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Howie Glatter Uni-Blug Newtonian Collimator - 2"
The Howie Glatter Uni-Blug is a specialized tool for precisely aligning the primary mirror of a Newtonian telescope, designed to fit inside a 2" focuser drawtube. It uses an integrated Barlow lens to project the shadow of your primary mirror's center mark onto a matte-white 45° screen, providing an intuitive and accurate reference for adjustment. It extends 3/8" into the inner end of the drawtube, so the laser collimator in the eyepiece end must not reach forward far enough to touch it.
Barlowed Collimation: Using a 45° Screen for Primary Alignment
The Uni-Blug simplifies the final, most critical step of Newtonian collimation. After aligning your secondary mirror with a single-beam laser, you insert the Uni-Blug into the inner end of the focuser drawtube. The laser beam passes through the Blug's anti-reflection coated Barlow lens, diverging to illuminate the primary mirror's center.
The primary mirror reflects this light back as a collimated beam containing a crisp shadow of its center marking. This shadow is projected onto the Uni-Blug's 45° screen, where its position directly indicates the primary's alignment. You then adjust your primary mirror's collimation screws until the shadow is perfectly centered on the screen's central aperture, completing the alignment.
Universal Fit for 2" Focusers: Feather Touch Compatibility
This "Uni-Blug" design consolidates the previous separate BLUG and FLUG models into a single, universal tool. It fits the inner end of the focuser drawtube, retained by an O-ring in its base. Drawtube inner ends vary between focuser makers, although most are near eyepiece nominal size.
For use with 2" Crayford Feather Touch focusers, which have a larger internal diameter at the drawtube end, a shim kit is included. By placing the thin gray or thick brown shim under the O-ring, you get a snug fit; if the Uni-Blug feels loose or tilts with the gray shim, change to the brown one.
3/8" Insertion Depth: A Step-by-Step Collimation Guide
Using the Uni-Blug is a straightforward process. First, ensure your secondary mirror is aligned using your laser collimator alone. Before inserting the Blug, remove any aperture stop from your laser collimator to ensure a high-contrast shadow without diffraction rings. Insert your laser collimator into the focuser first to prevent air pressure from dislodging the Blug.
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Insertion: The Uni-Blug inserts just 3/8" into the drawtube. Ensure your laser collimator does not protrude far enough to make contact with it.
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Truss-Tube Scopes: Orient the 45° screen to face the rear of the telescope, making it visible while you are at the primary mirror making adjustments.
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Solid-Tube Scopes: Turn the Uni-Blug 180° so the screen faces the front of the telescope, allowing you to view it from the front while adjusting the primary.
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What is the difference between this 2" Uni-Blug and older Howie Glatter models?
The Uni-Blug combines the functions of the previous, separate BLUG (for standard focusers) and FLUG (for Feather Touch focusers) into one tool. This model includes shims to adapt its fit for the larger inner diameter of 2" Feather Touch drawtubes, making it a universal solution.
How do I use the shims with my 2" Feather Touch focuser and the Uni-Blug?
You must place a shim into the O-ring groove on the Uni-Blug's base. Two shims are provided: a thinner gray one and a thicker brown one. Start by installing the gray shim under the O-ring and test the fit. If the Uni-Blug still feels loose or tilts inside the drawtube, replace the gray shim with the thicker brown one for a secure fit.
Why must I remove my laser collimator's aperture stop when using the Uni-Blug?
The aperture stop, used for precise secondary alignment, will cause the Barlowed laser shadow to lose contrast and may create confusing diffraction rings on the Uni-Blug's screen. Removing it ensures you see a sharp, high-contrast silhouette of the primary's center mark, which is essential for accurate alignment.
On my solid-tube Newtonian, which way should the Uni-Blug's screen face?
For a solid-tube scope, insert the Uni-Blug so its 45° screen faces the front opening of the telescope. The target shadow is then easily seen from the front of the scope.
Can I align my secondary mirror with the Howie Glatter Uni-Blug?
No. The Uni-Blug is designed exclusively for aligning the primary mirror. You must first align your secondary mirror's tilt using a single-beam laser collimator by itself, ensuring the laser dot hits the center of the primary mirror. Only then do you insert the Uni-Blug to perform the final primary alignment.
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| Type |
Barlowed collimation plug (Uni-Blug) for Newtonian primary mirror alignment |
| Fits |
Inner end of the focuser drawtube, Feather Touch and non-Feather Touch focusers (2") |
| Screen |
Matte-white 45° face |
| Lens |
Small anti-reflection coated Barlow lens in a central axial hole |
| Retention |
O-ring in the base |
| Depth Into Drawtube |
3/8" |
| Use With |
A single-beam laser collimator, after the secondary is aligned |
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Shims for 2" Feather Touch focusers (gray thin, brown thick)
× 1
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Howie Glatter Warranty
