William Optics 1.25'' DURA-BRIGHT Dielectric Diagonal

William Optics 1.25" DURA-BRIGHT Dielectric Diagonal

  (13 Reviews)
✓ 2 year warranty


5x in stock shipped 1-2 working days

About this product

Model:  WOdielectric125
Part Number:  D-125D-C-DB

Offers a noticeable improvement in brightness, contrast and overall sharpness when compared to budget diagonals!

  • Dura-Bright thick mirror and dielectric mirror coatings for 99% reflectivity.
  • Precision 1/12 lambda surface accuracy.
  • 12mm-thick mirror substrate.
  • Threaded to accept 1.25" filters.
  • Compression ring to prevent barrels’ marring.
  • Internal safety stop prevents 1.25” barrels from hitting the mirror.

Introducing New 2014 model William Optics Dura-Bright diagonal - a dramatic step forward in the evolution of mirror diagonals! This 90° 1.25"mirror-type star diagonal has a Dura-Bright thick mirror and dielectric mirror coatings for 99% reflectivity which provides higher contrast and resolution during critical planetary, lunar and binary star observations.

Dura-Bright features 100% real carbon fiber side plates that add that touch of class your scope deserves.

The WO 1.25" Dura-Bright Diagonal was designed with several unique features to provide optimum performance and years of use.

Top-Notch Performance and brightness
• Dielectric coating allows 99% reflectivity.
• high precision 12mm thick mirror substrate flat for optimal image stability.
• Polished to 1/12th wave accuracy.
• Accurate design guarantees constant alignment. No further alignment needed.

Meticulous Craftsmanship
• Lock screw for eyepiece/adapter.
• Big, knurled thumbscrews are easy to turn even with gloves on.
• Threaded for 1.25" Filters.

Strikingly Beautiful
• Patented, elegant design.
• High-quality machining out of the best Aluminium.
• Internal antireflection baffling for highest contrast.
• Real Carbon Fibre side plates

Superbly Constructed
• Compression rings (both on diagonal and adapter) to prevent barrels from marring.
• Internal safety stop prevents 2" barrels from hitting the mirror.
• Designed for high-end scopes.


ReflectivityUltra High Dielectric 99% reflectivity.
MirrorPrecision 1/10 lambda surface with 12mm thickness mirror for best quality.
Accessories2"- 1.25" adapter with brass clamping ring,includes
MeasurementsInside diameter (48mm): threaded to fit a variety of filters.
WeightWeight : 210g

Customer reviews

Average Rating (13 Reviews):  
Write a Review and share your opinions!

Rating (max 5):  
This Transformed the Optics Path of my Skymax 127...
Friday, 12 February 2021  | 

I bought a Skywatcher Skymax 127 a few weeks ago as my first OTA... I had studied many forums and watched hours of YouTube in deciding which scope to invest in... I decided on a MAK as itís great for planetary and Lunar viewing and also because itís a compact and Ďeasy to useí device. I was delighted with the performance of the scope but, inevitably, after using it a few times I wondered if I could make a few improvements by replacing some of the included Ďaccessoriesí. The supplied 25mm EP was quite good but the Skywatcher 10mm EP was horrible so, on the recommendation of FLO, I purchased a couple of BST eyepieces and discovered just how Ďaverageí the supplied EPs were! I also replaced the finder scope with a Baader Red Dot Finder and that also was a marked improvement. Then it occurred to me that the optics in the OTA were superb and also the new BST eyepiece was great but sat in between them was the Ďstockí Skywatcher Diagonal. After spending hours on forums (again) I was a little unclear as to whether buying a high-quality Diagonal would be worth the investment. In the end I decided to go for it, especially as the William Optics Diagonal had some great reviews for build quality and they are renowned for producing excellent optics.
I thought there might be some improvement but the difference, compared to the supplied Skywatcher item, is quite dramatic... looking at rooftops about a mile away itís a crystal clear image, where before it was ok but not really filling the full eyepiece with a quality image, itís also so much brighter...
Iíve yet to get a clear sky to try it out at night but itís just obvious that itís going to be a big improvement...
A few people on blogs are sceptical about this upgrade but for my Skymax 127, which has great optics in the tube, itís really allowing the OTA to do itís job... Brilliant!
If you have a Skymax 127 or you are considering buying one then fitting this diagonal is simply a no-brainer; it dramatically improves on an, already, good viewing experience and turns it into something quite special.
A lot of experienced people on various forums will claim that the improvement with a diagonal upgrade is small but on my Skymax 127 it has transformed what you see in the eyepiece...
I also now have an item that can be used with a high-end scope in the future... happy days...

Rating (max 5):  
William Optics 1.25" DURA-BRIGHT Dielectric Diagonal
Friday, 4 December 2020  | 

Quality diagonal that delivers improved performance. Definite increase in brightness in the viewed image, and a good choice as an upgrade to the supplied star diagonal.

Rating (max 5):  
Tuesday, 8 September 2020  | 

Not been used much due to cloudy skies locally. Excellent quality build as you would expect from this provider. Wonderful customer service as always from FLO, thanks all!

Rating (max 5):  
Very high quality
Wednesday, 12 August 2020  | 

Exactly what you would expect from William Optics. Well designed and beautifully made.

Rating (max 5):  
First Class Service
Tuesday, 5 May 2020  | 

First purchase from FLO, faultless transaction, fast and efficient. Just purchased more items. Highly recommended. Thank you.

Rating (max 5):  
William Optics 1.25" DURA-BRIGHT Dielectric Diagonal
Friday, 7 February 2020  | 

I spent sometime reviewing a number of Diagonals to replace my standard issue 1.25 Celestron one, which came with my Nextstar SLT 6" SCT. Really in the end, I kind of narrowed it down to a Celestron "Twist-Lock", Tele-Vue or WO DURA-BRIGHT.

Well, I could have spent over £50 or more on the Tele-Vue, but when I ordered and received the WO DURA-BRIGHT (very nicely packed by FLO) I was very impressed!! Firstly, if you compare your Diagonal which was supplied with your Scope, (just look through it with your eyeball) with the DURA-BRIGHT, the difference is blatantly OBVIOUS. The Image is Bright and has More Contrast. The Build Quality is very good, and I had NO problems extracting my Celestron X-Cel LX eyepieces (some people mentioned issues with the compression ring, binding on the eyepiece undercut, with this type of locking system, which is used by several manufacturers by the way) all I can say is, I haven't found any Problem as such, just don't over tighten the locking Screw, and a very slight lift and wiggle, as you extract the eyepiece, if you ever find it necessary I suppose.).

Rating (max 5):  
So good I purchased this twice!
Wednesday, 4 September 2019  | 

When I purchased my Tak 76 in 2016, I needed a high quality diagonal to go with it; I travel a lot so only use 1.25 eyepieces, Ian King had sold out of the Tak prisms, and suggested that this was a great quality diagonal. It's been superb, traveled lots with it, used extensively at Seething, the Astro Camp and the Astro Fam in Confolens for a Messier Marathon...Sadly, I managed to break my original in the early hours of one morning. FLO was the first website I went to, to replace it. High quality, lightweight and well made; holds my 24mm Panoptic and 9mm Nagler with ease, has a compression ring (i think that's the term) so you don't make marks onto the barrel of the eyepieces. The barrel that you insert into the telescope will unscrew, which is perfect for helping you blow away any dust that will accumulate after many uses...Has a 2 year guarantee, and unless you're a "butterfingers" should last a long time!

Rating (max 5):  
Could Not Resist !
Friday, 19 October 2018  | 

As soon as I took my Celestron Edge telescope out of it's box I knew I wanted to upgrade certain items. I'm just like that... This diagonal looked the part on the website and face to face it does not disappoint. Excellent build quality and superb looking clear mirror. The fixing look more substantial too. I am fully trusting this to hold my Vixen eyepieces and to look good while doing it. Recommended !!

Rating (max 5):  
Great Product
Wednesday, 13 June 2018  | 

Great Product

Rating (max 5):  
Great product.
Tuesday, 6 February 2018  | 

Great product, great service! But I wish they'd stop asking for feedback every time I buy something!!

Read all 13 customer reviews...


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