ED stands for "Extra-Low Dispersion". These eyepieces use optical glass in which two of the lens elements are crafted from ED glass which is a special grade of glass that provides much superior refractive properties as compared to standard optical glass. This results in much better color correction. ED glass is often the type used in many expensive camera lenses and high-end refractor telescopes costing thousands of dollars.
Our ED-series eyepieces are available in a 1.25" barrel in 10 focal lengths (2.3, 3.8, 5.2, 7.5, 9.5, 12.5, 14, 18, 21 and 25mm). They feature a six-element lens design that provides significantly reduced chromatic aberration, high resolution and excellent sharpness without compromising image brightness. Their long 20mm eye relief means that even eyeglass wearers can take in the full 55-degree apparent wide field of view (AFOV).
All ED-series eyepieces are fully broadband multi-coated for maximum image brightness. Lens edges are blackened throughout for improved contrast. The eyepiece housing is precision machined from aluminum and clear-anodized to a lustrous finish. A rubber traction ring ensures a secure grip and a rubber eyeguard helps position your eye to block out stray light. The chrome barrel features a setscrew recess for added security. All eyepieces are parfocal and are threaded to accept standard 1.25" filters. Each eyepiece comes in a bolt case with two plastic end caps. Compare these with the ED eyepieces sold in very similar focal lengths by two of the "Big-3" telescope companies and you'll realize the savings we offer.
Aug 24, 2013
Fine but touchyPros:
Quality Lenses,Strong Construction,Lightweight,AccurateCons:
Difficult to UseComments:
I find that the views are very good, with clear and sharp stars. Good FOV using a 10" f/5 reflector, focuses well, dark background, good quality overall. The only problem I had was at times I would encounter blackouts while trying to hold my eye position and deal with neighbors light coming in from the side. Over all I am very pleased.
This review was provided courtesy of AgenaAstro.comNov 6, 2009
Quality Lenses,Accurate,Strong ConstructionCons:
I had a few eyepieces but they all had a very short eye relief and only the center 1/2 of the field of view was clear. This eyepiece works from center to the edge with a clear, sharp in-focus image. The eye relief is fantastic. This is always the first eyepiece I put in my focuser every time I go out to look at the stars. The nebulas and clusters look fantastic with this eyepiece.
This review was provided courtesy of AgenaAstro.comSep 19, 2009
Surprising quality and clarityPros:
Accurate,Quality Lenses,Strong ConstructionCons:
I am new to the hobby of astronomy. Bought a used 5 inch reflector with two eyepieces. Both are inadequate though they came from name brand manufacturers. This 21 mm eyepiece was between the two I had and after 2 nights use, one on my scope and one on another scope I am convinced this is as good as it gets till I can upgrade to a much larger scope. I am ordering a second one about 7 mm today. I have shown this eyepiece to several friends and they too will be ordering this eyepiece.
This review was provided courtesy of AgenaAstro.comSort by
Apparent Field of View 55° Barrel Size 1.25" (31.7mm) Bolt Case Included Yes - Manufacturer Supplied Bolt Case Size - Coatings Fully Broadband Multi-Coated Height (with Eye Guard) 3.9" (99mm) End Caps 2 Eye Relief by Design 20mm Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6) Focal Length 21mm Lens Elements 6 Rubber Eye Guard Yes Blackened Lens Edges Yes Manufacturer Agena AstroProducts Eyepiece Focal Length 20.1mm - 30mm Eyepiece Field of View 51 - 60 degrees Eyepiece Series Agena ED Barrel Type With safety undercut Eyepiece Weight 6.90oz (195.61g)