Specifications
Optical Design
Rowe-Ackermann Schmidt
Aperture
279 mm
Focal Length
620 mm
Focal Ratio
2.22
Central obstruction diameter
114 mm
Optical Coatings
StarBright XLT
Total Telescope Kit Weight
35 lbs
Optical Window
Broadband AR fully-multicoated removable optical window
Focuser
FeatherTouch MicroFocuser, 10:1 fine focus ratio
Cooling Fan
12V DC, tip positive polarity
Optical Tube Length
33 in
Backfocus from included camera adapters
55 mm
Total back focus from flat surface above optical window
72.8 mm
On-axis RMS spot size
<2.00 µm
RMS spot size 21 mm off-axis
<2.25 µm
Relative illumination 21 mm off-axis
83%
Image Circle Diameter
70 mm
Rowe-Ackermann Schmidt Astrograph
Telescope
INSTRUCTION MANUAL
Model: 91075
CELESTRON TWO YEAR LIMITED WARRANTY
A
. Celestron warrants your telescope mount to be free from defects in materials and workmanship for two years.
Celestron will repair or replace such product or part thereof which, upon inspection by Celestron, is found to be
defective in materials or workmanship. As a condition to the obligation of Celestron to repair or replace such product,
the product must be returned to Celestron together with proof-of-purchase satisfactory to Celestron.
B
. The Proper Return Authorization Number must be obtained from Celestron in advance of return. Call Celestron at
(310) 328-9560 to receive the number to be displayed on the outside of your shipping container.
All returns must be accompanied by a written statement setting forth the name, address, and daytime telephone
number of the owner, together with a brief description of any claimed defects. Parts or product for which replacement
is made shall become the property of Celestron.
The customer shall be responsible for all costs of transportation and insurance, both to and from the factory of
Celestron, and shall be required to prepay such costs.
Celestron shall use reasonable efforts to repair or replace any telescope mount covered by this warranty within thirty
days of receipt. In the event repair or replacement shall require more than thirty days, Celestron shall notify the
customer accordingly. Celestron reserves the right to replace any product which has been discontinued from its
product line with a new product of comparable value and function.
This warranty shall be void and of no force of effect in the event a covered product has been modified in de-
sign or function, or subjected to abuse, misuse, mishandling or unauthorized repair. Further, product malfunction or
deterioration due to normal wear is not covered by this warranty.
CELESTRON DISCLAIMS ANY WARRANTIES, EXPRESS OR IMPLIED, WHETHER OF MERCHANTABILITY OF
FITNESS FOR A PARTICULAR USE, EXCEPT AS EXPRESSLY SET FORTH HEREIN. THE SOLE OBLIGATION OF
CELESTRON UNDER THIS LIMITED WARRANTY SHALL BE TO REPAIR OR REPLACE THE COVERED PRODUCT, IN
ACCORDANCE WITH THE TERMS SET FORTH HEREIN. CELESTRON EXPRESSLY DISCLAIMS ANY LOST PROFITS,
GENERAL, SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES WHICH MAY RESULT FROM BREACH OF ANY
WARRANTY, OR ARISING OUT OF THE USE OR INABILITY TO USE ANY CELESTRON PRODUCT. ANY WARRANTIES
WHICH ARE IMPLIED AND WHICH CANNOT BE DISCLAIMED SHALL BE LIMITED IN DURATION TO A TERM OF TWO
YEARS FROM THE DATE OF ORIGINAL RETAIL PURCHASE.
Some states do not allow the exclusion or limitation of incidental or consequential damages or limitation on how long
an implied warranty lasts, so the above limitations and exclusions may not apply to you.
This warranty gives you specific legal rights, and you may also have other rights which vary from state to state.
Celestron reserves the right to modify or discontinue, without prior notice to you, any model or style telescope.
If warranty problems arise, or if you need assistance in using your telescope mount contact:
CELESTRON, LLC.
Customer Service Department
2835 Columbia Street • Torrance, CA 90503 • Tel. 800.421.9649
Monday-Friday 8AM-4PM PST • ©2014 Celestron • All rights reserved.
NOTE:
This warranty is valid to U.S.A. and Canadian customers who have purchased this product from an authorized
Celestron dealer in the U.S.A. or Canada. Warranty outside the U.S.A. and Canada is valid only to customers who
purchased from a Celestron’s International Distributor or Authorized Celestron Dealer in the specific country. Please
contact them for any warranty service.
Dew Prevention
The Schmidt corrector is especially susceptible to condensation forming because the glass is
immediately exposed to the outside air, just like the windshield on your car. If the temperature
outside drops below the dew point, dew may form on the corrector within minutes.
The easiest way to prevent dew is to add an optional dew shield, available from Celestron,
which shrouds the corrector and keeps the air immediately surrounding the corrector slightly
warmer than the ambient temperature. If conditions are more severe, a dew heater, commonly
available from other manufacturers, can be added to apply slight heat to the corrector lens to
keep it dry all night.
If dew has already formed on the corrector, point the telescope downward and allow the
telescope to dry. You can also use a hairdryer to heat the corrector and evaporate the moisture
to dry the telescope.
Dew does not harm the telescope, but can lead to faster dust build up. Do not store the
telescope if covered in dew. Allow the telescope to dry first.
Care and Cleaning of the Optics
Dust should normally be removed with a pressured air can, or a camel hair brush. Spray at an
angle to the lens for approximately two to four seconds. Then, use an optical cleaning solution
and white tissue paper to remove any remaining debris. Apply the solution to the tissue and
then apply the tissue paper to the lens. Low pressure strokes should go from the center of the
corrector to the outer portion. Do NOT rub in circles!
You can use a commercially made lens cleaner or mix your own. A good cleaning solution is
isopropyl alcohol mixed with distilled water. The solution should be 60% isopropyl alcohol and
40% distilled water. Or, liquid dish soap diluted with water (a couple of drops per one quart of
water) can be used.
To minimize the need to clean your telescope, replace the dust cap once you have finished
using it.
Internal adjustments and cleaning should be done only by the Celestron repair department. If
your telescope is in need of internal cleaning, please call the factory for a return authorization
number and price quote.
