NP-101 4" f/5.4 Nagler-Petzval ivory tube/black trim apo, with accessories

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This TeleVue refractor tube has:

• 101mm f/5.4 four-element Nagler-Petzval apochromatic optical system
• 2” rack and pinion focuser with 2” accessory adapter
• 2” Everbrite dielectric star diagonal with 1.25” eyepiece adapter
• retractable dew shield
• fitted hard case
• state-of-the-art visual and imaging capabilities
• 5-year warranty

The TeleVue NP-101 refractor is TeleVue's closest approach yet to the holy grail of the "perfect" portable multi-purpose photo/visual telescope. The NP-101 has snap-to-focus sharpness across even the widest true fields, and rich lunar and planetary contrast that will take your breath away. Its quality, easy set-up, and airline portability beckons your use . . . in your backyard or on the far side of the world.

TeleVue first reinterpreted the incredible design flexibility of the Petzval portrait lens into an astronomical objective over 20 years ago. They’ve been refining the design ever since. No other optical design affords the same freedom to simultaneously correct for coma, astigmatism, field curvature, secondary spectrum, spherical aberration, and spherochromatism that the Nagler-Petzval design provides.

This four-element air-spaced Nagler-Petzval system has a 101mm aperture ED doublet at the front of the scope, with a second field-flattening/aberration-correcting ED doublet within the barrel at the rear. The artful combination of materials and design gives the TeleVue NP-101 diffraction-limited performance into the furthest reaches of the visual spectrum.

For visual use, the scope’s 540mm focal length is long enough, using a 1.25” TeleVue 2.5mm Nagler eyepiece, to provide 216x for high magnification observations of the Moon, planets, and binary stars; yet it will also produce a huge 4.7° field at 17.4x, using a 2” TeleVue 31mm Nagler eyepiece, for wide field observing.

Whether you are interested in nature observing on earth, exploring the visual riches inside the solar system or deep in space, or to photography on land in the night sky, simply put an eyepiece in the NP-101, or attach a camera, and the NP101 is ready to satisfy you right out of its case.

This Telescope’s Optical and Mechanical Systems . . .

  • Nagler-Petzval apochromatic refractor optics: 4” (101mm) aperture, 540mm focal length, f/5.4 apochromatic four-element air-spaced optical system. ED (Extra-low Dispersion) glass elements in both the front and rear doublets of the system provide images that are free from spurious color and other optical aberrations.

  • Multicoated optics: Fully coated on all surfaces with multiple layers of antireflection materials for high light transmission and good contrast.

  • 2” rack and pinion focuser: The very precise and smooth focuser has a 2” non-marring brass clamp ring with two lock knobs to hold a 2” star diagonal or other visual accessories firmly in place.

  • 2” Everbrite star diagonal: The supplied 2” Everbrite mirror star diagonal has ion-deposited dielectric coatings for a very high 99% reflectivity. A non-marring brass clamp ring with two lock knobs hold 2” eyepieces firmly in place.

  • 1.25” accessory adapter: The supplied 1.25” accessory adapter can be used in directly in the 2” focuser drawtube to hold 1.25” visual and photographic accessories. It can also be used in the 2” Everbrite diagonal to allow the use of 1.25” eyepieces in the 2” diagonal. A non-marring brass clamp ring hold 1.25” eyepieces and accessories firmly in place.

  • Sliding captive dew shield: Slows the formation of dew on the lens to extend your undisturbed observing time. Also improves visual and photographic contrast by shielding the lens from off-axis ambient light (the neighbor’s yard light, moonlight, etc.) For transport, the retractable lens shade keeps the overall length of the optical tube to a manageable 26.1” without diagonal when it is retracted. A thread-in protective metal dust cover is standard.

  • Mounting ring: The underside of the supplied ring mount has three 1/4”-20 mounting holes for direct installation of the NP-101 on a TeleVue Panoramic altazimuth mount (good performance) or a TeleVue Gibraltar altazimuth mount (better performance). They also allow you to connect the NP-101 to an appropriate optional dovetail plate for mounting the scope on an equatorial mount. A batwing handle unlocks the split mounting ring to allow the 9 pound scope to be slid fore and aft within the ring to balance it under different equipment loads.

  • Finderscope mounting point: No finderscope is supplied. However, dovetail accessory mounting slots for a finderscope and other accessories (such as a piggyback camera mount) are provided on top of the scope’s ring mount.

  • Carrying case: A custom foam-fitted locking hard shell case is standard. An optional soft case for airline travel is also available.
Highest Useful Magnification:
This is the highest visual power a telescope can achieve before the image becomes too dim for useful observing (generally at about 50x to 60x per inch of telescope aperture). However, this power is very often unreachable due to turbulence in our atmosphere that makes the image too blurry and unstable to see any detail.

On nights of less-than-perfect seeing, medium to low power planetary, binary star, and globular cluster observing (at 25x to 30x per inch of aperture or less) is usually more enjoyable than fruitlessly attempting to push a telescope's magnification to its theoretical limits. Very high powers are generally best reserved for planetary observations and binary star splitting.

Small aperture telescopes can usually use more power per inch of aperture on any given night than larger telescopes, as they look through a smaller column of air and see less of the turbulence in our atmosphere. While some observers use up to 100x per inch of refractor aperture on Mars and Jupiter, the actual number of minutes they spend observing at such powers is small in relation to the number of hours they spend waiting for the atmosphere to stabilize enough for them to use such very high powers.
216x
Visual Limiting Magnitude:
This is the magnitude (or brightness) of the faintest star that can be seen with a telescope. The larger the number, the fainter the star that can be seen. An approximate formula for determining the visual limiting magnitude of a telescope is 7.5 + 5 log aperture (in cm).

This is the formula that we use with all of the telescopes we carry, so that our published specs will be consistent from aperture to aperture, from manufacturer to manufacturer. Some telescope makers may use other unspecified methods to determine the limiting magnitude, so their published figures may differ from ours.

Keep in mind that this formula does not take into account light loss within the scope, seeing conditions, the observer’s age (visual performance decreases as we get older), the telescope’s age (the reflectivity of telescope mirrors decreases as they get older), etc. The limiting magnitudes specified by manufacturers for their telescopes assume very dark skies, trained observers, and excellent atmospheric transparency – and are therefore rarely obtainable under average observing conditions. The photographic limiting magnitude is always greater than the visual (typically by two magnitudes).

12.5
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.

540mm
Focal Ratio:
This is the ‘speed’ of a telescope’s optics, found by dividing the focal length by the aperture. The smaller the f/number, the lower the magnification, the wider the field, and the brighter the image with any given eyepiece or camera.

Fast f/4 to f/5 focal ratios are generally best for lower power wide field observing and deep space photography. Slow f/11 to f/15 focal ratios are usually better suited to higher power lunar, planetary, and binary star observing and high power photography. Medium f/6 to f/10 focal ratios work well with either.

An f/5 system can photograph a nebula or other faint extended deep space object in one-fourth the time of an f/10 system, but the image will be only one-half as large. Point sources, such as stars, are recorded based on the aperture, however, rather than the focal ratio – so that the larger the aperture, the fainter the star you can see or photograph, no matter what the focal ratio.

f/5.4
Resolution:
This is the ability of a telescope to separate closely-spaced binary stars into two distinct objects, measured in seconds of arc. One arc second equals 1/3600th of a degree and is about the width of a 25-cent coin at a distance of three miles! In essence, resolution is a measure of how much detail a telescope can reveal. The resolution values on our website are derived using the Dawes’ limit formula.

Dawes’ limit only applies to point sources of light (stars). Smaller separations can be resolved in extended objects, such as the planets. For example, Cassini’s Division in the rings of Saturn (0.5 arc seconds across), was discovered using a 2.5” telescope – which has a Dawes’ limit of 1.8 arc seconds!

The ability of a telescope to resolve to Dawes’ limit is usually much more affected by seeing conditions, by the difference in brightness between the binary star components, and by the observer’s visual acuity, than it is by the optical quality of the telescope.

1.15 arc seconds
Aperture:
This is the diameter of the light-gathering main mirror or objective lens of a telescope. In general, the larger the aperture, the better the resolution and the fainter the objects you can see.
4"
Weight:
The weight of this product.
11.3 lbs.
Heaviest Single Component:
The weight of the heaviest component in this package.
9 lbs.
Telescope Type:
The optical design of a telescope.  Telescope type is classified by three primary optical designs (refractor, reflector, or catadioptric), by sub-designs of these types, or by the task they perform.
Refractor
 
Based on Astronomy magazine’s telescope "report cards", scopes of this size and type generally perform as follows . . .
Terrestrial Observation:
Observing terrestrial objects (nature studies, birding, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial observing. Scopes with apertures under 5" to 6" are generally most useful for terrestrial observing due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes. 
Yes
Lunar Observation:
Visual observation of the Moon is possible with any telescope. Larger aperture scopes will provide more detail than smaller scopes, thereby getting a higher score in this category, but may require an eyepiece filter to cut down the greater glare from the Moon's sunlit surface so small details can be seen more easily. Lunar observing is more rewarding when the Moon is waxing or waning as the changing sun angle casts constantly varying shadows to reveal craters and surface features by the hundreds.  
Great
Planetary Observation:
Very Good
Binary and Star Cluster Observation:
Very Good
Galaxy and Nebula Observation:
Good
Photography:
Yes
Terrestrial Photography:
Photographing terrestrial objects (wildlife, scenery, etc.) is usually possible only with refractor and catadioptric telescopes, and convenient only when the scope is on an altazimuth mount or photo tripod. Most reflectors cannot be used for terrestrial photography. Scopes with focal ratios of f/10 and faster and apertures under 5" to 6" are generally the most useful for terrestrial photography due to atmospheric conditions (heat waves and mirage, dust, haze, etc.) that degrade the image quality in larger scopes.
Yes
Lunar Photography:
Photography of the Moon is possible with virtually any telescope, using a 35mm camera, DSLR, or CCD-based webcam (planetary imager). While an equatorial mount with a motor drive is not strictly essential, as the exposure times will be very short, such a mount would be helpful to improve image sharpness, particularly with webcam-type cameras that take a series of exposures over time and stack them together. Reflectors may require a Barlow lens to let the camera reach focus. 
Yes
Planetary Photography:
Yes
Star Cluster / Nebula / Galaxy Photography:
Yes
Warranty:
5 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 . . .
Tele Vue NP101
TeleVue NP-101 vs. Celestron NexStar 8

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General Accessories
Telescope Carrying Cases (1)
Soft airline carry bag for NP-101 refractor
by TeleVue
Quantity:  
$155.00 
Visual Accessories
Eyepieces (3)
31mm 2" Nagler Type 5
by TeleVue
Quantity:  
$695.00
$629.00 On Sale 
2.5mm Nagler Type 6
by TeleVue
Quantity:  
$330.00
$299.00 On Sale 
16mm Nagler Type 5
by TeleVue
Quantity:  
$365.00
$349.00 On Sale 
  • Hard case 
  • 2" Everbrite star diagonal
  • 1.25" accessory adapter
  • Ring mount
  • Sliding lens shade
  • Thread-in dust cover
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TeleVue - NP-101 4" (102mm) f/5.4 Nagler-Petzval ivory tube/black trim apo, with accessories

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TeleVue - NP-101 4" (102mm) f/5.4 Nagler-Petzval ivory tube/black trim apo, with accessoriesImage showing the TeleVue NP-101 in its hard case.Image showing the TeleVue NP-101 with all supplied accessories.
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Our Product #: NP101
Manufacturer Product #: NPF-4056
Price: $3,895.00  FREE ground shipping - Click for more info
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The NP101 is TeleVue's closest approach yet to the holy grail of the "perfect" multi-purpose photo/visual telescope . . .





. . . our 34th year