PowerSeeker 70, 2.75" Altazimuth refractor

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The Celestron PowerSeeker 70mm altazimuth refractor is a good choice for a beginning astronomer who also has an eye for nature. Its sensibly-priced refractor optical system is a good way to begin your journey into the night sky, providing you with high contrast views of the Moon and planets.

The PowerSeeker optical system has quality all-glass optical components, with high transmission coatings for enhanced image brightness and clarity. The altitude slow motion control of the telescope’s mount comes in handy for keeping objects in view as they move across the night sky.

Once you have scanned your way through the solar system and the Milky Way, you can use the PowerSeeker to look at things closer to home. The altazimuth mount will let you easily track objects on the ground and allow you to get a closer look at nature and your surroundings.

The Celestron PowerSeeker 70 has a light grasp 100 times that of the sharpest eye. Combine that light grasp with its two eyepieces (a 20mm and a 4mm) and 3x Barlow lens, and you have the ability to see many, many celestial and terrestrial objects that are simply invisible to the unaided eye. It can open a whole new world to you, at a price well within reach and reason.

This PowerSeeker Telescope’s Optical System . . .


Refractor optical tube: 70mm (2.75”) aperture air-spaced two-element crown and flint glass lens. 700mm focal length f/10 all-glass optics. No plastic lenses.

Coated optics: The objective lens has antireflection coatings on all surfaces for high light transmission and good contrast.

Dew shield: A dew shield (an extension of the optical tube that’s threaded onto the front of the objective lens) slows the formation of dew on the lens in cold weather. This extends your undisturbed observing time.

Rack and pinion focuser: The 1.25” focuser has dual focusing knobs for precise image control with either hand. The large focus knobs are easy to operate, even while wearing gloves or mittens in cold weather.

Star diagonal: The 90° viewing angle 1.25” star diagonal (eyepiece holder) allows comfortable viewing when looking overhead at the sky. It has a built-in image erecting prism that provides right-reading images that show you the sky and lunar features oriented the same way you see them through binoculars or with your unaided eye.

Two eyepieces: You get a high power 1.25” 4mm (175x) eyepiece and a low power 1.25” 20mm (35x) with a 1.3° field of view (almost three times the diameter of the full Moon). Both eyepieces have antireflection coatings on their lens surfaces for sharp images and good contrast.

Barlow lens: A 1.25” 3x Barlow lens is included that triples the magnification of the two supplied eyepieces to 105x and 525x. The 525x magnification of the 4mm eyepiece/Barlow combination is realistically far beyond the scope’s usable magnification capability, however. Do not count on using that optical combination very often, if at all. A lower power eyepiece, such as a 40mm (18x; 53x with the Barlow), would provide a pair of magnifications more useful than the 525x of the 4mm and Barlow combination.

Finderscope: A low power 5x24mm finderscope attaches to the side of the optical tube. The straight-through viewing refractor finderscope provides a traditional inverted mirror-image astronomical view. If properly collimated (aligned) with the view through the main telescope, its crosshairs will help you center distant objects in the telescope so you don’t have to search for them using the narrow eyepiece field of view.

This PowerSeeker Telescope’s Mount . . .

Altazimuth mount: The no-tool setup altazimuth mount provides right/left and up/down motions. This is suitable for casual astronomical observing, and will let you easily track objects on the ground to allow you to get a closer look at nature and your surroundings. A knob at the base of the mount allows you to lock the tube in place or to adjust the drag on the scope during right/left motions. This lets you control how smoothly the mount moves as you manually push the tube left or right to follow objects moving through the sky or on the land.

Altitude slow motion control rod: A threaded rod with a knurled control nut provides vertical slow motion control while following objects across the sky. Turning the control nut moves the scope up or down in small increments. The control rod has a locking knob that can be easily released so you can quickly move the scope vertically from object to object.

Tripod: The lightweight aluminum tripod easily adjusts for standing or seated observations through the telescope. The tripod includes an accessory shelf that holds your eyepieces and Barlow.

Software: A copy of Celestron’s TheSkyX – First Light Edition CD-ROM is included for use in your PC or Mac. This planetarium and star charting software will let explore the Universe on your computer. It can print out custom star charts of the sky from its database of 10,000 celestial objects to help you find faint deep space objects by star-hopping in easy steps from a known star to the object.

Two year warranty: As an expression of Celestron’s confidence in the quality of their products, the PowerSeeker is protected by Celestron’s two-year limited warranty against flaws in materials and workmanship.


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.
140x
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).

11.7
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.

700mm
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/10
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.

1.65 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.
2.75"
Weight:
The weight of this product.
8 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.  
Fair
Planetary Observation:
Fair
Binary and Star Cluster Observation:
Poor
Galaxy and Nebula Observation:
Poor
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:
No
Star Cluster / Nebula / Galaxy Photography:
No
View Finder:
5 x 24mm
Warranty:
2 years
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Visual Accessories
Accessory Kits (1)
Visual accessory kit for Celestron PowerSeeker scopes
by Celestron
Quantity:  
$47.95
$29.95 On Sale 
  • 70mm aperture achromatic refractor optical tube with fully coated optics and 1.25" rack and pinion focuser
  • Altazimuth mount with manual slow-motion control in altitude and locks on both axes
  • 4mm (175X) and 20mm (35X) eyepieces
  • 90° 1.25” erect image star diagonal
  • 3x 1.25” Barlow lens
  • 5 x 24mm straight-through finderscope
  • Operating instructions
  • TheSkyX CD-ROM software
  • Adjustable height aluminum tripod with accessory tray.
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PowerSeeker 70, 2.75" Altazimuth refractor

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PowerSeeker 70, 2.75" Altazimuth refractor
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The Celestron PowerSeeker 70 altazimuth refractor is an economicalintroduction to casual astronomy and nature study for the backyardastronomer, but one that can supply good images of nature, the Moon, theplanets, and many of the brighter deep space objects . . .





. . . our 34th year