2”) and whether adapters are necessary.

Scope of Delivery:

• Diagonal Mirror (1.25“ or 2”, depending on order)