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This 9mm to 27mm Astro-Tech zoom eyepiece is a fantastic choice for astronomers of every experience level.

This Astro-Tech 9mm to 27mm zoom eyepiece is a perfect size and focal lenght range to work with virtually as well as fit neatly into your current eyepiece assortment.  The black anodized 1.25" barrel is threaded for filters so it is really a nearly complete eyepiece collection that fits in just one hand.  It has a variable focal length range of 9mm to 27mm.  Its apparent field of view ranges will change from 40° to 60° depending on the focal length you choose on the zoom.  The higher the magnification, the narrower the field of view.

The usable eye relief is 15mm. This figure should allow minimal to no vignetting the field of view for those who must wear eyeglasses while observing due to astigmatism, particularly at the higher powers. Those who do not wear glasses will find the eye relief more than acceptable for unvignetted viewing, particularly when the rubber-rimmed twist-up eyecup is extended to block out ambient light and position the eye at the correct eyepoint.

The eyepiece barrel has a series of focal lengths on the barrel of the eyepeice with a marker arrow just above the numbers.  Simply twist the rubber knurled ring to the desired focal length and you are off to the races.  

All lens elements (a sophisticated 7 lens/4 group design) are fully broadband multicoated with high transmission antireflection optical coatings for maximum light transmission and contrast. High refraction/low dispersion glass elements are used for excellent color fidelity. The lens edges are also blackened to help with contrast and minimize interior reflections. Protective caps are provided for both ends of the eyepiece.

Tech Details: 

Barrel Size 1.25"
Eye Relief 15mm
Focal Length 9mm to 27mm
Number of optical elements 7
Weight 8 oz.
Warranty 1 year

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