22mm 2" Nagler Type 4

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The TeleVue 2” 22mm Nagler Type 4 replaces the 20mm Nagler Type 2, considered by many to be the finest eyepiece ever made. How do you improve on a legend? The 22mm does it by cutting the weight of the 20mm Nagler in half, doubling the eye relief, and increasing the contrast, while otherwise maintaining the superb observing experience that makes the 20mm Nagler such an observing gem.

The 22mm has TeleVue's unique "Instadjust" click-stop adjustable-height eyeguard, with a soft fold-down rubber eyecup. With the eyeguard retracted all the way, all of its very long 19mm eye relief is available for eyeglass use. The eyeguard can be raised in small and repeatable increments to position the eye of the non-eyeglass wearer the precise distance from the eyepiece to see the full field of view with maximum suppression of ambient stray light. A special doughnut-shaped removable plastic insert fits into the eyeguard to center the eye for those who have trouble positioning their eye precisely on a small exit pupil.

This eyepiece is primarily designed for no-holds-barred medium power deep space use with scopes having focal ratios down to f/4. It is marvelous for open clusters, nebulas, and globular clusters with any scope, but is particularly effective with fast f/ratio reflectors. That being said, it must also be noted that its very wide field also makes it convenient for moderate power lunar and planetary observing with Dobsonians, as you have much longer to observe before the planet drifts out of the field and the scope has to be repositioned.

Please note the weight of this eyepiece if you have a Dobsonian telescope. Its use may require some temporary rebalancing of your scope, or the use of a TeleVue #TVEQC equalizing adapter with 1.25” eyepieces to avoid balance problems.

Field of view:
The field of view (FOV) is the amount of observable world one can see at any given moment.
82°
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.

19mm
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.

22mm
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".
2"
Weight:
The weight of this product.
24 oz
Warranty:
Limited Lifetime
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General Accessories
Accessory Cases (1)
65mm x 120mm eyepiece container
by Astronomics
Quantity:  
$4.99 
Optics Cleaning Products (1)
LensPen Optics cleaning tool
by Celestron
Quantity:  
$9.95 
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Helpful Formulas
Telescope Eyepiece Formula
To calculate the magnification and approximate actual field of view of this eyepiece on your telescope, enter the focal length of your telescope below and press the "Calculate" button.

Enter your telescope's focal length: mm   



TeleVue - 22mm 2" Nagler Type 4

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TeleVue - 22mm 2" Nagler Type 4
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Our Product #: TN22
Manufacturer Product #: EN4-22.0
Price: $525.00
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The TeleVue 2” 22mm Nagler Type 4 replaces the 20mm Nagler Type 2, considered by many to be the finest eyepiece ever made . . .





. . . our 34th year