Celestron 8i manual Eyepiece Projection, Full

Page 35

•T-Max 100

•T-Max 400

•Any 100 to 400 ISO color slide film

•Fuji Super HG 400

•Ektar 25 or 100

2.Center the Moon in the field of your NexStar 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 below).

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 NexStar telescope.

The exposure times listed in table 6-1 should be used as a starting point. Always make exposures that are longer and shorter than the recommended time. Also, take a few photos at each shutter speed. This will ensure that you will get a good photo.

If using black and white film, try a yellow filter to reduce the light intensity and to increase contrast.

Keep accurate records of your exposures. This information is useful if you want to repeat your results or if you want to submit some of your photos to various astronomy magazines for possible publication!

This technique is also used for photographing the Sun with the proper solar filter.

Eyepiece Projection

This form of celestial photography is designed for objects with small angular sizes, primarily the Moon and planets. Planets, although physically quite large, appear small in angular size because of their great distances. Moderate to high magnification is, therefore, required to make the image large enough to see any detail. Unfortunately, the camera/telescope combination alone does not provide enough magnification to produce a usable image size on film. In order to get the image large enough, you must attach your camera to the telescope with the eyepiece in place. To do so, you need two additional accessories; a deluxe tele-extender (#93643), which attaches to the visual back, and a T-ring for your particular camera make (i.e., Minolta, Nikon, Pentax, etc.).

Because of the high magnifications during eyepiece projection, the field of view is quite small which makes it difficult to find and center objects. To make the job a little easier, align the finder as accurately as possible. This allows you to get the object in the telescope's field based on the finder's view alone.

Another problem introduced by the high magnification is vibration. Simply tripping the shutter even with a cable release produces enough vibration to smear the image. To get around this, use the camera's self- timer if the exposure time is less than one second a common occurrence when photographing the Moon. For exposures over one second, use the "hat trick." This technique incorporates a hand-held black card placed over the aperture of the telescope to act as a shutter. The card prevents light from entering the telescope while the shutter is released. Once the shutter has been released and the vibration has diminished (a few seconds), move the black card out of the way to expose the film. After the exposure is complete, place the card over the front of the telescope and close the shutter. Advance the film and you're ready for your next shot. Keep in mind that the card should be held a few inches in front of the telescope,

36

Page 34 Page 36
Image 35
Page 34 Page 36
Contents Page Hand Control Operation Alignment Procedures Care and Cleaning of the Optics Collimation Page NexStar 8i SE StarPointer Finderscope Eyepiece Diagonal Visual Back Appendix C Longitude Latitude Mounting the Telescope to the Tripod Assembling the NexStarStar Diagonal Powering the NexStarHand Control Star Pointer Finderscope Star Pointer InstallationEyepiece Star Pointer Operation NexStar Computerized Hand Control Double Stars Hand Control OperationAuto Two-Star Align Alignment ProceduresTwo Star Alignment Selecting an Object Object CatalogEQ North / EQ South Alignment NexStar Re-AlignmentSlewing to an Object Tour ModeFinding Planets Rate Button Setup ProceduresDirection Buttons Page Menu Scope Setup FeaturesUtility Features Helpful Hint NexStar Ready Image Orientation Determining Field of View FocusingCalculating Magnification General Observing Hints Celestial Coordinate System Motion of the Stars Wedge Align Polar Alignment with optional WedgeFinding the North Celestial Pole Lunar Observing Hints Observing the MoonObserving the Planets Observing the SunSky Illumination Observing Deep Sky ObjectsSeeing Conditions TransparencyPage Short Exposure Prime Focus Photography Full Eyepiece ProjectionPlanet ISO Moon Mercury Venus Mars Jupiter Saturn Long Exposure Prime Focus PhotographyPage Reducing Vibration Terrestrial PhotographyCCD Imaging MeteringCollimation Care and Cleaning of the OpticsCollimated telescope Should appear Symmetrical with Page Adapter, Car Battery #18769 Page Page Appendix a Technical Specifications Page Appendix B Glossary of Terms Trillion km 5.87 X 1 trillion mi Right Ascension RA Appendix C Longitudes Latitudes Georgia Minnesota Rhode Island Canada Communication Protocol Appendix D RS-232 ConnectionAppendix E Maps of Time Zones Page Page Page Page Page Page Page Celestron TWO Year Warranty

8i specifications

The Celestron 8i is a highly regarded telescope that has made a significant impact in the world of amateur astronomy, renowned for its performance, advanced features, and user-friendly design. Part of Celestron's Advanced Series, the 8i model boasts an impressive 8-inch Schmidt-Cassegrain optical system, which combines the advantages of a large aperture with a compact design. This allows enthusiasts to explore celestial objects with greater clarity, providing bright, sharp images of planets, star clusters, and nebulae.

One of the standout features of the Celestron 8i is its Fast Star capability, which allows for rapid imaging of celestial objects. Coupled with its advanced StarBright XLT coatings, this system enhances light transmission and increases contrast, resulting in a more vivid and detailed observation experience. This combination makes it an ideal choice for both novice and experienced astronomers who seek high-quality visuals of deep-sky objects.

The telescope's computer-controlled GoTo mount simplifies the process of locating and tracking celestial objects. With the push of a button, users can easily access a database containing over 40,000 astronomical objects, allowing for an effortless stargazing experience. The Celestron 8i also features an intuitive hand controller that enables users to customize their observations and seamlessly navigate the night sky.

The Celestron 8i is designed for portability, despite its robust optical performance. Weighing in at around 45 pounds, it is relatively easy to transport to different observing locations. The telescope's sturdy construction ensures stability while providing ease of setup, facilitating a hassle-free stargazing experience.

In terms of accessories, the 8i comes equipped with a 25mm eyepiece, offering a moderate magnification that is perfect for a variety of targets. Additionally, users can expand their observing capabilities with optional eyepieces, filters, and focal reducers, catering to both visual and astrophotography pursuits.

Overall, the Celestron 8i stands out as a versatile and powerful telescope that meets the needs of amateur astronomers at various skill levels. With its advanced features, superior optics, and impressive usability, the 8i offers a unique and rewarding experience under the night sky. Whether for planetary observation or deep-sky exploration, the Celestron 8i remains a top choice for astronomy enthusiasts.
Top Page Image Contents