GSO 2" 90-deg 99% Dielectric Mirror Diagonal for Refractors

5.0 GSO 2" Dielectric Star Diagonal

Works as intended; no discernible reduction in image brightness; makes viewing objects near zenith much more comfortable; best price I could find on the web for a 2" dielectric diagonal. All of the GSO products I've bought to date are of high quality.

This review was provided courtesy of AgenaAstro.com

5.0 Same Quality, better price

I’ve had more expensive diagonals and the quality of this diagonal places it in the same league as the more costly ones.

This review was provided courtesy of AgenaAstro.com

5.0 Excellent!

Bought this because my GSO 2" refractor focuser, installed on my Orion StarBlast 90mm f/7.3 achro, didn't have enough in-travel to reach focus. The deep set adapter on this diagonal fixed that, and now everything is perfect. The diagonal itself is well-made and of high quality. An outstanding product!

This review was provided courtesy of AgenaAstro.com

5.0 Another great eyepiece from Agena!

Highly recommend!!!! 5-stars

This review was provided courtesy of AgenaAstro.com

5.0 GREAT 2" MIRROR DIAGONAL YIELDING OUTSTANDING LIGHT THROUGHPUT

I HAVE OWNED MANY 'ENHANCED' MIRROR DIAGONALS FROM 1 1/4" TO 2". I'VE OWNED MOST ALL FROM EVERY MANUFACTURE YOU CAN NAME, AND SOME YOU CAN'T. THIS IS A STELLAR PERFORMER AT A GREAT PRICE! I USE THIS IN A GSO 6" CASSEGRAIN.

WHILE IT DOESN'T FEATURE A TAPERED NOSE-PIECE, IT FEATURES COMPRESSION RINGS AND THE TWO SCREWS THAT LOCK THIS INTO PLACE ON THE CASS ALSO USE COMPRESSION RINGS, IT ISN'T GOING ANYWHERE UNLESS YOU WANT IT TO. THE 1/12TH WAVE OPTICS AND 99% REFLECTIVITY WITH BK-7 GLASS GIVE THIS SCOPE, THAT HAS QUARTZ OPTICS AND 96% REFLECTIVITY, THE EQUAL OF A 7" REFLECTOR OR MAK WITH THE STANDARD, TYPICAL COATINGS. THE DIAGONAL IS EXTREMELY WELL MADE AND TOLERANCES KEEP THE OPTICAL AXIS TRUE AS COLLIMATION PROVES. THIS IS A LOT OF MIRROR FITTED INTO A HIGH QUALITY DIAGONAL USING COMPRESSION RINGS. THE INCLUDED 1 1/4" EYEPIECE ADAPTER ALSO USES A COMPRESSION RING TO PREVENT MARRING OF YOUR EYEPIECES. IF I HAD TO CHOSE FROM ANY MIRROR DIAGONAL ON THE MARKET, I WOULD CHOSE GSO, MADE IN TAIWAN, NOT BY SYNTA ON MAINLAND CHINA, WHO MASS MARKETS SO MANY MEDIOCRE SCOPES, MOUNTS AND OTHER OPTICAL PRODUCTS. I'VE HAD TO SEND WAY TOO MANY OF THOSE BACK TO OTHER VENDORS. BUY AGENA AND GSO AND YOU'LL BE VERY HAPPY NOT ONLY WITH THE PRODUCT BUT WITH FRIENDLY AND PROFESSIONAL SUPPORT AS WELL!!

This review was provided courtesy of AgenaAstro.com

5.0 Diamond in the rough

A very good quality diagonal with two unique and advantageous features - a zero stack height 1.25" eyepiece adapter, and a non-tapered nosepiece without safety grooves. Excellent value!

This review was provided courtesy of AgenaAstro.com

5.0 Great service

Got the diagonal. Perfect shape and shipped fast. I'm happy!

This review was provided courtesy of AgenaAstro.com

4.0 Inexpensive used on a ST80

Inexpensive used on a ST80 with 2" GSO focuser.

This review was provided courtesy of AgenaAstro.com

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.

This review was provided courtesy of AgenaAstro.com

5.0 Low Cost High Quality

GSO = Guan Sheng Optical, a Chinese optical factory that makes telescopes and accessories for all the big names, Meade, Celestron, Stellarvue etc. This diagonal is a generic version of a big name, same quality, different logo and paint job. The bottom line is this diagonal is excellent at a lower price point.

This review was provided courtesy of AgenaAstro.com

5.0 Great star diagonal

Robust quality product at a good price. Works well with my Baader Hyperion zoom eyepiece. Great service with Agena.

This review was provided courtesy of AgenaAstro.com

5.0 Best upgrade since...sliced bread

Now we can see forever!

This review was provided courtesy of AgenaAstro.com

5.0 GSO 2" 90 Diagonal

Beautiful to use and beautiful look at.
Highly recommended.
AgenaAstro delivers promptly.
Their service is second to none.

This review was provided courtesy of AgenaAstro.com

5.0 Agena GSO 2" Dielectric Diagonal

Excellent materials and workmanship - a fine 2" diagonal - worth every penny. No need to pay more. Compression in both 2" and 1.25". Highly recommended.

This review was provided courtesy of AgenaAstro.com

5.0 Excellent!

Bought this to replace the OEM 1.25" diagonal on a Celestron XLT AZ 102. This is a very solid diagonal, works perfectly. GSO makes great stuff.

This review was provided courtesy of AgenaAstro.com

5.0 Very Satisfied with purchase

This is a well manufactured diagonal with a good quality mirror. I needed a diagonal with a straight barrel to function well with a focuser that has a clamping ring (instead of set screws). This works perfectly.

True - there are higher quality diagonals available, if you're after the ultimate image, but those cost 4x or more than the GSO.

This review was provided courtesy of AgenaAstro.com

5.0 Well priced diagonal

Well priced with nice build quality. View looks excellent. 2" to 1.25" adapter is zero light path length which may be important for people using eyepieces like the Baader zoom which requires some additional in-focus as compared to most eyepieces.

This review was provided courtesy of AgenaAstro.com

5.0 Great value

I got this for my 4.7 wide field refractor and it really improved the amount of light taken in by the scope through the eyepieces, even with 1.25 inch eye pieces. It's night and day.

This review was provided courtesy of AgenaAstro.com

5.0 Impressive quality

I've developed an affinity for GSO products, this diagonal is high quality, solid and great value for the money. Precision machined and solid, nice storage case too. Purchased for optical viewing through a RC-6 (like a refractor) also purchased a SCT Barrel from 2" GSO SCT Diagonals so I could use on a Meade 8 SCT whenever I wanted. Good folks at Agena-Astro always get products out lightning fast too.

This review was provided courtesy of AgenaAstro.com

5.0 Top Notch

Quality Lenses,Accurate,Strong Construction

This Diagonal is extremely well built and designed. It replaced the diagonal that came with my scope and it complements it perfectly and provides brighter and clearer views. I would purchase it again and I am now curious to try other GSO products.

This review was provided courtesy of AgenaAstro.com

4.0 Quality optics at an affordable price

Excellent Compatibility,Robust Contruction,Excellent Optics,Quality Fit Finish

This achieves an excellent upgrade to brightness and viewing quality when fitted to most entry level telescopes and won't break the bank.

This review was provided courtesy of AgenaAstro.com

5.0 Quality product, Not lightweight

Accurate,Strong Construction,Gives Maximum Fov

Need To Re-balance,Heavy

Solidly built. When using with an eyepiece that is also heavy, you may need to re-balance your scope. That goes double if you throw in a 2" barlow.

I'm still "om the fence" about whether 2" eyepieces or an F 6.3 focal reducer is the best way to get a wide field view in a C-8.

This review was provided courtesy of AgenaAstro.com

5.0 Significant Upgrade from Stock

Strong Construction

Heavy

This was purchased to replace a dropped, "came with the tube", diagonal. It is very well built. It is also significantly brighter than the part it replaced. After using it for a couple of months I purchased the 1 1/4" version for another scope.

This review was provided courtesy of AgenaAstro.com

5.0 Excellent Quality

Strong Construction,Easy to Use,Accurate

None

The CNC machine work on this diagonal is exceptional. The mirror is literally flawless.

I installed this diagonal on a 120mm achromatic refractor that I was installing a GSO focuser. Form, fit, and function characteristics are beyond any expectations.

The 1.25" adapter supplied with the diagonal also fits tightly and centers the eyepiece barrel perfectly.

This review was provided courtesy of AgenaAstro.com

5.0 I like it

The GSO 2" diagonal is working great for me. I use it on a 127mm diameter 1200mm focal length refractor. I took a look at Jupiter at 240x. I could see the Red Spot and detail in the belts. Ganymede was a tiny disk. The diagonal is optically fine in my system. The tube that fits into the focuser is threaded and is a perfect fit for my 2" Fringe Killer filter. At low power, there is no vignetting with my 40mm Erfle. The price was right.

This review was provided courtesy of AgenaAstro.com

5.0 GSO 2" 90-deg Diagonal

Great fit,Easy to Use,Very Nice Finish,Strong Construction,Sharp views

Heavy

This GSO 2" 90-degree diagonal replaced the stock 45-degree diagonal that came on my Celestron 102GT refractor. The GSO has a dielectric mirror as opposed to a prism. I use this diagonal with a Baader Zoom eyepiece and get very sharp views with great contrast. Construction and finish of the GSO 2" diagonal is very good.

This review was provided courtesy of AgenaAstro.com

5.0 Built like a tank!

Strong Construction

The quality of this diagonal is obvious at first sight. The aluminum body is machined from a single block, and is nicely anodized. The nosepiece fits my visual back perfect, with no slop. The mirror, as far as I can tell, is perfect.

This review was provided courtesy of AgenaAstro.com

5.0 Very well built and solid

Strong Construction

The GSO 2" diagonal is the latest addition to my setup. I purchased it along with the GSO crayford focuser for my Celestron C6R-GT and it's almost like having a new scope! Very well built and heavy to help balance my tube assembly. View was very bright and crisp with no distortion I could see. I see no reason this shouldn't give me years of pleasure regardless of what scope I may buy.

This review was provided courtesy of AgenaAstro.com

5.0 Beautifully made

Well Made,Easy to Use,Accurate,Quality Lenses,Strong Construction

None

I was immediately impressed by the high quality CNC work and finish of the diagonal. I'm waiting on my new telescope to arrive and I have the diagonal on my desk so I can pick it up now and then just to admire it. The lenses were crystal clear and the diagonal itself has a great feel to it. The price point was below what I would expect to pay for such a fine product. I can't wait to try it out. This is my first 2" diagonal being used to the 1.25" size and weight. Be advised the 2" has some weight to it. I highly recommend this product and GSO as a manufacturer specifically. Agena was responsive to a question I had and shipped the product out promptly.

This review was provided courtesy of AgenaAstro.com

5.0 Solid Performer

Strong Construction,Easy to Use

This diagonal is a great upgrade/replacement for your telescope. It is heavy duty, with solid construction. The 1.25 adapter has a compression ring, which is a nice feature to have. Solid product.

This review was provided courtesy of AgenaAstro.com

5.0 This is a great diagonal

Great Value,Good quality

I bought one of these a couple years ago for my 8" SCT and when I needed a 2" diagonal for my 100mm refractor it was a no brainier to get another. The best bargain in 2" diagonals.

This review was provided courtesy of AgenaAstro.com

5.0 GSO 2" 90 Degree Dielectric Diagnol

Strong Construction,Quality Lenses,Accurate

At night, I used it with conjunction with my premium eyepiece and with ES127AR and Meade 152AR. Now keep in mind that even the BEST diagonal will not give you a crisp, bright and free of aberration and loss of light if your scope is not collimated and aligned properly. Over all; this is a phenomenal diagonal and sure it may rethink those who had been dominated in the telescope market

This review was provided courtesy of AgenaAstro.com

5.0 Very Nice 2" Diagonal

High quality construction

None

Excellent quality, excellent coatings on mirror. Machined tolerances are top notch. Highly recommended.

This review was provided courtesy of AgenaAstro.com

5.0 Excellent diagonal at a winning price

Solid build,Excellent contrast,Low price,Excellent image brightnes,Excellent surface accurac

Thin plastic end caps,Unanodized insert tube

This 2" 99% reflectivity dielectric mirror diagonal from GSO is a great performer. I compared it head to head with a buddy's William Optics 2" 99% dielectric diagonal using my Sky90. The William Optics diagonal is touted to have a 1/10th wave substrate surface accuracy while the GSO diagonal is advertised with 1/12th wave substrate surface accuracy. Sometimes if the multilayer dielectric coatings are not evenly applied to the surface the advertised surface accuracies will no longer be valid. Happily it appears that both WO and GSO use the latest multilayer dielectric coatings application technology which does not impact the surface accuracy to any great extent. This is clear in the star testing done on my optically superb Sky90. Comparing the star test with and without these diagonals, the star test remained identical. Hence these diagonals clearly do not introduce any additional optical errors in the light path.

Views of DSOs using either diagonal and a quality Panoptic were identical. For example, I easily detected M76 with direct vision under Mag 5.5 skies using either diagonal and the 15 mm Panoptic using the Sky90. When a Lumicon OIII filter was used, the extent of the faint "wings" was the same using either diagonal. Image contrast provided by either diagonal appears to be identical. For example, the knot of dark dust that juts into the Trapezium in the Orion nebula shows identical wispiness and mottling using either diagonal under the same Mag 5.5 skies using a 7mm Nagler. Image brightness provided by either diagonal is the same. For example, using the 7 mm Nagler, M15 resolved almost 50% of the way into the core using either diagonal and the globular had identical brightness graduation beginning from the center and moving out. In addition, the angular extent of this somewhat compact globular was identical using either diagonal. The build quality of this diagonal is quite good but the William Optics just has a slightly more solid feel to it. In addition, I did notice that the focuser insert tube on the GSO was not anodized black unlike on the William Optics. Mind you, these are mere cosmetic trifles only. Performance of either diagonal was identical and so I'd heartily recommend this diagonal as the better bang-for-your-buck.

This review was provided courtesy of AgenaAstro.com

5.0 Great diagonal

Great quality,Sharp views,Nice features

None

I got this to compare against the Astro-Physics Maxbright. In short, I kept the GSO and sold the Maxbright. The GSO had excellent fit and finish, and it has views which were every bit as sharp and bright as the Maxbright. The GSO also has the ability to remove the nose piece and replace it with a version which can screw onto SCT threads which is a nice feature. The GSO also comes in a nice foam-lined box with end caps and a 1-1/4 to 2-inch adapter which, because of its design, is a 0-height adapter...in other words it does not raise the height of the eyepiece at all because the part that holds the 1-1/4-inch eyepiece is actually recessed a bit. This is a neat feature. This is a great quality diagonal with tough dielectric coatings that is 1/3 the price of the Maxbright. The GSO is definitely recommended.

This review was provided courtesy of AgenaAstro.com