TV-76 3" (76mm) f/6.3 Evergreen Tube/Black Trim APO

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The TV-76 uses a 3” (76mm) true apochromatic doublet lens using an SD (special dispersion) glass element. Thanks to this special low chromatic dispersion glass, chromatic aberration is essentially non-existent with the TV-76, even at magnifications over the theoretical limit of 60x per inch of aperture.

This evergreen and black TV-76 optical tube has a 2” rack and pinion focuser with a non-marring brass clamp ring that holds 2” star diagonals and accessories securely in place. It comes in a soft foam-fitted Cordura-style nylon carrying case that has cutouts for six eyepieces in addition to the scope. A retractable lens shade improves daytime contrast when viewing at low sun angles and protects against dewing at night. A thread-in metal dust cap protects the optics from damage while stored or traveling.

The scope’s standard equipment split-ring tube holder/tripod adapter allows you to mount it on any optional sturdy photo tripod for casual use, or on an optional equatorial or altazimuth mount (such as the TeleVue Tele-Pod and Panoramic mounts) for more serious observing. The split ring design of the tube holder allows the TV-76 to be moved fore and aft in the adapter to balance the weight of camera or accessories.

The TV-76 comes with a 2” Everbrite dielectric coated mirror diagonal that has a full 99% reflectivity, and higher planetary/lunar contrast than conventional aluminum diagonals. The 2” diagonal lets you use long focal length 2” eyepieces for low power rich field observing. It also has an adapter for using 1.25” eyepieces. Both diagonal and adapter use non-marring brass clamp rings to hold eyepieces and accessories in place.

The standard equipment eyepiece is a 20mm 1.25” TeleVue Plössl. This premium eyepiece provides a magnification of 24x, with a field of view more than four times as wide as the full Moon. It has a good 3.2mm exit pupil for deep space observing, one that’s capable of revealing literally hundreds of nebulas, galaxies, and star clusters. Put in an optional lower power eyepiece and the TV-76 becomes a true rich field telescope, capable of scanning wide scenic vistas by day and revealing multitudes of large, faint deep space objects by night. With an optional 1.25” 40mm TeleVue Plössl (12x, with a 3.5 degree field), or a 2” 35mm TeleVue Panoptic (14x, with a 4.7 degree field that’s wide and flat to the very edges), the TV-76 is not only a superlative rich field scope, but it is its own best finderscope, as well.

It’s also excellent as a terrestrial spotting scope for vacations, birding, or nature studies. In addition, optional camera adapters turn the TV-76 into excellent 480mm (9.6x) f/6.3 telephoto lens for terrestrial and lunar photography.

Optional shorter focal length eyepieces and/or Barlow lenses will provide high powers to let you examine details in the storm belts of Jupiter, the rings of Saturn, the mountains of the Moon, and much more. And the resolution of those details will be crisp and detailed, often visibly superior to larger telescopes more easily affected by atmospheric conditions.

Here are some excerpts about the scope’s optical performance from a review of the TV-76 in the September 2002 Astronomy magazine. Concerning double stars and planets, the magazine said “In-and-out-of-focus star tests, star diffraction patterns, and the ability to resolve various double stars reveal the TV 76’s top-notch optical quality. If the atmospheric seeing permits, the TV 76 easily resolves doubles with a separation at the theoretical limit of a 76mm aperture scope of 1.6 arc-seconds. Planetary views in the TV 76 are best seen through the higher magnifications offered by the 3mm—6mm Nagler Zoom eyepiece. Jupiter and Saturn reveal subtle color variations and both planets’ retinues of moons are visible. When the seeing conditions are good, the TV 76 reveals atmospheric belts on Jupiter beyond the two prominent equatorial belts, as well as Cassini’s division in the rings of Saturn.” About the Moon, the magazine said “The moon seen through the TV 76 is tack-sharp at all magnifications, with no glare or false colors in the view. Stars near the bright limb of the moon are easily picked out because of the absence of glare in the telescope.”

While the 76mm aperture of the TV-76 might make it more a “light cup,” rather than the more familiar Dobsonian reflector “light bucket,” Astronomy had the following to say about the TV-76 performance outside the solar system. “When used as a rich-field scope for deep-sky viewing, the TV 76 excels. With a long focus eyepiece in the 2-inch diagonal, the scope offers impressive views of “showpiece” objects that are too large in angular diameter to fit into the smaller fields of view of larger telescopes. Under a dark Arizona sky, the Andromeda Galaxy (M31) shows its full 3° extent, including its central dust lanes and two companion galaxies – M32 and NGC 205. Dozens of stars in the Pleiades cluster look like sparkling diamonds scattered on black velvet.

“The TV 76 ‘light cup’ provides surprisingly good views of large nebular objects. I threaded Lumicon’s UHC (Ultra High Contrast) filter into the ‘pineapple’ eyepiece (i.e. the Nagler 31mm Type 5) and it yielded clear views of the full extents of the North America Nebula and of the Cygnus Loop, a supernova remnant in the summer Milky Way.” All in all, the Astronomy review called the TeleVue TV-76 “a fine choice for observers who require both high quality and extreme portability.”

An optional TeleVue Qwik-Point non-magnifying illuminated finder quickly attaches to the scope’s mounting ring. The Qwik-Point seems to project a small red ball of light wherever the scope is aimed, day or night, making it easy to align it on distant objects.

There are few optical systems that combine into one very compact body the ability to be customized into a serious astronomical telescope with true apochromatic optics, a terrestrial spotting scope, and a top-quality telephoto lens – but the TV-76 does it all beautifully. Whether you want to observe the skies from your back yard on the spur of the moment, or travel round the world with a very portable telescope that will reveal and photograph everything nearby and distant, you’ll find it hard to beat this truly exceptional TeleVue refractor.

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.
160x
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).

11.9
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.

480mm
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/6.3
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.

1.52 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.
3"
Weight:
The weight of this product.
7 lbs.
Heaviest Single Component:
The weight of the heaviest component in this package.
5.1 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:
Fair
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 . . .
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Visual Accessories
Eyepieces (3)
11mm Plössl
by TeleVue
Quantity:  
$100.00
$94.00 On Sale 
40mm Plössl
by TeleVue
Quantity:  
$150.00
$140.00 On Sale 
3mm to 6mm Nagler 1.25" zoom eyepiece
by TeleVue
Quantity:  
$425.00
$389.00 On Sale 
  • Evergreen body with black trim
  • 3" ED glass apo optics
  • Tube ring/photo tripod adapter
  • 2" rack and pinion focuser with brass clamp ring accessory holder
  • 2" Everbrite dielectric coated 99% reflectivity mirror diagonal and 1.25" accessory adapter, both with brass clamp ring accessory holders
  • 1.25" 20mm Plössl eyepiece (24x)
  • Self-storing metal dew cap
  • Thread-in metal objective lens cover
  • Soft fitted carrying case with shoulder strap.
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TeleVue - TV-76 3" (76mm) f/6.3 evergreen tube/black trim apo

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TeleVue - TV-76 3" (76mm) f/6.3 evergreen tube/black trim apoImage showing the retractable dew shield extended.Image showing the large focusing knobs and the 2” focuser.
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This 76mm TeleVue refractor has superlative apo optics that you can take anywhere in the world (even your own backyard) to enjoy with a minimum of fuss and a maximum of visual enjoyment . . .





. . . our 34th year