Celestron EdgeHD 800, EdgeHD 1100, EdgeHD 1400, EdgeHD 9.25, EdgeHD 8 Instruction Manual
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INSTRUCTION MANUAL
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Your telescope is designed to give you years of fun and rewarding observations. However, there are a few things to consider before using
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your telescope that will ensure your safety and protect your equipment.
Warning
Never look directly at the sun with the naked eye or with a telescope (unless you have the proper solar
filter). Permanent and irreversible eye damage may result.
Never use your telescope to project an image of the sun onto any surface. Internal heat build-up can damage the telescope and any
accessories attached to it.
Never use an eyepiece solar filter or a Herschel wedge. Internal heat build-up inside the telescope can cause these devices to crack or
break, allowing unfiltered sunlight to pass through to the eye.
Never leave the telescope unsupervised, either when children are present or adults who may not be familiar with the correct operating
procedures of your telescope
Diameter
Focal Length
Eyepiece
Finderscope
Diagonal
Technical Specs
Highest Useful Magnification
Lowest Useful Magnification
Limiting Stellar Magnitude
Resolution: Rayleigh
Dawes Limit
Light Gathering Power
Field of View: standard eyepiece
Linear FOV (@1000 yds)
Optical Coatings - Standard
Secondary Mirror Obstruction
by Area
by Diameter
Optical tube length
.
EdgeHD 800 EdgeHD 925 EdgeHD 1100 EdgeHD 1400
203mm (8") EdgeHD
Optics
2032mm F/10 2350mm F/10 2800mm F/10 3910mm F/10
40mm - 1.25" (51x) 23mm - 2" (102x) 23mm - 2" (122x) 23mm - 2" (170x)
9x50 9x50 9x50 9x50
90° - 1.25"
480x 555x 660x 840x
29x 34x 40x 51x
14 14.4 14.7 15.3
.68 arc seconds .59 arc seconds .50 arc seconds .39 arc seconds
.57 arc seconds .49 arc seconds .42 arc seconds .33 arc seconds
843x unaided eye 1127x unaided eye 1593x unaided eye 2579x unaided eye
.85º .8º .67º .48º
44 ft. 42 ft. 35 ft. 25 ft.
Starbright XLT Coating Starbright XLT Coating Starbright XLT Coating Starbright XLT Coating
2.7" 3.35" 3.75" 4.5"
11% 13% 12% 10%
34% 36% 34% 32%
17 inches 22 inches 24 inches 31 inches
235mm (9.25") EdgeHD
Optics
90° - 2" with 1.25"
adapter
280mm (11") EdgeHD
Optics
90° - 2" with 1.25"
adapter
356mm (14") EdgeHD
Optics
90° - 2" with 1.25"
adapter
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A
1.25" Star
Diagonal
Visual Back
1.25"
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The visual back is the accessory that allows you to attach all visual accessories to the 8" telescope. The 8" telescope optical
tubes come with the visual back installed. If it is not already on the tube it can be attached as follows:
1. Remove the rubber cover on the rear cell.
2. Place the knurled slip ring on the visual back over the threads on the rear cell (Fig 1-1).
3. Hold the visual back with the set screw in a convenient position and rotate the knurled slip ring clockwise until tight.
Once this is done, you are ready to attach other accessories, such as eyepieces, diagonal prisms, etc.
If you want to remove the visual back, rotate the slip ring counterclockwise until it is free of the rear cell.
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The star diagonal is a prism or mirror that diverts the light at a right angle to the light path of the telescope. This allows you
to observe in positions that are physically more comfortable than if you looked straight through.
To attach the 1.25" star diagonal onto the 8" optical tube:
1. Turn the set screw on the visual back until its tip no
longer extends into (i.e., obstructs) the inner diameter of
the visual back.
Eyepiece
2. Slide the chrome portion of the star diagonal into the
visual back.
3. Tighten the set screw on the visual back to hold the star
diagonal in place.
If you wish to change the orientation of the star diagonal, loosen
the set screw on the visual back until the star diagonal rotates
freely. Rotate the diagonal to the desired position and tighten the
Figure 1-1 – Visual accessories for the 8"
set screw.
To attach the 2" star diagonal onto the 9.25/11/14" optical tubes:
1. Remove the visual back from the rear of the tube.
2. Attach the threaded ring of the 2" diagonal to the rear cell of
the telescope.
3. Loosen the thumb screws on the side of the diagonal and
remove the 1.25" adapter from the barrel of the diagonal.
If you wish to change the orientation of the 2" star diagonal, loosen the
retaining ring that attaches the diagonal to the rear cell. Rotate the
diagonal to the desired position and tighten the retaining ring.
2 inch
Eyepiece
2" Mirror
Diagonal
Figure 1-2 – Visual accessories for the 9.25/11/14"
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Figure
1-3
Pivot
The eyepiece, or ocular, is an optical element that magnifies the image focused by the telescope. The eyepiece fits into either
the visual back directly (8" only) or the star diagonal. To install an eyepiece:
1. Loosen the set screw on the star diagonal until the tip no longer extends into the inner diameter of the eyepiece end
of the diagonal.
2. Slide the chrome portion of the eyepiece into the star diagonal.
3. Tighten the set screw on the star diagonal to hold the eyepiece in place.
To remove the eyepiece, loosen the set screw on the star diagonal and slide the eyepiece out.
Eyepieces are commonly referred to by focal length and barrel diameter. The focal length of each eyepiece is printed on the
eyepiece barrel. The longer the focal length (i.e., the larger the number) the lower the eyepiece power and the shorter the
focal length (i.e., the smaller the number) the higher the magnification. Generally, you will use low-to-moderate power when
viewing. For more information on how to determine power, see the section on “Calculating Magnification.”
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The EdgeHD telescopes comes with a 9x50 finderscope. The specifications for a finderscope stand for the magnification and
the aperture, in millimeters, of the scope. So, a 9x50 finder magnifies objects nine times and has a 50mm objective lens.
Finderscope Installation
The finderscope must first be mounted in the included quick-release bracket then attached to the rear cell of the
telescope.
To install the finderscope:
1. Locate the finderscope mounting bracket attached to the bottom portion of the finder bracket. Loosen the two thumb
screws to slide the mounting bracket from the finderscope bracket.
2. Find the two holes in the rear cell of the telescope on the top left, when looking from the back of the tube.
3. Place the mounting bracket over the two holes of the rear cell as shown in the figure 1-5.
4. Insert the screws through the bracket and into the rear cell.
WARNING: If you remove the mounting bracket, do not
completely thread the screws back into the rear cell of the
telescope. The screws may be long enough to obstruct the
movement of, and possibly damage the primary mirror.
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Alignment Screws
With the bracket firmly attached to the telescope, you are ready to
attach the finder to the bracket.
1. Slide the O-Ring over the back of the finderscope and
position it on the tube toward the objective end of the
finderscope.
Screw
Figure 1-4
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Quick release
Screws
Finderscope
Mounting
Bracket
2. Slide the eyepiece end of the finderscope into the front ring of the bracket (the front ring is the one without the
adjustment screws), then through the back ring. It may be necessary to push down the spring loaded pivot screw so
that the finder will pass through the back ring (see figure 1-3)
3. Push the finder back until the O-Ring is snug inside the front ring of the finder bracket.
4. Hand tighten the two alignment thumb screws until they make contact with the finderscope.
The finderscope bracket comes in two pieces; the mounting bracket (left) and the finder bracket (right)
Aligning the Finderscope
The finderscope is adjusted using two adjustment screws, located on the top and on the right (when looking though the finder)
of the finder bracket and a spring loaded pivot screw (located on the left side of the bracket). This allows you to turn the top
adjustment screw to move the finderscope up and down, and turn the right adjustment screw to move the finderscope right to
left. The spring loaded pivot screw puts constant pressure on the finder so that the adjustment screws are always making
contact with the finder.
To make the alignment process a little easier, you should perform this task in the daytime when it is easier to locate objects in
the telescope without the finder. To align the finder:
1. Choose a conspicuous object that is in excess of one mile away. This will eliminate any possible parallax effect
between the telescope and the finder.
2. Point your telescope at the object you selected and center it in the main optics of the telescope.
3. Lock the azimuth and altitude clamps to hold the telescope in place.
4. Check the finder to see where the object is located in the field of view.
5. Adjust the thumb screws on the finder bracket, until the cross hairs are centered on the target.
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Figure 1-5
The 8, 9.25 and11" lens cap utilizes a bayonet-type locking mechanism to hold it in place. To remove the lens cap, hold the
cover firmly and rotate the outer edge 1/2” counterclockwise and pull off.
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A telescope is an instrument that collects and focuses light. The nature of the optical design determines how the light is
Figure 2
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focused. Some telescopes, known as refractors, use lenses. Other telescopes, known as reflectors, use mirrors. The EdgeHD
optical system (Apanatic Schmidt) uses a combination of mirrors and lenses and is referred to as a compound or catadioptric
telescope. This unique design offers large-diameter optics while maintaining very short tube lengths, making them extremely
portable. The EdgeHD system consists of a zero power corrector plate, a spherical primary mirror, and a secondary mirror
along with a set of field flattening lens integrated into the baffle tube . Once light rays enter the optical system, they travel the
length of the optical tube three times.
The optics of an EdgeHD telescopes have Starbright XLT coatings - enhanced multi-layer coatings on the primary and
secondary mirrors for increased reflectivity and a fully coated corrector for the finest anti-reflection characteristics.
Inside the optical tube, a black tube extends out from the center hole in the primary mirror. This is the primary baffle tube
and it prevents stray light from passing through to the eyepiece or camera.
Figure 2-1
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Image Orientation
The image orientation changes depending on how the eyepiece is inserted into the telescope. When using the star diagonal,
the image is right-side-up, but reversed from left-to-right (i.e., mirror image). If inserting the eyepiece directly into the visual
back (i.e., without the star diagonal), the image is upside-down and reversed from left-to-right (i.e., inverted). This is normal
for the EdgeHD design.
Actual image orientation as seen
with the unaided eye
Reversed from left to right, as
viewed with a Star Diagonal
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Inverted image, as viewed with
the eyepiece directly in telescope
Focusing
Your telescope's focusing mechanism controls the primary mirror which is mounted on a ring
that slides back and forth on the primary baffle tube. The focusing knob, which moves the
primary mirror, is on the rear cell of the telescope just below the star diagonal and eyepiece.
Turn the focusing knob until the image is sharp. If the knob will not turn, it has reached the
end of its travel on the focusing mechanism. Turn the knob in the opposite direction until the
image is sharp. Once an image is in focus, turn the knob clockwise to focus on a closer object
and counterclockwise for a more distant object. A single turn of the focusing knob moves the
primary mirror only slightly. Therefore, it will take many turns (about 30) to go from close
focus to infinity.
For astronomical viewing, out of focus star images are very diffuse, making them difficult to
see. If you turn the focus knob too quickly, you can go right through focus without seeing the
image. To avoid this problem, your first astronomical target should be a bright object (like
the Moon or a planet) so that the image is visible even when out of focus. Critical focusing is
best accomplished when the focusing knob is turned in such a manner that the mirror moves
against the pull of gravity. In doing so, any mirror shift is minimized. For astronomical
observing, both visually and photographically, this is done by turning the focus knob
counterclockwise.
Mirror Support Clutches
The EdgeHD Optical tube is equipped with mirror tension
clutches to help support and minimize lateral movement of
the primary mirror during astrophotography.
Figure 2-3 -The emblem on
the end of the focus knob
shows the correct rotational
direction for focusing your
telescope
.
To use the mirror clutches:
1. Use the focus knob to adjust the primary mirror
Mirror
Lock
Knobs
to the desired focus.
2. Once in focus, turn the two mirror lock knobs
clockwise until both are very tight and can be
turned no further.
Warning! Once the mirror is locked down, do not turn
the focuser knob without loosening the mirror locks first.
Figure 2-4 – Mirror Support Clutches
Although turning the focus knob should not damage the
telescope, undue stress can be placed on the focus mechanisms causing excessive image shift while focusing.
Calculating Magnification
You can change the power of your telescope just by changing the eyepiece (ocular). To determine the magnification of your
telescope, simply divide the focal length of the telescope by the focal length of the eyepiece used. In equation format, the
formula looks like this:
Focal Length of Telescope (mm)
Magnification =
Let’s say, for example, you are using the 40mm Plossl eyepiece. To determine the magnification you simply divide the focal
length of your telescope (the C8 for example has a focal length of 2032mm) by the focal length of the eyepiece, 40mm.
Dividing 2032 by 40 yields a magnification of 51 power.
Focal Length of Eyepiece (mm)
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