Celestron 31056 Short Exposure Prime F o c u s, Lunar Phase ISO Crescent Quarter 125 Full 250

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Short Exposure Prime F o c u s

Short exposure prime focus photography is the best way to begin recording celestial objects. It is done with the camera attached to the telescope without an eyepiece or camera lens in place. To attach your camera, you need the T-adapter and a T-Ring for your specific camera (i.e., Minolta, Nikon, Pentax, etc.). The C150-HD and G-8N focuser have built-in T-adapter and are ready to accept a 35mm camera body. The T- Ring replaces the 35mm SLR camera’s normal lens. Prime focus photography allows you to capture the entire solar disk (if using the proper filter) as well as the entire lunar disk. To attach your camera to your telescope:

1Remove the eyepiece from the 1 1/4" eyepiece holder.

2Unthread the 1 1/4" eyepiece holder from the focuser assembly. This will expose the male thread of the built-in T-adapter.

3Thread the T-ring onto the exposed T-adapter threads.

4Mount your camera body onto the T-Ring the same as you would any other lens.

With your camera attached to the telescope, you are ready for prime focus photography. Start with an easy object like the Moon. Here’s how to do it:

1. Load your camera with film that has a moderate-to-fast speed (i.e., ISO rating). Faster films are more desirable when the Moon is a crescent. When the Moon is near full, and at its brightest, slower films are more desirable. Here are some film recommendations:

T-Max 100

T-Max 400

Any 100 to 400 ISO color slide film

Fuji Super HG 400

2. Center the Moon in the field of your telescope.

3. Focus the telescope by turning the focus knob until the image is sharp.

4. Set the shutter speed to the appropriate setting (see table 6-1).

5. Trip the shutter using a cable release.

6.Advance the film and repeat the process.

 

 

 

 

 

Lunar Phase

ISO 50

ISO 100

ISO 200

ISO 400

 

 

 

 

 

Crescent

1 / 2

1 / 4

1 / 8

1/15

Quarter

1/15

1/30

1/60

1/125

 

 

 

 

 

Full

1/30

1/60

1/125

1/250

 

 

 

 

 

 

 

Table 6-1

 

 

Above is a listing of recommended exposure times when photographing the Moon at the prime focus of your Celestron Newtonian.

48 • Celestial Photography

Image 48
Contents C150-HD and G-8N Newtonian Page B L E N T E N T S Celestial Photography T R O D U C T I O N How to Use this Manual Word of Caution Newtonian Optical System S E M B L I N G Y O U R N E W T O N I a N T E L E S C O P E Unpacking Your G-8NG-8N C150-HD Setting Up the Tripod Adjusting the Tripod HeightAttaching the Accessory Tray Attaching the Equatorial Mount They are needed later for polar alignmentAttaching the R.A. Slow Motion Knob Attaching the Declination Slow Motion Knob Attaching the Counterweight Bar and Counterweight Attaching the Telescope to the Mount For G-8N Attaching the Telescope to the Mount For C150- HD Removing the Lens Cap Balancing the Telescope in R.ABalancing the Telescope in DEC CompletelyG-8N C150-HD Installing the Finderscope Installing the Eye- piece Technical Specifications Image Orientation ActualVeiw NewtonianViewFocusing Aligning the Finder Your First Look Daytime ObservingNighttime Observing Calculating Magnification Determining Field of View T R O N O M Y B a S I C S Celestial Coordi- nate SystemMotion of the Stars Polar Alignment DefinitionFinding the Pole Latitude Scales Pointing at Polaris Declination Drift Aligning the R.A Setting Circle Polar Alignment FindersL E S T I a L O B S E R V I N G Observing the Moon PlanetsObserving the S u n Observing Deep-Sky ObjectsUsing the Setting Circles Star Hopping Celestial Observing Viewing Conditions TransparencySky Illumination SeeingCelestial Observing L E S T I a L P H O T O G R a P H Y Lunar Phase ISO Crescent Quarter 125 Full 250 Short Exposure Prime F o c u sPiggyback Celestial Photography Care and Cleaning of the Optics Collimation L E S C O P E M a I N T E N a N C EOr back out the holder screws more than one 1 to two 2 turns T I O N a L a C C E S S O R I E S Optional Accessories Single Axis Motor Drive System #93518 Themessiercatalog Great Orion Nebula Elliptical Galaxy List of Bright Stars For Further Reading Celestron ONE Year Warranty