Orion 90 - User Manual

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Summary

Introduction and Initial Setup

Parts List

Lists all components included with the telescope for user verification.

Getting Started

Provides initial instructions for setting up and using the telescope.

Telescope Installation and Usage

Installing Accessories

Guidance on attaching the finder scope, diagonal, and eyepiece.

Mounting the Telescope

Instructions for attaching the telescope to a tripod or mount.

Focusing

Details on how to achieve a sharp image using the focuser.

Aligning the Finder Scope

Steps to accurately align the finder scope with the main telescope.

Viewing Modes and Techniques

Terrestrial Viewing

Tips for observing objects on Earth, including diagonal recommendations.

Astronomical Viewing

Guidance for observing celestial objects and selecting viewing sites.

Calculating Magnification

Formula and advice for determining telescope magnification power.

Photography

Instructions for using the telescope for photography with a camera.

Maintenance, Specifications, and Support

Care & Maintenance

Recommendations for cleaning, storing, and maintaining the telescope.

Specifications

Technical details and measurements of the telescope.

Suggested Accessories

List of recommended optional accessories for enhanced use.

Warranty Information

Details on the one-year limited warranty coverage and service.

Summary

Introduction and Initial Setup

Parts List

Lists all components included with the telescope for user verification.

Getting Started

Provides initial instructions for setting up and using the telescope.

Telescope Installation and Usage

Installing Accessories

Guidance on attaching the finder scope, diagonal, and eyepiece.

Mounting the Telescope

Instructions for attaching the telescope to a tripod or mount.

Focusing

Details on how to achieve a sharp image using the focuser.

Aligning the Finder Scope

Steps to accurately align the finder scope with the main telescope.

Viewing Modes and Techniques

Terrestrial Viewing

Tips for observing objects on Earth, including diagonal recommendations.

Astronomical Viewing

Guidance for observing celestial objects and selecting viewing sites.

Calculating Magnification

Formula and advice for determining telescope magnification power.

Photography

Instructions for using the telescope for photography with a camera.

Maintenance, Specifications, and Support

Care & Maintenance

Recommendations for cleaning, storing, and maintaining the telescope.

Specifications

Technical details and measurements of the telescope.

Suggested Accessories

List of recommended optional accessories for enhanced use.

Warranty Information

Details on the one-year limited warranty coverage and service.

The Orion ShortTube 90 is a 90mm rich-field refracting telescope, model #9069, designed for both daytime terrestrial viewing and nighttime stargazing. It is a compact, portable, and versatile instrument suitable for family use.

Function Description:

The ShortTube 90 serves as a general-purpose telescope, offering bright, expansive views of star fields and celestial objects due to its 90mm unobstructed aperture and short 500mm focal length (f/5.6). For terrestrial viewing, it provides clear images of distant objects. The telescope is equipped with a precision rack-and-pinion focuser for sharp image adjustment. Its 6x30 achromatic finder scope aids in locating subjects by offering a wider field of view, though images in the finder scope will appear upside down, which is normal for astronomical use. The telescope can be mounted on any standard camera tripod with a 1/4"-20 stud, or on an equatorial mount for easier tracking of celestial objects.

Important Technical Specifications:

Objective Lens: 90mm aperture, achromatic air-spaced doublet, fully antireflection coated.
Focal Length: 500mm.
Focal Ratio: f/5.6.
Optical Tube Assembly Weight: 5 lbs.
Mounting Provision: 1/4"-20 threaded mounting block.
Finder Scope: 6x magnification, 30mm aperture, achromatic, with crosshairs.
Eyepiece: 26mm (19x) Plössl, 1.25" barrel diameter, fully coated.
Diagonal: 90° star diagonal, mirror-type, 1.25" barrel diameter.
Magnification Calculation: Magnification = Telescope Focal Length (mm) / Eyepiece Focal Length (mm). For the included 26mm eyepiece, this yields 500mm / 26mm = 19x.
Useful Power Limit: Approximately 45x-60x per inch of aperture.

Usage Features:

Setup: The telescope comes nearly fully assembled. Users need to slide the 6x30 finder scope into its bracket and tighten the alignment screws, then insert the 90° star diagonal and eyepiece into the focuser drawtube and secure them.
Mounting: It can be attached to any standard camera tripod or an equatorial mount. An equatorial mount is recommended for astronomical viewing to easily track celestial objects.
Focusing: The rack-and-pinion focuser allows users to achieve sharp images by gently turning the large focusing wheels. The focus lock setscrew must be loosened before adjusting focus.
Finder Scope Alignment: The finder scope must be precisely aligned with the main telescope. This is done in daylight by centering a distant object in both the main eyepiece and the finder scope's crosshairs using the six alignment screws.
Terrestrial Viewing: For correctly oriented images, an optional 45° correct-image diagonal (Orion part #8790) is recommended instead of the standard 90° star diagonal, which reverses left-to-right. An altazimuth-style camera tripod or telescope mount (e.g., Orion Paragon HD-F2 or AZ-3 mount) is suitable for simple vertical and horizontal motions.
Astronomical Viewing: The ShortTube 90 is excellent for observing star fields, the Moon, planets (Jupiter, Saturn, Venus, Mars), stars, and brighter deep-sky objects. For optimal viewing, it's recommended to observe from dark-sky locations and allow eyes to dark-adapt for at least 20 minutes. A red flashlight (e.g., Orion RedBeam LED Flashlight) is useful for preserving night vision. Familiarity with the night sky using a planisphere or star chart (e.g., Orion DeepMap 600) is advised for locating objects.
Eyepiece Selection: Always start viewing with the lowest-power eyepiece (longest focal length). Higher-power eyepieces can be used for more detail if atmospheric conditions permit, but they will result in dimmer and less sharp images.
Eyeglass Use: Users wearing eyeglasses may keep them on if their eyepieces offer sufficient "eye relief" to view the full field. Otherwise, glasses can be removed, and the telescope refocused.
Astrophotography: With appropriate adapters (T-ring for the camera and a 1.25" Universal Camera Adapter), the ShortTube 90 becomes a 500mm f/5.6 telephoto lens for a 35mm SLR camera. For astrophotography, the telescope with camera attached should be mounted on an equatorial mount with at least one motor drive to track stars. A remote shutter release and a solid tripod are recommended to prevent vibrations.
Solar Viewing Warning: Never look at the sun with the telescope (or even with just your eyes) without a professionally made solar filter that covers the front of the telescope. Avoid eyepiece-threaded solar filters due to risk of cracking and severe retinal damage. The finder scope should also be covered with an opaque material.

Maintenance Features:

Storage: Store the telescope indoors or in a dry garage. Keep the original shipping box for storage and potential warranty service.
Cleaning:
- Optical Tube: Smudges can be wiped off with standard household cleaners like Windex. Scratches on the tube will not harm the telescope and can be touched up with white auto touch-up paint.
- Lenses (Objective, Eyepieces, Finder Scope): Use only quality optical lens tissue and cleaning fluid specifically designed for multi-coated optics. Never use regular glass cleaner. Before applying fluid, blow off loose particles with a blower bulb or compressed air, or lightly brush with a soft camel hair brush. Apply fluid to a tissue, not directly to the optics, and wipe gently in a circular motion. Use a fresh tissue for excess fluid. For larger lenses, clean a small area at a time with a fresh tissue.
- Disassembly: Do not disassemble the telescope, eyepieces, or other optical components, as this will void the warranty. Cleaning of inaccessible optical surfaces should be performed by experienced opticians.
Warranty: The Orion ShortTube 90mm Refractor comes with a one-year limited warranty against defects in materials or workmanship from the date of purchase. This warranty is for the original retail purchaser only and requires proof of purchase. It does not cover abuse, mishandling, modification, or normal wear and tear.