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View the Latest Diagonals & Prism Reviews

Item
Submitted By
William Optics SCT Thread Adapter for 2
William Optics SCT Thread Adapter for 2" Diagonal
5.0
Does what it needs to
Does what it needs to do.
William Optics 2
William Optics 2" 99% Dielectric Dura Bright Carbon Fiber Mirror Diagonal for Refractors
4.0
Well made unit
Super clear compared to stock Celestron 1.25 in. diagonal. Superb construction quality. A little tricky to mount the first time because the mating ring fully threaded onto telescope rear cell does not cinch the unit up tight to the scope. You need to...
GSO 2
GSO 2" 90-deg 99% Quartz Dielectric Mirror Diagonal for Refractors
5.0
GSO 2" dielectric diagonal
Upon opening the box I was impressed by the size and weight of the diagonal compared to 1.25" diagonals. That heft was the primary reason for the purchase, to give greater security and stability when using heavy eyepieces or camera. I also want ...
GSO 2
GSO 2" 90-deg 99% Dielectric Mirror Diagonal for Refractors
4.0
Inexpensive used on a ST80
Inexpensive used on a ST80 with 2" GSO focuser.
GSO 1.25
GSO 1.25" 90-deg 99% Dielectric Mirror Diagonal with Compression Ring
5.0
A good diagonal
Works good and fits nicely on my smaller scope
William Optics 1.25
William Optics 1.25" 90-deg Erecting Prism Diagonal with Helical Focusing # D-EP90-125
5.0
Very useful with good views over mirrors for planets
I bought this on a whim because I read another comment about this diagonal's helical focuser being helpful in keeping the main focuser from extending too far out and throwing off balance. Well, it does that to some degree, and certainly helps me...
Celestron 1.25
Celestron 1.25" Telescope Star Diagonal # 94115-A
3.0
Not so great.
These are now too cheaply made. The thumbwheels stick up above the edge of the tube, so collide with some eyepieces, and the thumbscrews are very loose and the threads may strip out with not much use. This one is now in my "spares" box. Rep...
GSO 2
GSO 2" 90-deg 99% Quartz Dielectric Mirror Diagonal for SCTs
5.0
GSO 2” diagonal
Very nice heavy duty, works much better than standard Meade diagonal
William Optics 1.25
William Optics 1.25" 90-deg Erecting Prism Diagonal with Helical Focusing # D-EP90-125
1.0
Two Defective Units
Regrettably, I can't give this diagonal a good review. It is well designed and very solid, as all Williams Optics products are. The eyepiece holder is a high quality compression ring type with a nice large thumb screw, and the helical focuser is...
GSO 1.25
GSO 1.25" 90-deg Erect Image Amici Prism Diagonal # PD90
4.0
Prisme redresseur à 90°/1,25" = 90/1,25" Erecting prism
Un bon produit qui remplace le modèle de la marque Celestron, que l'on ne trouve plus qu"en occasion. The Celestron erecting prism (same function) is no longer avalaible. This model is a solution of replacement ; it works correctly and i d...
GSO 2
GSO 2" 90-deg 99% Dielectric Mirror Diagonal for Refractors
3.0
not to pleased
The edges are sharp almost to the point of needing some tape to cover them. And the 1.25 adapter set up with the set screw having to go in the slot is a pain in the dark.
Overall the view is fine.,the construction.,design is poor.
GSO 2
GSO 2" 90-deg 99% Dielectric Mirror Diagonal for SCTs
5.0
GSO 2" Mirror Diagonal (99% Dielectric)
Superb diagonal - meets and exceeds my intermediate level observing requirements. HIGHEST QUALITY - excellent workmanship and materials, fit and finish. WORKS SUPERBLY. Highly recommended for anyone who needs a really good 2" diagonal. MP Ballst...
GSO 2
GSO 2" 90-deg Mirror Diagonal for Refractors
5.0
2" GSO 90* Mirror Diagonal
Great deal for price. Using on my 102mm, F/6.5 RFT refractor with a GSO 30mm Superview eyepiece. Love it.
William Optics 2
William Optics 2" 99% Dura Bright RotoLock Mirror Diagonal for Refractors #...
5.0
Dignified way to attach accessories
I have a lot of stuff stacked on the back of my SCT and the RotoLock is the most secure feeling part of it all. This is attached to the back of the SCT with the other accessories on top of it so I can still swing to dec 0. This diagonal sits much clo...
GSO 1.25
GSO 1.25" 90-deg 99% Dielectric Mirror Diagonal with Compression Ring
5.0
Not bad at all :)
I am quite satisfied with this diagonal, which is clearly one class over the standard "kit" ones (i'm talking about the metal case diagonals, not plastic ones, of course), in terms of build quality and optical performance. I'm ye...
Baader T-2 90° Prism Star Diagonal Body # T2-01C 2456005
Baader T-2 90° Prism Star Diagonal Body # T2-01C 2456005
5.0
Binoviewer Enabler
Using this diagonal to shorten the light path for my binoviewer. Back focus was always a problem but now I can achieve focus on both my st80 and st120 without shortening the tube. Add in a 2” T2 nosepiece and a custom T2 binoviewer adapter and you...
Baader T-2 90° Prism Star Diagonal Body with Carl Zeiss Prism # T2-01B 2456095
Baader T-2 90° Prism Star Diagonal Body with Carl Zeiss Prism # T2-01B 2456095
5.0
Baader Zeiss spec prism diagonal
I use this with 1.25" and 2" nosepieces and with Eyehold 2 at the eyepiece end. I've primarily used it with SCTs to date and a small refractor. I have had the Baader Prism-1 for the past year and it was fun to compare it with this Zeis...
Celestron 1.25
Celestron 1.25" Telescope Star Diagonal # 94115-A
5.0
Great right angle prism
Perfect for my C90, and very affordable.
GSO 1.25
GSO 1.25" 90-deg Mirror Star Diagonal for Refractors # GSST
5.0
Great item at a great
Great item at a great price.
William Optics 1.25
William Optics 1.25" 90-deg Erecting Prism Diagonal with Helical Focusing # D-EP90-125
5.0
Fine Focus.
Helical Focus was the sole reason I got this diagonal. It compliments the regular focus on my scope. It worked exactly as I hoped it would.