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TeleVue 31mm Nagler Type 5


For many years the 31mm reigned as THE choice for a low-power eyepiece in large aperture Dobsonian telescopes with focal ratios f/4.5 or higher. The combination of a 31mm Nagler with f/4.5 optics yields the maximum useful exit people for most people. Many of today's large aperture Dobsonians feature even faster focal ratios, which favor alternatives such as the 26mm Nagler or 21mm Ethos.

Owners of Refractors and Schmidt-Cassegrains will simply love the magnificent field of view offered up by this eyepiece. It offers both a wider true field and a larger image scale than the venerable 35mm Panoptic, which is a truly difficult combination to beat!


Item #ProductStock StatusPriceShipping
EN5-31.0TeleVue 31mm Nagler Type 5
In Stock - Ships Same Day (business days) This is "live" inventory data. If it says in stock, you can believe it.
$695.00
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Optical Specifications: TeleVue 31mm Nagler Type 5
Focal Length 31 mm
Apparent Field-of-View 82°
Eye Relief 19 mm
Physical Parameters
Weight 35.2 Ounces
Barrel Diameter 2 Inches
Eyepiece Calculator
Enter at least two of your telescope's specifications:
*Focal Length (mm):
*Aperture (mm):
Focal Ratio (f/):
Magnification:
 
True Field:
 
Exit Pupil: <p>Exit pupil represents the diameter of the column of light exiting the eyepiece. Magnification is simply the ratio of telescope aperture to exit pupil. Fox example, using a telescope with 100mm aperture and an exit pupil of 2mm yields a magnification of 50X.</p> <p>There are both upper and lower limits to the useful range of exit pupils. The typical human eye pupil dilates to a maximum of 7mm when fully dark adapted. This figure decreases with age. Using an exit pupil that is larger than this upper limit simply spills the light onto an area of the eye not capable of receiving data. At the opposite end of the range, a smaller exit pupil means less area on the eye is collecting data. Images brightness decreases with decreasing exit pupil. Deep space objects grow dimmer rapidly as the exit pupil falls below 1 mm. The planets also start to become noticeably dimmer when the exit pupil falls much below 0.5 mm.</p> <p>Our eyepiece calculator provides warnings and error messages based upon the value of the exit pupil. These are intended to be guidelines as opposed to hard rules. There is no harm in violating these gidelines, but your enjoyment of the telescope may be diminished if you do. </p>