Explore Scientific 100 Series 2'' Eyepieces
Choose: 5.5mm (2Choose: 9mm (2Choose: 14mm (2
Choose: 20mm (2Choose: 25mm (2Choose: 30mm (Note: 3

Explore Scientific 100 Series 2" Eyepieces

£258.00✓ 2 year warranty


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Explore Scientific 100 20mm 2" Eyepiece

£423.00 £373.00

About this product

Model:  es_100_9mm
Part Number:  0218409

The Explore Scientific 100° series are hyper-wide-angle (for want of a better word) eyepieces that offer a fully immersive viewing experience. You might even forget there is an eyepiece between you and the universe! 

A good choice for use with all telescopes types with ratios f5 and higher but they work especially well with Dobsonians because the huge 100° FOV also makes targets easier to locate and, for non-driven telescopes, the target stays in the FOV for a long time before the telescope needs repointing. 

The hyper-wide FOV also makes it easier to observe using ‘averted vision’ which involves not looking directly at the object, but looking a little off to the side, while continuing to concentrate on the object. Doing so places the object on a part of your eye that is more sensitive to light. This technique is most useful when observing large faint nebulae and star clusters. 

Exotic glass lenses (8 or 9, depending on the focal length) fabricated from combinations of Dense Crown, Light Crown, Dense Flint and Lanthanum with multiple anti-reflection coatings on all air-to-glass surfaces provide bright, high contrast flat-field views. Blackened lens edges and internal baffling also enhance contrast and minimise ghosting from internal reflections. 

Sealed waterproof construction and an Argon gas-purged interior protect the eyepiece from rain or dew and and eliminate internal condensation to ensure the optics remain pristine. 

Foldable rubber eyecup and long eye-relief make them a good choice for use with eyeglasses and a tapered nosepiece provides peace of mind because the eyepiece is less likely to fall out of the focuser if the lock-screw loosens. 

Threaded to accept 2" filters. 

NOTE: Currently the gas used when constructing the 20mm eyepiece is Nitrogen, not Argon. The eyepiece design and performance is the same, whichever gas is used. 


  • Hyper-wide-angle 100 degree Apparent Field Of View
  • Premium grade optical glass
  • All surfaces fully multicoated for maximum light transmission
  • Lens edges and internal metal surface are blackened to maximise contrast and reduce ghosting
  • Long eye-relief (good for eyeglass wearers)
  • Foldable rubber eyecups
  • Tapered 2" barrel for extra security

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Eyepiece Field of View Simulator


Product Code021840502184090218414021842002184250218430
Eye Relief11.6mm12.5mm14.5mm14.5mm14.5mm19mm
Field Stop Diameter9.6mm15.7mm24.4mm34.8mm41mm52.2mm
Barrel Size2” / 50.8mm2” / 50.8mm2” / 50.8mm2” / 50.8mm2” / 50.8mm3” / 76.2mm
Barrel Length31.5mm31mm39.5mm39mm42.7mm40mm
Lens Groups666676
Height (From End of Barrel)149mm120mm123.5mm122.5mm139.6mm150mm

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