How does the Howie Glatter 635nm collimator maintain its alignment so well?
Each collimator undergoes a rigorous shock-testing procedure at the factory. After its initial alignment to 15 arc-seconds, the unit is struck at least a dozen times on three different axes. The alignment is then rechecked to ensure it has not shifted, and the collimators withstand a shock equivalent to a drop from eyepiece position up the ladder on a big Dob.
What is the purpose of the included 1mm aperture stop?
The aperture stop is used to increase collimation accuracy. It push-fits into the laser aperture and transforms the standard fuzzy, elliptical laser dot into a tiny, circular beam. This makes it much easier to judge the exact center of the beam on your primary mirror's center marking. The resulting beam also creates a diffraction pattern that can be used for even finer centering adjustments.
Can I use the Howie Glatter single-beam laser to collimate my Newtonian without a center spot on the primary?
No, for a single-beam laser collimator, a center spot or ring on the primary mirror is essential. The process requires you to adjust the secondary mirror until the laser beam hits the exact center of the primary. Without a reference mark, it is impossible to judge this alignment accurately by eye. A holographic attachment (sold separately) allows secondary adjustment without a center dot, by making the pattern symmetrical at the edge of the primary.
How do I safely use this Howie Glatter laser collimator with my refractor?
Safety is critical. The laser beam will always exit the front of a refractor. Before you begin, place a strip of masking tape across the opening of the dew shield to act as a beam stop. This prevents the Class IIIa laser beam from exiting the telescope. Always avoid direct or mirror-reflected eye exposure to the beam.
When should I choose the 635nm Howie Glatter collimator over the 650nm version?
Choose this 635nm model if you often collimate in brighter conditions, such as during twilight. Its beam appears two to three times brighter to the eye, making it much easier to see. For collimation in complete darkness, the standard 650nm laser is sufficient and perfectly adequate for single-beam use.