ORION TELESCOPES & BINOCULARS 8893

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Summary

Orion Field Flattener for Short Refractors

Attaching to DSLR Camera

Details how to connect the field flattener to DSLR cameras using T-rings for optimal focus.

Attaching to Astronomical CCD;CMOS Camera

Explains connecting the flattener to CCD/CMOS cameras, including the use of spacers for proper distance.

Care and Maintenance Guide

Provides essential instructions for cleaning and storing the field flattener to maintain its performance.

Product Specifications

Lists key technical parameters such as optics, clear aperture, focal length, mechanical profile, and weight.

One-Year Limited Warranty Information

Outlines the terms and conditions of the product's limited warranty, including coverage and exclusions.

The Orion Field Flattener for Short Refractors, model #8893, is an optical accessory designed to correct Petzval field curvature in short refractor telescopes. This correction is crucial for achieving sharp stars across the entire image frame, especially when using cameras with APS-C and full-size sensors, without altering the refractor's focal length.

Function Description:

The primary function of the Orion Field Flattener is to ensure that the periphery of the image frame remains in focus, addressing the common issue of slight defocus at the edges caused by Petzval field curvature. This is achieved through its doublet optical lens configuration, which provides the necessary correction for a consistently sharp image. The device is designed to fit into 2" focuser drawtubes and its barrel is internally threaded to accept 2" Orion filters.

Important Technical Specifications:

Optics: 2-element, fully-multicoated. This multi-coating helps to reduce reflections and increase light transmission, resulting in brighter, higher-contrast images.
Clear Aperture: 38mm. This refers to the effective diameter of the optical element that allows light to pass through.
Focal Length: 55mm. This specification is crucial for understanding the backfocus requirements.
Mechanical Profile: 51mm. This dimension likely refers to the overall length or a significant mechanical measurement of the flattener body.
Camera Attachment: Male M42 and M48 interchangeable adapters. The inclusion of both standard T-thread (M42) and "wide" T-thread (M48) adapters provides versatility for connecting various cameras. The M48 adapter is specifically recommended for use with full-frame camera sensors, which benefit from the wider aperture to avoid vignetting.
Weight: 192g (6.8 oz). This indicates a relatively lightweight design, which is beneficial for maintaining the balance of the telescope setup.
Backfocus Distance: The Field Flattener has a critical 55mm backfocus distance. This means that the camera's sensor must be positioned exactly 55mm behind the Flattener's T-thread flange to achieve optimal focus and full effectiveness.

Usage Features:

The Field Flattener is designed for straightforward attachment to both DSLR and astronomical CCD/CMOS cameras.

Attaching to a DSLR Camera: To attach the Field Flattener to a DSLR camera, an appropriately sized T-ring (M42 or M48, depending on the chosen adapter) for the specific camera make and model is required. The design ensures a perfect match: the distance from the camera's sensor to the front plane of the T-ring is typically 55mm, directly matching the Field Flattener's backfocus distance. This simplifies the setup process for DSLR users, often requiring no additional spacers.
Attaching to an Astronomical CCD/CMOS Camera: Astronomical CCD or CMOS cameras often have different backfocus requirements, typically less than 55mm. In these cases, users will need to add spacers between the camera and the Field Flattener to achieve the precise 55mm backfocus distance. For example, if a camera has a 20.1mm backfocus, approximately 35mm of spacer length would be needed (20.1mm + 35mm = 55.1mm). T-thread spacers are widely available from astronomical equipment dealers. The camera's nosepiece (if equipped) should be removed, and the camera body should be threaded directly onto the back of the Field Flattener or the T-thread spacer. While the Field Flattener will still function if the 55mm distance is not perfectly met, its effectiveness will gradually diminish the farther the camera is positioned from this optimal point in either direction. The CCD/CMOS camera must have compatible female T-threads (usually M42) on its body for attachment.

Maintenance Features:

Proper care and maintenance are essential to preserve the optical quality and longevity of the Orion Field Flattener.

Protection: When not in use, the Field Flattener should be kept in a protected environment. Always place the dust cap and threaded metal cap on the device for storage to prevent dust accumulation and potential damage.
Handling: Avoid touching the glass lenses and their coatings, as fingerprints and oils can degrade optical performance.
Cleaning: If the lenses become dirty, a specific cleaning procedure should be followed:
1. Remove Loose Dirt: First, use a blower bulb to gently blow off any loose dirt or dust particles from the lens surface. This prevents scratching during the wiping process.
2. Wet Wipe: Use only optical lens tissue and high-quality lens fluid. Wet a folded piece of lens tissue with the fluid.
3. Gentle Wipe: Gently wipe the surface of the lens with the wet tissue.
4. Dry Wipe: Immediately use a second, clean piece of lens tissue to gently dry the lens off.
5. Caution: It is crucial not to rub or apply pressure during cleaning, as this could scratch the lens if any dust or grit remains.

The Orion Field Flattener is a valuable accessory for astrophotographers using short refractors, ensuring high-quality, sharp images across the entire field of view. Its robust design, interchangeable adapters, and clear backfocus requirements make it a versatile and effective tool for enhancing imaging results.