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Agena 1.25" ED Eyepiece - 2.3mm

5.0 (1 Reviews) Read Reviews Write Review
Brand Agena AstroProducts
Part Number -

Product Info

Manufacturer Description

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.

Please note: Depending on your telescope, this eyepiece may provide magnifications that are too high! While it can be very useful for viewing the Sun, Moon, brighter planets and terrestrial objects, it is not for everyone or for common viewing conditions.

Before buying, please make sure that you are using realistic magnifications with your telescope. A good rule of thumb is that under very good conditions and with a very good telescope, the maximum power you will be able to use is about 50x of magnification per inch of telescope aperture. With average telescopes and/or average conditions, you might be limited to 30x of magnification per inch of telescope aperture. So for example, if you have a 6" telescope, under typical conditions you might typically use 6x30 = 180x of magnification, and 6x50 = 300x of magnification at best. If your telescope has a focal length of, say, 1000mm, then this eyepiece will result in a magnification of 1000 / 2.3 = 435x which is too much for this telescope.

Also, when you magnify an object, its light is spread over a larger area. Since the brightness of the object being viewed hasn't changed, this means that the image you see will be fainter. Double the magnification and the image will get 4 times fainter. This is a basic law of physics, but people often forget this and complain that the "image is not bright enough" when they increase the magnification to very high powers.

Boosting the magnification beyond the recommended maximum for your telescope aperture is not realistic. This is bound to result in image break-down, causing faint, fuzzy images, focusing difficulties, increased color around objects and general disappointment. Use the eyepiece in the right settings and with the correct expectations, and you will enjoy it.


5.0 (Based on 1 Reviews) 100% of reviewers recommended this product.
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      User Notes:
      Review by jtk28 of Rome, Italy.
      Nov 7, 2009

      5.0 Exceptional magnification


      Accurate,Quality Lenses


      Difficult To Focus


      It gives exceptional magnification also to poor instruments.

      Bottom Line: Would you recommend this item? Yes
      Was this review helpful? Yes / No

      This review was provided courtesy of AgenaAstro.com

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      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) 5.0" (128mm)
      End Caps 2
      Eye Relief by Design 20mm
      Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6)
      Focal Length 2.30mm
      Lens Elements 6
      Rubber Eye Guard Yes
      Blackened Lens Edges Yes
      Manufacturer Agena AstroProducts
      Eyepiece Focal Length 5mm and Under
      Eyepiece Field of View 51 - 60 degrees
      Eyepiece Series Agena ED
      Barrel Type With safety undercut
      Eyepiece Weight 7oz (198.45g)