Agena 1.25" Starguider Dual ED Eyepiece - 25mm

Our Price: $60.00
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Our Product ID: E-AG-SGED25
Manufacturer SKU: E-AG-SGED25
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Agena 1.25" Starguider Dual ED Eyepiece - 25mm

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  • Agena 1.25" Starguider Dual ED Eyepiece - 25mm
  • Agena 1.25" Starguider Dual ED Eyepiece - 25mm

Quick Overview

  • The Agena StarGuider Dual ED eyepieces feature high contrast, 2 element ED glass
  • Wide 60 degree Field of View (FOV) in 5mm to 25mm focal lengths
  • Exceptional at nearly eliminating lateral color aberration and light scatter while retaining excellent sharpness, contrast and definition
  • 5 or 6 lenses in up to 4 groups; comfortable 16-20mm eye relief
  • Perform as well as other, more expensive Orthoscopic and Plossl eyepieces
  • Excellent fit and finish with fully multicoated lenses and flat black anodized internal baffles and field stop
  • Rubberized body with retractable eyecups for optimum adjustment of eye relief
  • 1.25" barrel with filter thread

Product Details

With a true flat field and two high quality ED glass elements of different glass types, the new Agena StarGuider Dual ED eyepieces are characterized by a significantly high contrast image. These 1.25" fully multicoated (FMC) eyepieces give maximum detail and definition across the entire 60 degree field of view (FOV). This feature is especially useful for telescopes without tracking capability where the object drifts across the field of view during observation. A great value, these eyepieces are exceptional at nearly eliminating lateral color aberration and light scatter often associated with more expensive eyepieces that are better suited for deep space objects.

The eyepieces are parfocal, minimizing the amount of refocusing needed when switching from eyepiece to eyepiece within the series.

Agena Dual ED Eyepieces vs. More Expensive Eyepieces:

Premium (and costly!) eyepieces that have similar wide fields of view need many exotic glass elements to achieve that wide field of view - as many as 9 lenses or more. More lenses mean more cost and more glass, which attenuates the amount of light you see. That also means there are more air-to-glass surfaces that can scatter light - reducing contrast and sometimes causing multiple reflections (ghosting) when viewing very bright objects such as the Moon and planets. Extra lenses can also mean compromises in the overall design that can often lead to other issues.

One such issue of all that glass is lateral color aberration. This results when different wavelengths (colors) of light pass through the eyepieces focal plane at different points and appear as a cloud of false color around bright objects. Another issue is light scatter seen as a distracting halo or glow around bright objects. This can also reduce contrast. Light scatter and lateral color are rarely seen in very wide field eyepieces when observing faint deep sky objects, but they become very apparent when viewing lunar, planetary, and double star objects. These objects don't need an extra-wide field of view to see small details and subtle contrast differences. Our 60 degree eyepieces provide high contrast, no scattered light, and the highest possible definition.

Agena Eyepieces - Rooted in Solid Design:

Orthoscopic and Plossl eyepieces have traditionally been the designs of choice for lunar, planetary, and binary star/star cluster observations. Their low number of lenses (typically four) and air-to-glass surfaces give better contrast and definition than the more exotic extra wide field eyepieces. A high quality orthoscopic or Plossl eyepiece on a good telescope gives views of Mars, Jupiter, and Saturn that can be breathtaking. But even these designs can be improved upon for lunar and planetary use.

Long Eye Relief - Up To 20mm!

Agena's StarGuider Dual ED eyepieces are the first long eye relief eyepieces with a comfortably wide field for planetary observing that also give the sharpness, contrast, and lack of lateral color and light scatter of the best orthoscopic and Plossl designs. What they don't have is the limited eye relief and restricted fields. Our eyepiece eye relief averages around 18mm and is as much as 20mm in the 25mm focal length model. Even the 5mm eyepiece has almost 16mm of eye relief! Experienced observers will truly appreciate such generous eye relief at significant magnifications.

The nicely machined body is rubberized and scalloped grooves around the circumference at the top provide a secure grip in all conditions.

Sharpness, Great Contrast and Flat Field of View:

With up to six lens elements in this unique design, these eyepieces are fully internally baffled and all internal spacers have antireflection microbaffles on their edges with flat black anodizing to reduce reflections. The field stop also has microbaffles in its edge to reduce off-axis flaring and produce a sharply delineated field edge. Every air to glass surface is broadband multicoated for peak light transmission and outstanding contrast on subtle lunar and planetary detail. The lens edges are blackened to eliminate internal reflections.

The eyepieces have a twist-up eyecup that can be raised or lowered as much as 11mm to provide the eye relief you find most comfortable. Spherical aberration of the exit pupil is well controlled, so there are no serious blackouts or kidney-bean effects if you move your eye slightly off the axis. Dust covers are provided for both ends of each eyepiece. A groove is machined into the nose piece barrel to ensure the eyepiece is less likely to fall out of the diagonal or focuser if the capture screw becomes accidentally loose.

Technical data:

  • Focal length: Available in focal lengths of 5mm, 8mm, 12mm, 15mm, 18mm and 25mm
  • 1.25" with filter thread
  • Field of view: 60°
  • Fully multi-coated on each glass/air surface
Eyepiece Series Starguider ED
Focal Length 25mm
Barrel Size 1.25" (31.7mm)
Apparent Field of View (Mfg Specified) 60°
Eye Relief (Designed) 20mm
Filter Threads Standard 1.25" Filter Thread (M28.5 x 0.6)
Coatings Fully Multi-Coated
Lens Elements 5
Lens Groups 3
Blackened Lens Edges Yes
Barrel Type With safety undercut
Protective Plastic Storage Container Yes - Free Agena Eyepiece Container
Protective Plastic Storage Container Size Agena 52x80mm
End Caps 2
Rubber Eye Guard Yes (Twist-Up Eyecup)
Weight 5.9 oz / 167 g
Country of Manufacture China

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