Celestron 4 Photography with the NexStar 4, Finding the North Celestial Pole

Photography with the NexStar 4

Afterlooking at the night sky for a while you may want to try photographingit. Inaddition to the specific accessories

requiredfor celestial photography, there is the need for a camera - but not just any camera. Thecamera does not have

to have many of the featuresoffered on today's state-of-the-art equipment. Forexample, you don't need auto focus

capabilityor mirrorlock up. Hereare the mandatory features a camera needs for celestial photography. First,a “B”

setting which allows for time exposures. This excludes point and shootcameras and limits the selection to SLR

cameras,the most common type of 35mm camera on the markettoday.

Second, the “B” or manual settingshould NOT run off the battery. Many new electronic cameras use the battery to

keep the shutter open duringtime exposures. Once the batteries are drained, usually aftera fewminutes, the shutter

closes, whether you were finished with the exposureor not. Look for a camera that has a manual shutter when

operating in the time exposuremode. Olympus, Nikon, Minolta, Pentax, Canon and others havemade such camera

bodies.

The camera must have interchangeable lenses so you can attach it to the telescope and so you can use a variety of

lenses forpiggyback photography. If you can't finda new camera, you can purchase a used camera body that is not

100-percentfunctional. Thelight meter, for example,does not have to be operational since you will be determining the

exposurelength manually.

You also need a cablerelease with a locking function to hold the shutter open while you do other things. Mechanical

andair releasemodels are avai lable.

The NexStar 4 has a special adaptor port located on the back

ofthe rear cell to connect a 35mm camera body. Attachinga

camera to the NexStar requires the use of the optionalT-

adapter (#93635-A) and a T-ring specificto the brand of

camerabeing u sed. Toat tach the photographic accessories:

1. Remove the screw-on cover from the photo

adaptor port on the rear cell.

2. Thread the T-adapter securely onto the photo

adapter port.

3. Thread the T-ring onto the exposed end of theT-

adapter.

4. Remove any lens from the body of your camera.

5. Attach the camera body to the T-ring by aligning

thered dot on the side of the T-ring with the dot on

thecamera body and twisting.

Beforeattempting photography through your NexStar makesure that the flip mirror is in the "down" position. This

willallow the light path to go straight through the optical tube and pass directly into the camera.

Finding the North Celestial Pole

In each hemisphere, there is a point in the sky around which all the other starsappear

torotate. These points are called the celestial poles and are named for the hemisphere

in which theyreside. For example,in the northernhemisphere all stars move around

the north celestial pole. When the telescope's polar axis is pointed at th e celestial

pole,it is parallel to the Earth's rotational axis.

Manymethods of polar alignment require that you know how to findthe celestial pole

by identifying stars in the area. For those in the northern hemisphere, finding the

celestial pole is not too difficult. Fortunately, we have a naked eye star less than a

degree away. This star, Polaris, is the end star in the h andleof the Little Dipper.

Figure 6-5

Theposition of the Big

Dipperchanges throughout

theyear and the night.

Figure6-4 – NexStar with photographic Accessories

CameraBody

T-Ring T-Ada

ter