Once the curves match the target radii using spherometers, the elements are polished using optical pitch and cerium oxide. Testing is handled through a classic or a monochromatic Ronchi screen setup modified for refractive optics. Remer's documentation outlines how to isolate individual surface errors during these tests. 4. The Air Gap vs. Oil-Spacing Decision
Hours spent pushing glass against glass, the slurry of silicon carbide singing a gritty song of progress [3, 4].
No central obstruction (secondary mirror) means maximum contrast for planetary and lunar viewing.
incoming light —> [ Crown Glass ] (Air Gap / Oil) [ Flint Glass ] —> Focused Image making a refractor telescope norman remer pdf 12 new
: Remer explains the physics behind the craft, such as why a mirror surface must be figured four times as accurately as a lens surface to achieve the same optical quality. Why Choose a Refractor?
Norman Remer’s book, Making a Refractor Telescope , published by Willmann-Bell, is widely considered the definitive manual for the "ATM" (Amateur Telescope Maker) community. Unlike generic guides, Remer focuses on the specific mechanical and optical challenges of refractors, such as:
A cell that holds the two lenses micro-distances apart (often separated by three tiny foil spacers) without pinching the glass. Once the curves match the target radii using
While Remer’s techniques are fundamentally sound, modern advancements in materials, testing, and coatings allow for significant improvements. Here are 12 modern refinements ("12 new" techniques) often discussed in modern ATM circles:
What (e.g., 4-inch f/15) are you planning to build?
Once ground, the surfaces are transferred to automated or manual pitch laps charged with cerium oxide. Remer's clarity shines in this phase; he explains how to diagnose zone errors, turned-down edges, and surface roughness. He demystifies the act of adjusting the tool shape to bring all four surfaces to a perfect spherical figure. 4. Testing Methodologies and surface roughness.
The most direct interpretation is the desire to build a 12-inch (300mm) refractor. While Remer’s book provides prescriptions up to 8 inches, the fundamental principles and advanced testing techniques he teaches apply directly to making any size. A 12" objective is a monumental, professional-grade instrument. The book provides the optical knowledge needed to even consider such a project.
: Shaping the two elements of the doublet lens to exact spherical specifications.