Omegon Pro Penta Prism 90° 1.25'' Instruction Manual

1. Product Overview

The Omegon Pro Penta Prism 90° 1.25'' is a high-quality optical accessory designed for use with refractors and catadioptric telescopes. This five-sided prism provides a comfortable 90-degree viewing angle, allowing for relaxed observation. Unlike standard star diagonals, the penta prism produces an image that is inverted (upside down) but not mirrored (left-right correct). This unique image orientation is particularly beneficial when using star charts or lunar maps, as the view through the telescope directly corresponds to the map's orientation, simplifying navigation.

Key features include:

• Natural 90° Viewing Angle: Offers comfortable observation, reducing neck strain during extended viewing sessions.
• Inverted, Non-Mirrored Image: Provides a view that is upside down but correctly oriented left-to-right, aiding in chart-based navigation.
• 29 mm Optical Aperture: Ensures a wide field of view without vignetting, even with longer focal length eyepieces.
• Ultra-Bright Images: High-quality optical coatings deliver clear and bright views.

Image 1.1: Front-side view of the Omegon Pro Penta Prism 90° 1.25''. This image shows the eyepiece holder and the main body of the prism, highlighting its robust construction.

2. Setup and Installation

Follow these steps to correctly install your Omegon Pro Penta Prism:

1. Prepare Your Telescope: Ensure your telescope is securely mounted and balanced. If you are replacing an existing diagonal, carefully remove it from the focuser.
2. Insert the Penta Prism: Slide the chrome barrel of the Omegon Pro Penta Prism into your telescope's 1.25-inch focuser. Gently push it in until it is fully seated.
3. Secure the Prism: Tighten the thumbscrew(s) on your telescope's focuser to hold the penta prism firmly in place. Do not overtighten, as this can damage the barrel.
4. Insert an Eyepiece: Loosen the thumbscrew on the eyepiece holder of the penta prism. Insert your desired 1.25-inch eyepiece into the holder.
5. Secure the Eyepiece: Tighten the thumbscrew on the penta prism's eyepiece holder to secure the eyepiece. Again, avoid overtightening.

Compatibility Note: This penta prism is suitable for use with refractors and catadioptric telescopes (e.g., Schmidt-Cassegrains, Maksutov-Cassegrains). It is generally not recommended for Newtonian reflector telescopes due to potential backfocus issues that may prevent reaching focus.

Image 2.1: Rear-side view of the Omegon Pro Penta Prism 90° 1.25''. This angle shows the connection barrel that inserts into the telescope focuser.

3. Operation

Once installed, using the Omegon Pro Penta Prism is straightforward:

• Focusing: Use your telescope's focuser to achieve a sharp image. The penta prism does not alter the focal length of your telescope.
• Image Orientation: Remember that the image you see through the penta prism will be inverted (upside down) but correctly oriented from left to right. This is different from a standard star diagonal, which typically produces a correctly oriented image that is mirrored left-to-right. This inverted, non-mirrored view is advantageous for comparing the telescopic view with printed star charts or lunar maps, as you only need to rotate the map 180 degrees to match the field of view.
• Eyepiece Rotation: The penta prism allows for 360-degree rotation within the focuser, enabling you to adjust the viewing angle for maximum comfort.

4. Maintenance

Proper care and maintenance will ensure the longevity and optimal performance of your penta prism:

• Cleaning Optical Surfaces:
  1. Use a soft brush or compressed air to remove loose dust particles.
  2. Apply a few drops of optical cleaning fluid to a clean, lint-free microfiber cloth or optical tissue.
  3. Gently wipe the optical surfaces in a circular motion, starting from the center and moving outwards. Avoid excessive pressure.
  4. Do not use abrasive materials or household cleaners, as these can damage the optical coatings.
• Cleaning the Body: Wipe the exterior body of the prism with a soft, damp cloth.
• Storage: When not in use, store the penta prism in its original packaging or a protective case in a dry, dust-free environment. Keep dust caps on both ends to prevent dust accumulation.
• Avoid Disassembly: Do not attempt to disassemble the prism, as this will void the warranty and can lead to damage or misalignment of optical components.

5. Troubleshooting

If you encounter issues with your Omegon Pro Penta Prism, consider the following:

• Cannot Achieve Focus:
  • Ensure the prism is fully inserted into the focuser and secured.
  • Verify that your telescope is compatible with a diagonal. Newtonian reflectors often have insufficient backfocus for diagonals.
  • Try a different eyepiece to rule out eyepiece issues.
• Poor Image Quality / Dim Image:
  • Check if the optical surfaces of the prism and eyepiece are clean. Dust or smudges can significantly degrade image quality.
  • Ensure the eyepiece is fully inserted and secured in the prism's holder.
  • Verify that the telescope's optics are clean and collimated (if applicable).
• Vignetting (Darkening at Image Edges):
  • While the 29mm aperture minimizes vignetting, it can still occur with very wide-field eyepieces or certain telescope designs.
  • Ensure the eyepiece is fully inserted.

If problems persist, consult your telescope's manual or contact Omegon customer support.

6. Specifications

7. Warranty and Support

Warranty: This Omegon Pro Penta Prism 90° 1.25'' comes with a 24-month manufacturer's warranty from the date of purchase. This warranty covers defects in materials and workmanship under normal use. Please retain your proof of purchase for warranty claims.

Exclusions: The warranty does not cover damage caused by misuse, accidental damage, unauthorized repairs, or normal wear and tear.

Customer Support: For technical assistance, warranty claims, or further inquiries, please contact Omegon customer support through their official website or your retailer. Provide your product model number (57292) and a detailed description of the issue when contacting support.