Celestron 8i manual Terrestrial Photography, CCD Imaging, Metering, Reducing Vibration

Page 38

Terrestrial Photography

Your NexStar 8i makes an excellent 2000mm telephoto lens for terrestrial (land) photography (The NexStar 5i would be equivalent to a 1250mm lens). Terrestrial photography is best done will the telescope in Alt-Az configuration and the tracking drive turned off so that objects will remain in your camera's field of view.

Metering

The NexStar has a fixed aperture and, as a result, fixed f/ratios. To properly expose your subjects photographically, you need to set your shutter speed accordingly. Most 35mm SLR cameras offer through- the-lens metering which lets you know if your picture is under or overexposed. Adjustments for proper exposures are made by changing the shutter speed. Consult your camera manual for specific information on metering and changing shutter speeds.

Reducing Vibration

Releasing the shutter manually can cause vibrations, producing blurred photos. To reduce vibration when tripping the shutter, use a cable release. A cable release keeps your hands clear of the camera and lens, thus eliminating the possibility of introducing vibration. Mechanical shutter releases can be used, though air- type releases are best.

Blurry pictures can also result from shutter speeds that are too slow. To prevent this, use films that produce shutter speeds greater than 1/250 of a second when hand-holding the lens. If the lens is mounted on a tripod, the exposure length is virtually unlimited.

Another way to reduce vibration is with the Vibration Suppression Pads (#93503). These pads rest between the ground and tripod feet. They reduce the vibration amplitude and vibration time.

CCD Imaging

CCD Imaging is the most challenging form of astro photography and involves the use of a CCD (Charged Coupled Device) camera attached to the telescope at prime focus. The benefits of CCD imaging is the extreme light sensitivity of the electronic chip inside the camera. This allows you to record much fainter detail in a shorter period of time than would be possible with film photography. Due to the relative small size of the CCD chip, the field of view when imaging will be less than the field of view of a film camera. Using Celestron's optional f/6.3 Reducer/Corrector accessory in conjunction with a CCD camera (or film camera) will greatly increase the photographic field of view and will make finding and tracking a celestial object much easier.

39

Page 37 Page 39
Image 38
Page 37 Page 39
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 Assembling the NexStar Mounting the Telescope to the TripodStar Diagonal Powering the NexStarHand Control Star Pointer Finderscope Star Pointer InstallationEyepiece Star Pointer Operation NexStar Computerized Hand Control Hand Control Operation Double StarsAlignment Procedures Auto Two-Star AlignTwo Star Alignment NexStar Re-Alignment Object CatalogEQ North / EQ South Alignment Selecting an ObjectSlewing to an Object Tour ModeFinding Planets Rate Button Setup ProceduresDirection Buttons Page Scope Setup Features MenuUtility Features Helpful Hint NexStar Ready Image Orientation Determining Field of View FocusingCalculating Magnification General Observing Hints Celestial Coordinate System Motion of the Stars Polar Alignment with optional Wedge Wedge AlignFinding the North Celestial Pole Observing the Sun Observing the MoonObserving the Planets Lunar Observing HintsTransparency Observing Deep Sky ObjectsSeeing Conditions Sky IlluminationPage Short Exposure Prime Focus Photography Eyepiece Projection FullLong Exposure Prime Focus Photography Planet ISO Moon Mercury Venus Mars Jupiter SaturnPage Metering Terrestrial PhotographyCCD Imaging Reducing VibrationCare and Cleaning of the Optics CollimationCollimated 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 Appendix D RS-232 Connection Communication ProtocolAppendix 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