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Viewing conditions affect what you can see through your telescope during an observing session.  Conditions include 
transparency, sky illumination, and seeing.  Understanding viewing conditions and the effect they have on observing 
will help you get the most out of your telescope. 

 

Transparency 
 

Transparency  is  the  clarity  of  the  atmosphere  which  is  affected  by  clouds,  moisture,  and  other  airborne  particles.  
Thick  cumulus  clouds  are  completely  opaque  while  cirrus  can  be  thin,  allowing  the  light  from  the  brightest  stars 
through.  Hazy skies absorb more light than clear skies making fainter objects harder to see and reducing contrast on 
brighter objects.  Aerosols ejected into the upper atmosphere from volcanic eruptions also affect transparency.  Ideal 
conditions are when the night sky is inky black. 
 
 

Sky Illumination 

 

General  sky  brightening  caused  by  the  Moon,  aurorae,  natural  airglow,  and  light  pollution  greatly  affect 
transparency.  While not  a problem  for  th e brighter  stars  and  planets,  bright  skies reduce the contrast  of  extended 
nebulae  making  them  difficult,  if  not  impossible  to  see.   To  maximize  your  observing,  limit  deep  sky  viewing  to 
moonless  nights  far  from  the  light  polluted  skies  found  around  major  urban  areas.   LPR  filters  enhance  deep  sky 
viewing from light polluted areas by blocking unwanted light while transmitting light from certain deep sky objects.  
You can, on the other hand, observe planets and stars from light polluted areas or when the Moon is out. 
 

Seeing 

 
Seeing  conditions  refers  to  the  stability  of  the  atmosphere  and  directly  affects  the  amount  of  fine  detail  seen  in 
extended  objects.   The  air  in  our  at mosphere  acts  as  a  lens  which  bends  and  distorts  incoming  light  rays.   The 
amount of bending depends on air density.  Varying temperature layers have di fferent densities and, therefore, bend 
light differently.  Light rays from the sa me object arrive slightly displaced creating an imperfect or smeared image.  
These atmospheric disturbances vary from time-to-time and place-to-place.  The size of the air parcels compared to 
your aperture determines the "seeing" quality.  Under good seeing conditions, fine detail is visible on the brighter 
planets like Jupiter and Mars, and stars are pinpoint images.  Under poor seeing conditions, images are blurred and 
stars appear as blobs.   
 
The conditions described here apply to both visual and photographic observations. 
 
 
 
 

 
 

 

Figure 5-3 

Seeing conditions directly affect image quality.  These drawings represent a point source 
(i.e., star) under bad seeing conditions (left) to excellent conditions (right).  Most often, 
seeing conditions produce images that lie somewhere between these two extremes. 

 
 
 
 
 
 
 

 

19

Содержание SPACE LAUNCHER 50 09102

Страница 1: ...SPACE LAUNCHER Series SPACE LAUNCHER Series T Te el le es sc co op pe es s I IN NS ST TR RU UC CT TI IO ON N M MA AN NU UA AL L SPACE LAUNCHER 50 09102 SPACE LAUNCHER 60 09103 SPACE LAUNCHER 76 09104 ...

Страница 2: ...E BASICS 11 Image Orientation 12 Focusing 12 Calculating Magnification 12 Determining Field of View 13 General Observing Hints 13 ASTRONOMYBASICS 14 The Celestial Coordinate System 14 Motion of the Stars 15 CELESTIAL OBSERVING 16 Observing the Moon 16 Observing the Planets 16 Observing the Sun 16 Observing Deep Sky Objects 17 Seeing Conditions 19 ASTROPHOTOGRAPHY 20 Short Exposure Prime Focus Phot...

Страница 3: ...platform Quick and easy no tool set up We have to give one All models can be used terrestrially as well as astronomically with the standard accessories included Take time to read through this manual before embarking on your journey through the Universe It may take a few observing sessions to become familiar with your telescope so you should keep this manual handy until you have fully mastered your...

Страница 4: ...ACE LAUNCHER SPACE LAUNCHER 1 Objective Lens 7 Altitude Slow Motion Rod Assembly not on 50AZ 2 Telescope Optical Tube 8 Accessory Tray 3 Finderscope 9 Tripod 4 Eyepiece 10 Azimuth Lock not on 50AZ 5 Diagonal 11 Alt Az Mount 6 Focus Knob 12 Altitude Locking Knob 4 ...

Страница 5: ...nian 1 Finderscope 7 Azimuth Lock 2 Eyepiece 8 Accessory Tray 3 Collimation Adjustment Screws in rear 9 Tripod 4 Telescope Optical Tube 10 Alt Az Mount 5 Primary Mirror 11 Altitude Lock 6 Altitude Slow Motion Rod Assembly 12 Focus Knob 5 ...

Страница 6: ...lightly on the tripod leg brace Figure 2 2 The very top of the tripod is called the tripod head AZ mount 3 Next we will install the tripod accessory tray Figure 2 3 onto the tripod leg brace center of Figure 2 2 4 On the bottom of the tripod tray is a screw attached to the center except the 50AZ The screw attaches into a threaded hole in the center of the tripod leg brace by turning it clockwise n...

Страница 7: ...the mechanism with the provided tool shown on the far left of Figure 2 7 and put the rod in place as shown in Figure 2 7 Then put the screw through the hole in the rod and into the mechanism and tighten it 3 Thread the altitude locking knob out so the hole is clear in the eyebolt see Figure 2 8 4 Put the rod of the assembly through the eyebolt and then tighten the altitude locking knob Figure 2 9 ...

Страница 8: ...onal is an erect image model that corrects the image to be right side up and oriented correctly left to right which is much easier to use for terrestrial observing Also the diagonal can be rotated to any position which is most favorable for you To install the diagonal and eyepiece 1 Insert the small barrel of the diagonal into the 1 25 eyepiece adapter of the focus tube on the refractor Figure 2 1...

Страница 9: ...ow w L Le en ns s Your telescope also comes with a 3x Barlow Lens which triples the magnifying power of each eyepiece However the greatly magnified images should only be used under ideal conditions see the Calculating Magnification section of this manual Figure 2 16 To use the Barlow lens with refractors remove the diagonal and insert the Barlow directly into the focuser tube You then insert an ey...

Страница 10: ...g toward the front of the optical tube 5 Remove the lens caps from both ends of the finderscope A Al li ig gn ni in ng g t th he e F Fi in nd de er rs sc co op pe e Use the following steps to align the finderscope 1 Locate a distant daytime object and center it in a low power eyepiece in 20mm the main telescope 2 Look through the finderscope the eyepiece end of the finderscope and take notice of t...

Страница 11: ...he mirror at the back end There light is bent forward in the tube to a single point its focal point Since putting your head in front of the telescope to look at the image with an eyepiece would keep the reflector from working a flat mirror called a diagonal intercepts the light and points it out the side of the tube at right angles to the tube The eyepiece is placed there for easy viewing Newtonia...

Страница 12: ...ttached to the telescope However when using a camera you should always wear corrective lenses to ensure the sharpest possible focus If you have astigmatism corrective lenses must be worn at all times C Ca al lc cu ul la at ti in ng g M Ma ag gn ni if fi ic ca at ti io on n You can change the power of your telescope just by changing the eyepiece ocular To determine the magnification of your telesco...

Страница 13: ...pparent field of view of 50 Divide the 50 by the magnification which is 35 power This yields an To convert degrees to feet at 1 000 yards which is more useful for terrestrial observing simply multiply by 52 5 Continuing with our example multiply the angular field of 1 4 by 52 5 This produces a linear field width of 74 feet at a distance of one thousand yards G Ge en ne er ra al l O Ob bs se er rv ...

Страница 14: ... or DEC for short Lines of declination are named for their angular distance above and below the celestial equator The lines are broken down into degrees minutes of arc and seconds of arc Declination readings south of the equator carry a minus sign in front of the coordinate and those north of the celestial equator are either blank i e no designation or preceded by a plus sign The celestial equival...

Страница 15: ...er rise and never set You will never see the st ars complete one circle because the sunlight during the day washes out the starlight However part of this circular motion of stars in this region of the sky can be seen by setting up a camera on a tripod and opening the shutter for a couple hours The timed exposure will reveal semicircles that revolve around the pole This description of stellar motio...

Страница 16: ... to see the cloud belts of Jupiter and the great Red Spot if it is visible at the time you are observing In addition you will also be able to see the moons of Jupiter as they orbit the giant planet Saturn with its beautiful rings is easily visible at moderate power Planetary Observing Hints Remember that atmospheric conditions are usually the limiting factor on how much planetary detail will be vi...

Страница 17: ... you to an object For successful star hopping it is helpful to know the field of view of you telescope If you re using the standard 20 mm eyepiece SPACE LAUNCHER with the telescope your field of view is approximately 1 4º or so If you know an object is 3º away from your present location then you just need to move about two fields of view If you re using another eyepiece then consult the section on...

Страница 18: ...cting the two stars 6 Look through the telescope and the Ring Nebula should be in your field of view The Ring Nebula s angular size is quite small and difficult to see 7 Because the Ring Nebula is rather faint you may need to use averted vision to see it Averted vision is a technique of looking slightly away from the object you re observing So if you are observing the Ring Nebula center it in your...

Страница 19: ...d around major urban areas LPR filters enhance deep sky viewing from light polluted areas by blocking unwanted light while transmitting light from certain deep sky objects You can on the other hand observe planets and stars from light polluted areas or when the Moon is out Seeing Seeing conditions refers to the stability of the atmosphere and directly affects the amount of fine detail seen in exte...

Страница 20: ...ry short exposures You will have to experiment with various settings and exposure times Much information can be obtained from your camera instruction manual which can supplement what you can find in detailed books on the subject matter Do your photography from a dark sky observing site if possible Remember this is just very simple photography For more detailed and serious astrophotography you need...

Страница 21: ...escope is in need of internal cleaning please call the factory for a return authorization number and price quote C Co ol ll li im ma at ti io on n o of f a a N Ne ew wt to on ni ia an n The optical performance of most Newtonian reflecting telescopes can be optimized by re collimating aligning the telescope s optics as needed To collimate the telescope simp ly means to bring its optical elements in...

Страница 22: ...be possible to correct this by re collimating only the primary mirror Procedure Please read this section completely before beginning To star collimate in the Northern Hemisphere point at a stationary star like the North Star Polaris It can be found in the north sky at a distance above the horizon equal to your latitude It s also the end star in the handle of the Little Dipper Polaris is not the br...

Страница 23: ...he star in your eyepiece by adjusting the collimation screws toward the three o clock position in the field of view It may only be necessary to adjust a screw enough to move the star s image from the center of the field of view to about halfway or less toward the field s edge when using a high power ocular Collimation adjustments are best made while viewing the star s position in the field of view...

Страница 24: ... 25 barrels Barlow Lens 01120 Used with any 60AZ 70AZ 76AZ eyepiece it doubles the magnification of that eyepiece A Barlow lens is a negative lens that increases the focal length of a telescope The 2x Omni is a 1 25 barrel is under 3 76mm long and weights only 4oz 113gr Moon Filter 01142 This is an economical 1 25 eyepiece filter for 60AZ 70AZ 76AZ for reducing the brightness of the moon and impro...

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