We are closed from 20/12/24 to 03/01/25 most orders placed when we are closed will not ship until the New Year.
Show Store Sections+
Show Information+
Account+
Home Accessories Diagonals Telescope Diagonals For Astronomy Altair 2 Inch Positive Lock 90 Degree Prism Diagonal
Quality prism diagonals give far light less scatter than coated mirrors and therefore better contrast than any diagonals using reflective mirror surfaces, including dielectric ones. Prism diagonals are therefore especially good for high power planetary and lunar observing where sharpness and contrast are critical, especially with high quality refractors with an F7 or longer focal ratio. Perfect for serious planetary observers wanting a low scatter premium prism with superb mechanics to match.Advantages of a PrismUnlike a prism, regardless of the coating methods used, all reflecting mirrors produced consist of tiny particles evaporated or deposited onto glass which, no matter how carefully deposited, will produce scatter and reduce contrast as the light "scatters". Another distinct adavantage of a quality coated prism is cleaning, durability is excellent with no long term loss of reflectivity like a mirror, cleaning can be performed in the same way as with any lens or eyepiece.The Altair prism diagonal has a BK7/K9 prism with excellent clarity and smoothness, as well as special anti reflective coatings.The prism surface cannot even be seen with the naked eye when looking into the diagonal, unless there is dust on the surface. The special "Positive Lock" compression ring will never mar your accessories and is completely secure. Ideal for refractors and large eyepieces or binoviewers. Top quality prism with special broadband multi-coatings. Clear aperture of 43mm, with an optical path distance of 125mm. Essentially maintenance free. Includes a 2" to 1.25" adapter with brass compression ring for smaller 1.25" eyepieces or accessories Threaded for use with standard 2" astro filters (M48x0.75mm thread). Blackened interior for high contrast (especially recommended for the moon, sun and planets!). Includes dust caps both ends.
High quality Arrived rapidly and well packaged from Harrisons. One of the heavier diagonals, goes nicely with my evostar 150. Feels robust and well-made. (15/05/2024) -
altair 90 degree prism bought this Altair 90 degree prism, from Harrison brilliant telescopes. The build quality is beautiful its a bit heavier than the mirror one i have feels really solid. had only one night to try it out the seeing was very poor, so need a good night to test it. delivery was brilliant. thanks Harrisons (24/09/2023) Dave Mole - Merseyside
Altair Diagonal Amazing service from Harrison, thank you for answering all the questions from a beginner lol. Product is excellent and service first class (12/04/2023) Animes - Orpington
Well worth the money prism diagonal After much concideretions I finally decided on this Altair 2 prism diagonal. I chose Harrison telescopes followed by good reviews about this company. The diagonal arrived next day by nice supprise very well packed. This diagonal is amazing quality,no false colours and super bright and sharp views (13/03/2022) Darek - London
Altair prism diagonal Received mine today,real nice quality and feel,the twistlock is smoother than my baadar twistlock. Not tried it yet but I know it'll perform well.very pleased . (05/01/2022) Chris - Leicestershire
My first 2 inch diagonal and it's quality compared to my stock one is amazing. (26/10/2021) Paul - Durham
Excellent product excellent service A good solid "chunky" piece of equipment that oozes quality and as always the speed of delivery was excellent. Thank you (01/08/2020) David Roe - Ugborough
Great diagonal I got this diagonal for use with my 8 meade SCT telescope and it fittered perfectly. The Altair 2 inch diagonal is really a solid piece of kit and I know I'll be using this for years to come (30/05/2020) Gunter - London
A solid high quality item This is my first 2" diagonal and I was influenced by the previous reviewer who is obviously more experienced. This is a solid high quality product and despite the weight Harrison's delivery charges are still about a third of that charged by other well known dealers and it still arrived the next day. (21/06/2019) Graham Shimmin - Herefordshire
I was looking for two reasonably priced star diagonals that I could use as work horses. I currently owned at the time, and still do, the handmade Vernonscope mirror star diagonal ( consider the finest diagonal in the world….and the price really does reflect this quality.) After a lengthy chat with Ed, he convinced me he had a diagonal that would give any other star diagonal a run for its money……. he really was not kidding! He had some Quality prism diagonals in stock, made by a UK company called Altair, at a price I considered insanely reasonable. I took a leap of faith and bought one, and tried it out……. within 24 hours I was back for a second one. Folks, The build quality are fantastic! The performance of the Altair prism diagonal, combined with my orthoscopic eyepieces, and used on my apo-refractor telescopes do not disappoint. These diagonals are brilliant! (15/11/2018) James Howes - london
View
01356 660401
