Excellent optics and build quality

The Leica 20xw eyepiece is manufactured by Leica for use on their Televid scopes. It magnifies 16x and 20x on the 62mm and 77mm scopes respectively. However, it may be used on any telescope with a standard 1.25" focus tube with the aid of a simple and inexpensive adaptor available from Leica.

Build
The eyepiece is surprisingly large and though weighing only 246g it feels quite heavy in the hand. The housing is made from anodised aluminium alloy with a matt black finish and appears to be machined to a very high quality. It attaches to the scope by means of a bayonet, and is held in place by friction (applied by a spring clip) rather than by a lock. On my scope it is held firmly with no danger that it will work loose. There is a pull out eye tube with a soft rubber covering for comfort. The eye tube only has two positions i.e. in and out. On my sample it stays in place without problems although I do wonder how it will fare over several years of use.

The outer lens elements are coated with a hard transparent mineral - quartz - to protect against scratches.

Leica claim that the eyepiece is waterproof when mounted on a Leica Televid telescope.

Optics
(Note: The following comments apply to the eyepiece used on the Leica APO 77 Televid.) The optics are superb. The real field of view is 3.45 degress with a huge apparent field of view of almost 70 degrees giving a wonderful 'walk in' feel to images. Eye relief is huge. I wear eyeglasses and had no trouble seeing the entire field of view. I was though a little concerned that I might scratch the eyepiece lens with my eyeglasses as it is so large: this seems to be a problem with all high quality eyepieces.

When used in daylight for watching birds the eyepiece gives an image that is beautifully sharp and contrasty with huge depth of field over most of the field even near the field edges. There is though noticeable curvature of field about 80% out from the field centre though it is not significant due to the huge field of view. I sometimes noticed a trace of chromatic aberration at the field edges but I consider it to be of no signficance. I saw no flare or ghosting.

On the night sky the images are superb. The stars are pin points against a jet black sky over the entire field. Deep sky objects such as the globular cluster M13 and the galaxies M81 and M82 are clearly rendered as hazy blobs on a black background without averted vision indicating excellent image contrast. On very bright objects such as Jupiter and Venus I noticed a trace of chromatic abberation and a bit of scatter, but nothing to worry about.

Summary
A superb eyepiece and highly recommended. I am told that amateur astronomers have a high regard for this eyepiece and often use it on non-Leica telescopes.

I would not recommend this as the main eyepiece for bird watching due to the low magnification. For that purpose the 32xw and zoom eyepieces are perhaps better suited. However, the large depth of field makes for a very relaxing view, and I would certainly recommend it as a second eyepiece, or for low light work.

I strongly recommend this eyepiece for amateur astronomy on a Leica 77mm APO Televid. It is capable of delivering superb wide field views.

Value for money
In the UK the eyepiece is very competively priced when compared with similar products from other manufacturers such as Swarovski and Nikon.

Specification
NB: The following apply when the eyepiece is used on the Leica 77mm Televid scopes.

20xw
Focal length: 22mm
Field of view: 60m at 1000 m
Angle of view: 3.45 degrees
Apparent Angle of view: 69 degrees
Eye relief: 20mm
Length: 68mm
Weight: 246g