TPO 2" Quartz Dielectric Diagonal

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  • $116.06
  • Regular price $128.95

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  • Quartz offers greater thermal stability, resulting in minimal thermal expansion and contraction.
  • The Third Planet Optics 2 inch Quartz Dielectric Diagonal is a deluxe 1/10th wave mirror diagonal with 99% reflectivity, dielectric coatings.
  • Fully CNC machined housing and includes 2 inch to 1.25 inch adapter.
  • The TPO 2 inch Quartz Dielectric Diagonal features brass compression rings on both the diagonal and adapter assure gentle treatment of your eyepieces.
  • Fully machine threaded to accept 2 inch filters.


TPO 2" Quartz Dielectric Diagonal

The TPO 2 inch quartz dielectric mirror diagonal features 99% reflectivity, dielectric coatings to maximize light output of your telescope system. Our custom made diagonal uses a quartz mirror polished to 10th wave accuracy (or better) for best possible image quality.

TPO's quartz dielectric diagonal provides greater thermal stability than comparable glass diagonals, resulting in minimal thermal expansion and contraction. This quartz diagonal, therefore, minimizes focus position change due to variations in temperature.

The Third Planet Optics 2 inch quartz dielectric diagonal also features a CNC machined housing. The CNC machined aluminum housing will provide outstanding results for years of use. This housing is designed to retain the optimal collimation of the mirror and assure the best optical performance.

This diagonal also includes brass compression rings on both diagonal and the included 2 inch to 1.25 inch adapter, assuring gentle treatment of your eyepieces. Some other brands use set screw locking mechanisms that can mar the barrel surface of your favorite eyepieces. Avoid scratches and gouges by using the OPT dielectric series diagonals.

TPO quartz dielectric diagonals provide outstanding performance with low prices to provide amateur astronomers with excellent value! OPT backs this diagonal with a full 2 year warranty against manufacturer defects.

TPO Product Number: OS-D2DIQ


Accessory TypeDiagonals
Free ShippingYes
Warranty2 Year Warranty

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Ask a Question
  • Would this be my best choice for an ES127 refractor?

    Good afternoon and thanks for asking. That is certainly a very good choice but I might also suggest the Explore Scientific 2" diagonal, ES-DD02-00CF.

  • Is this an all-Quartz mirror with dielectric coatings? Or is it a quartz-protected aluminized mirror with dielectric coatings? Seems cheap for an all-Quartz design.

    According to the manufacturer, the mirror is an all quartz substrate with dielectric coatings.

  • I need a 2" Visual back to attach this to my celestrion nexstar 5 se. what do you have that will work for me????????//

    This diagonal can be used with the OS-ASCT2 2" visual back on most SCT scopes 5" and larger