0.96" H20 Huygens 20mm telescope eyepiece

We are delighted to offer for sale this 0.96" diameter 20mm Huygens eyepiece.

We are frequently asked if we can supply eyepieces for older telescopes that have a 0.96" focuser.  While we have adapters that can let 1.25" eyepieces be used the cost sometimes seems prohibitive compared to the value of the scope.  So, we are supplying a range of 0.96" diameter eyepieces purely to meet that need.

The eyepiece is supplied in a plastic storage container.

Huygens eyepieces consist of two plano-convex lenses with the plane sides towards the eye separated by an air gap. The lenses are called the eye lens and the field lens. The focal plane is located between the two lenses. It was invented by Christiaan Huygens in the late 1660s and was the first compound (multi-lens) eyepiece. Huygens discovered that two air spaced lenses can be used to make an eyepiece with zero transverse chromatic aberration.
 

These eyepieces work well with the very long focal length telescopes (in Huygens day they were used with single element long focal length non-achromatic refracting telescopes, including very long focal length aerial telescopes). This optical design is now considered obsolete since with today's shorter focal length telescopes the eyepiece suffers from short eye relief, high image distortion, chromatic aberration, and a very narrow apparent field of view. Since these eyepieces are cheap to make they can often be found on inexpensive telescopes and microscopes.

Because Huygens eyepieces do not contain cement to hold the lens elements, telescope users sometimes use these eyepieces in the role of "solar projection", i.e. projecting an image of the Sun onto a screen. Other cemented eyepieces can be damaged by the intense, concentrated light of the Sun. (Wikipedia)

Shipping costs will only be charged once if other eyepieces from this range are purchased - make sure you "Request Total from Seller" before paying (we will refund you if you accidently pay too much).

"So yes, carry on telling people that such a small scope can be very good for a beginner – great for looking at the moon, the phase of Venus, the rings of Saturn, the moons of Jupiter and the sun.

Good news on the eyepieces that you sent! I tried them out last night by looking at Saturn, and they worked very well. As I hoped, the 20mm was good for locating it very quickly to start with (the other advantage of a small, simple scope – it is about 5 minutes from picking it up to looking at your target).

And I was also able to use the 4mm perfectly well too, even though at 150x it is above the 100x theoretical maximum for the telescope.

The image was understandably a bit dimmer but the slightly larger size was good to see." Alan Dobie - client - June 2013
 

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Skies Unlimited is the Ebay trading name of "Sky's the Limit".  Feel free to email any questions through Ebay.