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Howie Glatter Holographic Attachment w/ Concentric Circle Pattern

Howie Glatter Holographic Attachment w/ Concentric Circle Pattern

by Howie Glatter
SKU SI-HOLA-Circle
CA$154.00 - CA$154.00
CA$154.00
CA$154.00 - CA$154.00
CA$154.00
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  • Projects a pattern of 9 concentric circles
  • 10° pattern spread ideal for f/5.7 and slower optics
  • Brighter pattern is ideal for Cassegrain collimation
  • Removable attachment with 3/8-32 thread
  • Fits current-generation Howie Glatter laser collimators
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  • Description
  • FAQ
  • Specifications
  • In the Box
  • Warranty

  • Howie Glatter Holographic Attachment w/ Concentric Circle Pattern

    The Howie Glatter Holographic Attachment with Concentric Circle Pattern transforms a single-beam laser collimator into a precision alignment tool, projecting a pattern of 9 concentric circles across a 10° spread. This removable diffractive optical element is recommended for Cassegrain telescopes and scopes around f/5.7 or slower, attaching via the 3/8-32 thread to modern Howie Glatter laser collimators.

    9 Concentric Circles: A 10° Pattern for Slower Optics

    This attachment diffracts the laser beam into a symmetrical pattern of 9 concentric circles, providing a clear visual reference for centering optical elements. The pattern's 10° spread is engineered to reach the edge of primary mirrors in telescopes with focal ratios of f/5.7 and slower, making it a specialized tool for precise alignment in these systems.

    The key advantage of the concentric circle pattern is its brightness. By concentrating the laser's light into a smaller area compared to a grid pattern, it produces a more intense projection. This is critical for Cassegrain collimation, where the pattern's visibility on the mirror surface depends on light scattered from dust or optical roughness; a brighter pattern is better, especially if the mirrors are very clean.

    Removable 3/8-32 Thread Design for Modern Glatter Collimators

    Designed as a modular accessory, this holographic attachment threads directly onto the front of any current-generation Howie Glatter laser collimator using the 3/8-32 thread. You can easily unscrew the attachment to revert to a standard single-beam laser for tasks like primary mirror alignment in a Newtonian, then reinstall it to retain holographic capability.

    Each holographic attachment is individually fitted to a collimator during manufacturing to ensure maximum alignment accuracy. While the attachment can be physically moved between different collimators, doing so may compromise the holographic mode's high precision. This is a critical trade-off: for the most accurate results, the attachment should remain dedicated to a single laser collimator body.

    Concentric Circle vs. Square Grid: Choosing the Right Pattern

    The primary alternative to the concentric circle attachment is Howie Glatter's square grid pattern. The square grid offers a much wider 21° spread, making it the superior choice for collimating very fast Newtonians with focal ratios down to f/2.7. Its pattern is designed for general-purpose use across a wide variety of telescope designs.

    You should choose the Concentric Circle attachment specifically for its advantages in slower systems. Its narrower 10° spread creates a brighter, more concentrated pattern that is easier to see on the mirror surfaces of Cassegrain telescopes, where the pattern impact is sometimes scrutinized on the mirror.

  • Will the Howie Glatter Concentric Circle attachment fit my older laser collimator?

    This attachment is designed for current-generation Howie Glatter laser collimators that use the coarser 3/8-32 thread, identified by a visible ring. It will not fit older models that used a finer 5/16-56 thread.

    How do I use the Concentric Circle attachment to collimate my 8" f/10 SCT?

    With the collimator in the visual back (no diagonal), check that the circles are centered on the secondary. On a commercial SCT only the secondary tilt is adjustable; find its best setting with a star test at high power, then record where the return beam lands on the collimator face in single-beam mode (diffractor removed), so you can return the secondary to it any time.

    Why is this Concentric Circle attachment recommended for Cassegrains over the square grid?

    The concentric circle pattern is brighter. Its 10° spread concentrates the laser's light over a smaller area than the square grid's wide pattern. In a Cassegrain, the pattern is viewed on the mirror surface via scattered light, so a brighter pattern is much easier to see, especially if your optics are very clean.

    Is the Concentric Circle attachment useful for my f/4 Dobsonian?

    No, this pattern is not the correct tool for a fast Newtonian. The 10° pattern spread is too narrow and is optimized for optics at f/5.7 and slower. For an f/4 Dobsonian, the Howie Glatter square grid attachment is the recommended tool, as its wider pattern is designed to work with optics as fast as f/2.7.

    Can I swap this Concentric Circle attachment with a friend's square grid attachment?

    While they will physically thread on, it is not recommended. Howie Glatter holographic attachments are individually aligned to their collimator bodies at the factory for maximum precision. Swapping attachments between different collimators will likely degrade the alignment accuracy in holographic mode.

  • Pattern 9 concentric circles
    Spread 10°
    Optics Covered f/5.7 and slower
    Brightness Brighter than the square grid (light spread over a smaller area)
    Recommended For Cassegrain telescopes and scopes around f/5.7 or slower
    Type Removable diffractive optical element (hologram)
    Fits Howie Glatter laser collimators, current 3/8-32 thread

    • Concentric circle holographic attachment

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  • Howie Glatter Warranty