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30

ASTRONOMY FORMULAS FOR YOUR 

ZHUMELL DOBSONIAN TELESCOPE

MAGNIFICATION

To determine the magnification of a telescope and eyepiece 
combinantion, divide the telescope focal length be the eye-
piece focal length.

Magnification (x) = Telescope Focal Length (mm)/Eyepiece 
Focal Length (mm)

 

Ex: 32mm Eyepiece with a 304x1500mm telescope. 

 

Magnification = 1500mm/32mm

 

Magnification = 46.875x

FOCAL RATIO

To determine the focal ratio of a telescope, divide the focal 
length of the telescope by the aperture.

Focal Ratio (f/x)= Telescope Focal Length (mm)/Aperture (mm)

 

Ex: Focal Ratio of a 304x1500mm telescope.

 

Focal Ratio (f/x)= 1500mm/304mm

 

Focal Ratio (f/x)=f/4.93

Summary of Contents for Z12

Page 1: ...0 1 5 W 30 W 45 W 60 W 1 5 E 75 W OWNER S MANUAL DOBSONIAN TELESCOPE ZHUMELL Z12 DELUXE DOBSONIAN REFLECTOR TELESCOPE...

Page 2: ...ell you get field tested precision crafted optics at the best possible value So even if you re just starting out as an amateur birder or astronomer you don t have to settle for entry level products Zh...

Page 3: ...Astronomy Terminology 11 Telescope Terminology 12 FAQs 13 Warranty i Base Assembly ii Optical Tube Assembly i 1 25 inch Eyepieces ii 2 inch Eyepieces iii Altitude and Azimuth iv Focusing the Image v C...

Page 4: ...escope is built with the highest quality optics and top notch construction to provide years of reliable functionality but will require proper care If after reading this manual you still have questions...

Page 5: ...Never use an eyepiece filter as a solar filter Only solar filters will completely cover the opening of the optical tube and provide proper eye protection Make sure no screws are loose before using te...

Page 6: ...laser is reflected onto the reticle If you cannot see the laser reflected back onto the reticle align the secondary mirror by adjusting the secondary mirror collimation screws until the laser is refl...

Page 7: ...l 1 Brush telescope optics with camelhair brush or blow off dust with an ear syringe can be purchased at any pharmacy Do not use a commercial photographic lens cleaner 2 Remove organic materials e g f...

Page 8: ...wtonian collimator 32 mm eyepiece 2 inch format 9 mm eyepiece 1 25 inch format Moon filter 1 25 inch format Box 2 of 2 8x50 finderscope Handle 10 long black Allen screws 2 medium silver Allen screws 3...

Page 9: ...Bearing Plates 3 e Handle and 2 silver Allen screws f Eyepiece Tray and 2 black Philips screws g Feet 3 h Long Black Allen Screws 10 i Allen Wrench j Adjustment Bolt with 2 washers 1 ball bearing and...

Page 10: ...o complete the box Be sure that all three sides are firmly attached and feel stable STEP 2 Connect the Base Front to the Left Base Side using the pre drilled holes in the Base Front and 2 Long Black A...

Page 11: ...and telescope to rotate in a lazy susan style STEP 5 First the feet must be attached to the Base Plate Choose the Base Plate with 1 center hole and 3 holes around the edge IMPORTANT The feet must be a...

Page 12: ...8 To assemble the Adjustment Bolt hold the parts in your hand in this order Small Washer Ball Bearing Large Washer Place them on the threaded bolt in that order with the small washer closest to the p...

Page 13: ...late and Base Housing assembly and place it on top of the Base Plate and Bearing Plate Assembly aligning the center hole with the Axle Sleeve The top assembly should now rotate freely over the bottom...

Page 14: ...r Side Bearings 2 d Laser Collimator e Battery Pack for Cooling Fan f 1 25 inch 9mm Plossl Eyepiece g 2 inch 30mm Plossl Eyepiece h 1 25 inch Moon Filter STEP 1 Remove the 2 bolts found on the opening...

Page 15: ...scope Bracket on the OTA Loosen the thumbscrew on the bracket with your fingers and slide the Finderscope into place Tighten the screw so that the Finderscope is secure You are now ready to insert an...

Page 16: ...humbscrew closest to the eyepiece hole It is part of the 1 25 inch adapter More on this adapter in the 2 inch eyepiece section 5 Take out your 1 25 inch eyepiece Remove the plastic covers and pull up...

Page 17: ...opening 3 Pull the adapter out of the focuser 4 Take out your 2 inch eyepiece Remove the plastic covers 5 Slide the chrome end of the eyepiece into the focuser 6 Tighten the bottom thumbscrew to hold...

Page 18: ...o let it move naturally never force your telescope to move BASICS FOR YOUR ZHUMELL DOBSONIAN TELESCOPE FOCUSING THE IMAGE 1 With an eyepiece in the focuser loosen both back thumbscrews on the left sid...

Page 19: ...MELL DOBSONIAN TELESCOPE TRANSPORTATION 1 IMPORTANT never try and transport both the base and OTA as a single unit Gently lift the OTA off the base and secure in a telescope case for transportation Mo...

Page 20: ...normal and is a result of the optical system design It can be corrected by using an erecting prism when viewing but it is not necessary to do so Using your finderscope will help you locate celestial m...

Page 21: ...he center of the finderscope crosshairs If not your finderscope must be re aligned 3 To align your finderscope slightly loosen the thumbscrews which on the finderscope bracket Gently move the findersc...

Page 22: ...rly keeping your telescope covered in the sun prevents the air inside from warming too drastically Your Zhumell Dobsonians comes with a cooling fan to help speed up the process of reaching thermal equ...

Page 23: ...tor star for this test is Megrez mag 3 4 the star in the Big Dipper connecting the handle to the dipper If Megrez is not visible elements in the air will negatively affect your view DARK ADAPTING YOUR...

Page 24: ...ject begins to leave your field of view gently nudge the OTA in the correct direction and bring it back to center Remember the higher the magnification at which you re viewing the smaller your field o...

Page 25: ...o yields great results Deep sky objects however typically look best at medium and low magnifications This is because they tend to be faint yet have apparent width Deep sky objects often fall from view...

Page 26: ...h as they do to the naked eye as tiny points of light against a dark sky Even powerful telescopes cannot magnify stars to appear as anything more than these pinpoints You can however enjoy the differe...

Page 27: ...worthwhile view of Saturn If you look closely enough you can see the Cassini division a thin dark gap in the rings You can also often make out one or more of Saturns moons including the largest Titan...

Page 28: ...sensitive enough to distinguish color from faint light STARHOPPING Starhopping is the most common and simplest way to reliably track down objects in the night sky It uses relative positioning beginni...

Page 29: ...face this general direction Find the brightest star in this constellation and center your telescope on it using your finderscope as a guide Consult your star chart again and determine the next bright...

Page 30: ...fication x Telescope Focal Length mm Eyepiece Focal Length mm Ex 32mm Eyepiece with a 304x1500mm telescope Magnification 1500mm 32mm Magnification 46 875x FOCAL RATIO To determine the focal ratio of a...

Page 31: ...ure in cm Ex Limiting Magnitude of a 304x1500mm telescope Limiting Magnitude 7 5 5LOG 30 4cm Limiting Magnitude 7 5 5 x 1 483 Limiting Magnitude 14 91 RESOLVING POWER To determine the resolving power...

Page 32: ...quinox is where right ascension is at 0h hours The autumnal equinox can be found at 12h R A ZENITH The zenith is the point in the celestial sphere directly above your head The zenith varies depending...

Page 33: ...called f stop provides a wider field of view Photographically the lower the f stop the shorter the exposure time needed to capture an object on film LIMITING MAGNITUDE The limiting magnitude of a tel...

Page 34: ...mated every time they are used THE IMAGE I SEE IN MY FINDERSCOPE IS NOT THE SAME AS THE IMAGE I SEE THROUGH MY TELESCOPE WHAT IS WRONG In order for the finderscope to show the same part of the sky whi...

Page 35: ...rimary mirror If you have questions about whether a particular mount will work the optical tube please check with the mount s manufacturer about the specifications for the mount WHY IS IT CALLED A DOB...

Page 36: ...anty To obtain warranty service the damaged equipment must be returned to Zhumell Our Customer Care associates will be happy to assist you in completing this return to get your Zhumell in working orde...

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