William Optics 90° Erecting Prism with helical focuser for fine adjustment.
Turns upside-down views right-side-up and gives correct left-to-right orientation.
Works with 1.25" eyepieces and telescopes with 1.25" eyepiece holders.
|Average Rating (5 Reviews): |Great alternate to dual focuser!
Saturday, 2 June 2018 | Simon
This is a great bit of kit if you don't want to upgrade to a 2 inch or 10:1 focuser, helical action is very smooth, and really helps fine focus, and even though its an erect image In think it performs as good as or better that a star diagonal. I use it coupled with my st80 & evo 90 and makes a great addition! Also used with a baader T2 1.25 eyepiece holder which holds it well and prevents slippage and marking on the nose piece. Flo very helpful, and kept me updated on delivery!
Great Product at a great price
Wednesday, 28 February 2018 | Charles
This is a very good erecting prism. My intention was to use it in my Baader Varifinder, but it is so much more than a simple erecting prism, making it an ideal match for a high quality refractor for terrestrial viewing. Recommended!
William Optics 90 degree prism
Thursday, 25 January 2018 | Colin
Very useful piece of well-engineered kit. Optically excellent and the addition of the helical focuser to my telescope has made a huge improvement. Highly recommended.
Wednesday, 25 May 2016 | Philip
OK not everyone wants an erecting prism but I did! The build quality of this 90° prism is very solid and the optics are good with no perceivable aberrations to my ageing eyes. Much better than the 45° prism that came with my scope. Also the inbuilt helical focuser is a bonus and acts as a fine focus once the scope is focused and does not vibrate the set up. I now don't get back ache with this 90° diagonal in place - highly recommended for quality with ecconomical cost.
Alternative to dual focusers
Friday, 8 January 2016 | Nick
Wonderfully built and with smooth action. A lovely alternative solution if you have a stock rack and pinion focuser. Especially so if you want to keep the original look of a classic refractor.
It gives very fine focussing equivalent to dual speed. The prism provides correct views with minimal effect on observing. We compared it with a WO dielectric on the double star Wasat and found it hard to find any difference in views.
Will definately recommend this as value for money and an essential bit of kit.