Enjoy better views through your telescope and change eyepieces and accessories faster and more easily with the Celestron 90° Dielectric Star Diagonal. The diagonal has a 1.25" nosepiece and holder to make it compatible with the most popular size of gear from eyepieces to Barlows, filters, and a near-infinite array of accessories.

Designed with diffraction-limiting optics, its BK7 mirror is treated with 58 layers of dielectric coatings that produce a reflective surface greater than 99% so more incoming light makes it to your eye—this is especially important when viewing dim deep-sky objects where every photon of light is important.

For the eyepiece holder side of the diagonal, Celestron eschews convention and replaces the ubiquitous three thumbscrews to tighten the interior compression ring with a twist-lock. Utilizing a twist-lock not only makes swapping your eyepieces and accessories faster and easier, it properly centers the eyepiece and maintains proper optical alignment. The nosepiece is outfitted with standard filter threads so you can install your favorite filter—like a moon, nebula, or light pollution—without having to move it from one eyepiece to another as you go about your observation sessions. The aluminum housing has a black anodized finish, and the interior is painted flat black with blackened threads to reduce reflections.

1.25" Nose Piece and Holder    BK7 Glass, Diffraction-Limited Optics    58-Layer Dielectric Coatings    Over 99% Reflective Mirror Surfaces    Twist-Lock Maintains Optical Alignment    Black Anodized Aluminum Housing    Filter Threads on Nosepiece

Related Questions and Answers

Q: 1. Can this be used on a 150mm Maksutov?

A: Yes, the Celestron 90° Dielectric Star Diagonal with Twist-Lock (2"), features a 1.25 "reducer, and will fit on the eyepiece holder of the 150mm Maksutov telescope.

Q: 2. How does it change the up/down, left/right view of the image?

A: The Celestron 90° Dielectric Star Diagonal with Twist-Lock (1.25") does not have the ability to change the view. It is not an erect image diagonal.

Q: 3. Can this be used to replace the diagonal that comes with the Celestron C90?

A: Yes it can

Q: 4. Is it work with celestron nexstar 8se? Is it necessary to buy any additional adapter?

A: No it will only attach toa 2"thread which the 8SE does not have.

Q: 5. Just purchased the iOptron Photon 6". Not using the SCT adapter, will this attach to the scope's focuser w/o a visual back?

A: The Celestron 90° Dielectric Star Diagonal with Twist-Lock (2") can attach directly to the focuser of the iOptron Photron 6" via its 2" nosepiece. If not achieving focus, one can use the iOptron extension rings to get the correct backfocus distance.

Q: 6. Hi. For a Celestron Nextstar 8SE telescope, will upgrading to this star diagonal make a significant improvement to viewing quality and/or photography quality?

A: The term "significant improvement" is such a personal reference. For me unless I switch to 2" eyepieces was there a significant improvement for me.

Q: 7. Can this diagonal be used on a Newtonian 114mm telescope

A: No, it is not possible to use the Celestron 90° Star Diagonal (1.25") with a Newtonian Reflector Telescope.

Q: 8. Can this product be attached to the NextStar 6 SE?

A: Yes, you can use the Dielectric Star diagonal 2" item # 93573. However, keep in mind that the opening of the Nexstar 6 is smaller than an 8 inch telescope and you will not get the full benefit of the 2" wide view.

Q: 9. Is it a Mirror diagonal or a prism diagonal ?

A: It is a mirror diagonal. The image is upright but not corrected left to right.

Q: 10. does it give same performance if I use 1.25 eyepiece. or if I use 1.25 diagonal with 1.25 eyepiece. which one has better performance?

A: This is an upgraded Diagonal compared to the Diagonal shipped as standard equipment with Celestron Telescopes and will give improved performance with both 1.25 and 2 inch eyepieces. This diagonal should provide improved performance over most 1.25 Diagonals and will be more versatile.