18mm 1.25" Paradigm Dual ED

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This Astro-Tech 18mm Paradigm Dual ED is an excellent medium to medium low power eyepiece for lunar observing, encompassing globular clusters, picking up detail in emission and reflection nebulas, etc. This 18mm focal length is a good choice for filling in the gap between the 25/26mm eyepiece that comes standard with most telescopes and a high power planetary/binary star splitting eyepiece. It is usable with any telescope type, under virtually any seeing conditions – from fair to superb. (Rain, snow, or fog might limit its usefulness, however.)

With a short focal length refractor it is a medium to low power eyepiece well suited to scanning the crowded star clouds of Sagittarius. For example, with the 430mm focal length f/6 Astro-Tech AT72ED it provides 24x, a field five times as wide as the full Moon, and a 3mm exit pupil that is excellent for rich field observing and revealing large nebulas.

It is also a good choice for medium power observing with long focal length refractors, reflectors, or catadioptric scopes. On an 8” f/10 catadioptric, for example, it yields 111x, with a 0.54° field. This is a very useful magnification for observing compact planetary nebulas and globular clusters, as well as lunar observing. Its high contrast makes observing small features along the lunar terminator a nightly delight as the terminator creeps across the face of the Moon.

The six lens/four group design and two ED (Extra-low Dispersion) glass elements of the 18mm Astro-Tech Paradigm provides all of the optical virtues described at the top of this catalog page – high contrast, a sharp and flat field from edge to edge, excellent color fidelity, and exceptionally low astigmatism and barrel distortion. It has a usable eye relief of 13mm. Combined with the twist-up eyecup design, the good eye relief makes it a sensible choice for eyeglass wearers.

This new Astro-Tech 18mm Paradigm Dual ED eyepiece will make your nightly views of the heavens sharper, clearer, and more entrancing than ever before. The Paradigm will change your mind about how much truly high-end optical performance not much money can buy.

Field of view:
The field of view (FOV) is the amount of observable world one can see at any given moment.
60°
Eye Relief:
Eye relief is the distance from the last surface of the eye lens of an eyepiece to the plane behind the eyepiece where all the light rays of the exit pupil come to a focus and the circular image is formed, sometimes called the “Ramsden Disk.” This is where your eye should be positioned to see the full field of view of the eyepiece. If you must wear glasses because of astigmatism, you’ll usually need at least 15mm of eye relief or longer if you want to see the full field of view with your glasses on.

A note on our eye relief figures: Quite often, our eye relief figures will differ from those of the manufacturer. This is because we measure the “usable” eye relief, while the manufacturers specify their usually-longer (but technically correct) “designed” eye relief.

The eye lens of the eyepiece is normally recessed below the rubber eyeguard or rubber rim of the eyepiece to keep the lens from being scratched during use. An eyepiece might have a “designed” eye relief of 15mm (and the eye relief will truly measure 15mm from the eye lens to where the image forms). However, if the eye lens is recessed 3mm below the eye guard, the Ramsden Disk forms only 12mm above the eyepiece body (the 15mm “designed” eye relief, less the 3mm of eye relief made unusable by having the eye lens recessed into the body of the eyepiece). This “usable” eye relief of 12mm (measured from the rolled-down eyeguard – the closest point you can get your eye to the eye lens – to where the image forms) is the eye relief figure we would measure and list in this website.

Why is it important to list the “usable” eye relief? For those people who don’t wear eyeglasses while observing, a few mm difference between the eye relief they expect from the manufacturer’s literature and the shorter eye relief they actually get in real life doesn’t mean a lot. They can simply move a little closer to the eyepiece to see the full field, and never realize that the eye relief is a little shorter than they expected. However, some people must wear eyeglasses while observing, because of severe astigmatism. These observers can’t move closer to the eyepiece if the eye relief is shorter than expected because their glasses get in the way. For these people, the real life “usable” eye relief is more important than the technically correct but sometimes not fully usable “designed” eye relief. We measure and list the actual usable eye relief so that people in the real world can pick the eyepieces that will work best for them.

13mm
Focal Length:
This is the length of the effective optical path of a telescopeor eyepiece (the distance from the main mirror or lens where the lightis gathered to the point where the prime focus image is formed). Focallength is typically expressed in millimeters.

The longer the focallength, the higher the magnification and the narrower the field of viewwith any given eyepiece. The shorter the focal length, the lower themagnification and the wider the field of view with the same eyepiece.

18mm
Number of optical elements:
6
Barrel Size:
The industry standard diameter, as of 2011, is 1.25" and is the most common.  Other sizes available are .965" and 2".
1.25"
Weight:
The weight of this product.
5.6 oz.
Warranty:
2 years
Reviews from Cloudy Nights (www.cloudynights.com)
These reviews have been written by astronomers just like you and posted on the Cloudy Nights astronomy forums . . .
First Look: Astro-Tech Paradigm Eyepieces

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Overall Product Rating: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics(4.75)   # of Ratings: 4   (Only registered customers can rate)

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Showing comments 1-4 of 4
1. christian on 5/25/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
Amazing eyepiece, especially considering the price. Higher contrast then expected with a neutral to cool color tone. Reminded me of a 17mm Hyperion with a smaller field and no 20mm eye relief but better edge correction. With a 3x TV Barlow makes a great planetary eyepiece too.
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2. Stephen on 5/20/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
I bought one to test in my 8", f/7 Newt and the image was so sharp, with excellent contrast, that I tried it on another, smaller f/6 scope. Same results. I now own 5 different FL Paradigms and they are my "Go-To" eyepieces in all scopes of f/6 or longer. The edge sharpness is as good as center-of-field and the 60* AFOV is a big plus in any Dob. Eye relief on all Paradigms is good so I can avoid spending big $$ on expensive LER eyepieces.

I have "Big-Brand" eyepieces of $200+ each, and still prefer the Paradigms. The price is WAY under what you get in performance.
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3. alvaro on 5/1/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
This is my first Paradigm, which I use with a 3x Barlow for planetary afocal astrophotography. Also, in combination with 32 mm Plossl is my go to piece for DSO's, which I am just starting to do. With this the experience from using this piece, I am thinking in eventually getting the 25mm one for DSO work, and maybe use it to replace the 32mm Plossl. I would consider getting the 12 and 15 mm if they became available.

Alvaro
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4. Nate on 3/11/2013, said: AstronomicsAstronomicsAstronomicsAstronomicsAstronomics
Very nice eyepieces for the money! If you're looking for something inexpensive, but good quality, I think these are just right. The optics seem very good, the FOV is fine for most uses and the adjustable eye cup is a nice touch. I use these and the 82 degree ES eyepieces most and while the ES have a larger FOV and are nicer in some ways, these don't give up much for being so much less expensive. Nothing about them feels cheap.
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52mm x 80mm eyepiece container
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Astro-Tech 18mm Paradigm Eyepiece
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Astro-Tech - 18mm 1.25" Paradigm Dual ED

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Astro-Tech - 18mm 1.25" Paradigm Dual EDImage showing a typical Paradigm eyepiece with the twist-up eyecup in both the fully extended and fully retracted positions.
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This Astro-Tech 18mm Paradigm Dual ED is a medium to medium-low power eyepiece with high-priced performance at a price that is far from high-priced . . .





. . . our 34th year