CELESTRON 21023 FirstScope 76 Tabletop Telescope User Guide
- June 9, 2024
- Celestron
Table of Contents
21023 FirstScope 76 Tabletop Telescope
User Guide
21023 FirstScope 76 Tabletop Telescope
FirstScope 76 Tabletop Telescope User Guide
Verify that all parts are present. Your Cometron FirstScope 76 telescope
includes the preassembled base, optical tube, finderscope assembly, and two
eyepieces.
To install the fi nderscope, remove the nuts on side of tube, place
the finderscope bracket over threaded posts and replace the nuts.
Loosen the thumbscrews on the focuser and remove the focuser
cap.
Insert the chrome barrel of the eyepiece into the focuser and
secure with setscrews.
Remove main telescope lens cap and caps on the fi nderscope.
Loosen the altitude lock nut by turning it clockwise and hold the
bottom of the tube with your other hand. 
Look through the fi nderscope and roughly point your telescope at
your target.
NOTE: Align the fi nderscope fi rst before proceeding. See the next page for
directions. 
Center your target in the fi nderscope’s fi eld of view. Then make
sure it is in the telescope eyepiece’s fi eld of view and tighten the altitude
lock nut.
Focus your telescope by turning the two knobs under the eyepiece
until you have a sharp image.
Celestron’s free SkyPortal app for iOS and Android can help you
locate and identify a wide array of celestial objects quickly and easily.
ALIGNING THE FINDERSCOPE
The finder is one of the most important parts of your telescope. It helps you locate objects and center them in the eyepiece. The first time you assemble your telescope, you need to align the finder to the telescope’s main optics. It’s best to do this during the day.*
- SOLAR WARNING! Never attempt to view the Sun through any telescope without a proper solar filter!
CHOOSE A TARGET
Take the telescope outside during the day and find an easily recognizable object, like a streetlight, license plate or sign. The object should be as far away as possible, but at east a quarter mile away.
CENTER THE TARGET IN THE EYEPIECE
Look through the telescope using your lower powered eyepiece. Move the telescope until the object you chose lies in the center of the view. If the image is blurry, gently turn the focus knobs until it comes into sharp focus.
LOOK THROUGH FINDERSCOPE
Once the object is centered in your 20mm eyepiece, look through the finderscope and locate the crosshair reticle.
ADJUST THE FINDERSCOPE
Without moving the telescope, use the three finger knobs on the finderscope bracket to move the finder around in the bracket until the crosshair appears over the same object you are observing in the telescope’s 20mm eyepiece.
TIP: Try adjusting one screw at a time. Loosen one screw by half a turn and tighten another by the same amount to ensure the finderscope remains securely held in place.
YOUR FINDERSCOPE IS NOW ALIGNED!
It should not require realignment unless it is bumped or dropped.
YOUR FIRST NIGHT OUT THE MOON
The best and easiest target for you to try to view first is the Moon. Try observing the Moon at different points in its phase cycle. The best time to view the Moon is from two days after a New Moon up to a few days before a Full Moon. During this period, you will be able to see the most detail in the craters and lunar mountain ranges.
With the Moon visible in the sky, set up your telescope with the 20mm eyepiece
installed. Move the telescope so that it is roughly pointing toward the
Moon.
Look through the finderscope and locate the crosshair reticle.
Continue moving the telescope until the crosshair appears over the
Moon.
Look through the telescope’s 20mm eyepiece. Gently turn the focus
knobs to adjust the sharpness of the image.
CONGRATULATIONS! YOU HAVE NOW OBSERVED YOUR FIRST CELESTIAL OBJECT!
To get a closer view of the Moon, loosen the setscrews on the
focuser and remove the 20mm eyepiece. Replace it with your 10mm eyepiece and
tighten the setscrews to secure it in place. The 10mm eyepiece will give you
significantly more magnification, making the Moon appear much larger.
NOTE: You may need to adjust the focus knobs when you change eyepieces to
make sure you are getting the sharpest image possible.
You can view many other celestial objects, such as planets, star
clusters and nebulae using this same technique and your SkyPortal app to
determine celestial objects’ positions.
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SOLAR WARNING:
Never attempt to view the sun through any
telescope without a proper solar fi lter.
NEED ASSISTANCE?
Contact Celestron Technical Support
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