Meade LT Series, LT SC Series, LT ACF Series Appendix D, ACF and SC Optical Systems

Page 49

APPENDIX D:

ACF AND SC OPTICAL SYSTEMS

 

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Ray (2)

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Secondary

 

 

Focal

 

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Plane

 

Secondary

Primary Baffle Tube

 

Baffle

 

 

Field Stops

 

Correcting

 

 

Primary Mirror

 

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The Meade Advanced Coma-Free Optical System

OPTICAL SYSTEMS

Unlike Schmidt-Cassegrain systems, Meade’s Advanced Coma-Free (ACF) optical system provides razor-sharp pin-point star images all the way to the very edge of the field of view. This aplanatic (coma-free) optical system brings the highest level of performance to the amateur astronomer.

In the ACF design of the Meade LT Series, light enters from the right, passes through a thin lens with 2-sided aspheric correction (“correcting plate”), proceeds to a spherical primary mirror, and then to a hyperbolic secondary mirror. The hyperbolic secondary mirror multiplies the effective focal length of the primary mirror and results in a focus at the focal plane, with light passing through a central perforation in the primary

mirror.

All models of the Meade LT includes oversize primary mirrors, yielding a fully illuminated field-of-view significantly wider than is possible with a standard-size primary mirror. Note that light ray (2) in the figure would be lost entirely, except for the oversize primary. It is this phenomenon which results in Meade ACF having off-axis field illuminations about 10% greater, aperture- for-aperture, than other systems utilizing standard-size primary mirrors. Field stops machined into the inside- diameter surface of the primary mirror baffle tube significantly increase lunar, planetary, and deep-space image contrast. These field stops effectively block off- axis stray light rays.

 

(2)

(1)

 

 

(1)

 

(2)

 

 

Ray (2)

Ray (1)

 

 

(2)

 

 

(1)

 

Secondary

 

 

Focal

 

Mirror

 

 

Plane

 

Secondary

Primary Baffle Tube

 

Baffle

 

 

Field Stops

 

Correcting

 

 

Primary Mirror

 

Plate

 

 

The Meade Schmidt-Cassegrain Optical System

In the Schmidt-Cassegrain design of the Meade LT, light enters from the right, passes through a thin lens with 2-sided aspheric correction (“correcting plate”), proceeds to a spherical primary mirror, and then to a convex secondary mirror. The convex secondary mirror multiplies the effective focal length of the primary mirror and results in a focus at the focal plane, with light passing through a central perforation in the primary mirror.

All models of the Meade LT Schmidt-Cassegrain includes oversize primary mirrors, yielding a fully

illuminated field-of-view significantly wider than is possible with a standard-size primary mirror. Note that light ray (2) in the figure would be lost entirely, except for the oversize primary. It is this phenomenon which results in Meade Schmidt-Cassegrains having off-axis field illuminations about 10% greater, aperture-for- aperture, than other Schmidt-Cassegrains utilizing standard-size primary mirrors. Field stops machined into the inside-diameter surface of the primary mirror baffle tube significantly increase lunar, planetary, and deep-space image contrast. These field stops effectively block off-axis stray light rays.

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INDEX

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Contents Index Battery Safety Instructions Contents LT Series ACF and LT Series SC Telescope IntroductionAssembling the Tripod Getting StartedLock-Knob Spreader Shaft End Nut Spreader BarUsing an AC Adapter or DC Power Cord Installing the BatteriesPower Port Mounting the TelescopeYour Telescope is now Fully Assembled Attaching AccessoriesGETTING#497 Handboxstarted Using the Red Dot Finder Adjusting the Red Dot FinderLT Series Home Position Aligning the LT SeriesMagnetic North Home Position True North Home PositionInitializing AutoStar Moving Through AutoStar’s MenusEasy Two-Star Align How to perform the Easy Align ProcedureGo To Saturn Using the Guided TourAutoStarLT SERIES#497KEYHANDBOXFEATURES B. C. D. E Computer Control Panel Eyepiece Holder Thumb ScrewChoosing Eyepieces Optional Accessories52º AutoStarOPTIONAL#497ACCESSORIESHANDBOX Imagers and Accessories Power SuppliesTour the Cosmos with Just the Push of a Button AUTOAutotarSTAR#497HANDBOXSlew Speeds Observing Using AutoStar’s Arrow Keys Terrestrial Observing Observe the MoonTo Calculate Sunset time AutoStar Navigation ExerciseGuided Tour Menu Entering Data into AutoStarObject Menu Navigating AutoStarAutoStar #497 Menu Tree Event Menu Utilities Menu Glossary MenuSetup Menu Index Autostar #497 Handbox To Add a Site to the user-defined site list Adding Observing SitesTo Edit a Site To GO to a user-entered object Using AutoStar to Find Objects Not in the DatabaseObserving Satellites Tour Modes How to Create Your Own Guided TourWriting a Tour Command LineComment Line Index Downloading Tours LandmarksTo Select a landmark from the database To Add a landmark to the databaseTo perform a Landmark Survey To check on the available amount of memory in AutoStarAdvanced Alt/Az Alignment IdentifyTwo-Star Alt/Az Alignment Displayed information ExampleAutostar Features One-Star Alt/Az Alignment BrowseCollimation MaintenanceLT Series Collimation Collimation ScrewsInspecting the Optics Customer ServiceGauging the Movement of the Telescope Updating Your LT Series FirmwareAppendix a DriveObjects in Space Appendix BDeep-Sky Objects Model and Product Number LT ACF # Optical System Appendix C SpecificationsAutoStarSPECIFICATIONS#497 Handbox ACF and SC Optical Systems Appendix DFederal Communications Commission Appendix ERecycling 55-09004 Meade Limited Warranty

LT Series, LT ACF Series, LT SC Series specifications

The Meade LT SC Series, LT ACF Series, and LT Series telescopes are designed to meet the diverse needs of amateur astronomers and astrophotographers alike. Each of these series caters to various levels of experience while incorporating advanced features and technologies that enhance observational stability and image quality.

The Meade LT SC Series, featuring the advanced Schmidt-Cassegrain design, excels in versatility. This series includes different aperture sizes, allowing users to view celestial objects ranging from the moon to distant galaxies. The telescopes come equipped with an AudioStar hand controller that provides a database of over 30,000 celestial objects, enabling users to easily locate and track their subjects. The built-in GPS feature facilitates effortless alignment by automatically determining the user’s location and time.

In contrast, the LT ACF Series showcases Meade's innovative Advanced Coma-Free (ACF) optics. This design minimizes coma and field curvature, providing sharp, crisp images across a wider field of view. Ideal for astrophotography, this series is enhanced by features like a fast focal ratio for better imaging of dim objects and a robust construction that ensures stability during use. The LT ACF telescopes also support advanced imaging techniques, allowing users to capture stunning images of deep-sky objects while minimizing aberrations.

The classic LT Series remains a favorite among beginners. Known for its straightforward setup and usability, this series is designed with a lightweight and portable frame. The LT Series telescope is equipped with an altazimuth mount, making it user-friendly for quick observations. The simplicity allows new astronomers to start observing with minimal technical knowledge. Additionally, these telescopes support a variety of accessories such as smartphone adapters, making it easy for users to capture their observations.

All three series incorporate Meade's proprietary StarLock technology in certain models, which facilitates automated tracking. This feature frees astronomers from the complexities of manual tracking, allowing them to focus more on the experience of observing celestial wonders.

In summary, the Meade LT SC Series, LT ACF Series, and LT Series deliver exceptional optical performance and user-friendly features, making them suitable for a wide range of astronomy enthusiasts. Whether you are a seasoned astrophotographer or a novice sky-watcher, Meade's telescopes provide the technology and capabilities needed to explore the universe.
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