Using a pitch lap (a tool covered in optical pitch) and Cerium Oxide, you polish the glass until it is completely transparent. "Figuring" is the ultra-precise process of altering the lens shape by fractions of a wavelength of light to achieve a perfect spherical or aspherical curve. Phase 4: Optical Testing
: Remer covers the design of two-element lenses corrected for color, coma, and spherical aberration. For those who prefer to skip the design phase, the book includes proven "prescriptions" for lenses ranging from 3 to 8 inches in aperture. Grinding & Polishing
Refracting telescopes gather and focus light using a combination of glass lenses rather than mirrors. An unshielded, single-lens telescope suffers from severe chromatic aberration (color fringing) because different wavelengths of light bend at different angles.
This article explores the core principles of Remer's refractor making process and highlights modern, 12-step refinements—or the "12 new" approaches—that can take your home-built refractor from good to exceptional. Why Build a Refractor?
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: It includes specialized Excel spreadsheet programs on a CD-ROM to help builders design lenses corrected for color, coma, and spherical aberration.
The final chapters cover the often-overlooked mechanical aspects of the project:
Because Norman Remer’s book was published by Willmann-Bell (a publisher whose assets were acquired by the American Astronomical Society), finding physical copies can sometimes be difficult and expensive.
The project begins with raw glass discs. Builders must inspect the blanks for internal stresses or bubbles using a simple polariscope. 2. Rough Grinding (Generating the Curve) Using a pitch lap (a tool covered in
Bringing the surfaces to a reflective, smooth finish. 5. Testing (Figuring): Ensuring the curvature is precise. 6. Testing the Pair: Testing the crown and flint together. 7. Designing the Cell: Mounting the lenses.
He leaned into the eyepiece. The planet didn't just appear; it exploded into view. He could see the turbulent swirls of the Great Red Spot and the razor-thin shadows of the Galilean moons cast against the gas giant’s clouds [4, 5]. In that moment, the PDF blueprints transitioned from ink and math into a literal window to the stars [1, 2].
Variant 7 — Dobson-style Refractor (compact)
Following the closure of Willmann-Bell (and its subsequent acquisition by the American Astronomical Society - AAS), physical copies of specialized ATM books can sometimes be difficult to find or expensive on the secondary market. For those who prefer to skip the design
. While amateurs have crafted thousands of reflecting telescopes using mirrors, many have long viewed lens-making as an insurmountable task due to the perceived complexity of grinding multiple surfaces. Remer’s work demystifies this process, proving that making a high-quality doublet lens involves the same fundamental tools and techniques used in mirror-making. Amazon.com Overview of the Book The book spans approximately 391 to 408 pages
Using a strict sequence of coarse-to-fine grits, you systematically grind the curves into the glass elements. Because R2 and R3 face one another inside the cell, they are often ground against each other—frequently called a "testplate" methodology—to guarantee a flawlessly matched interface. 3. Polishing and Figuring
: If you need a basic introduction to refractor mechanics, the American Museum of Natural History provides a simple PDF guide on building a basic refracting telescope using simple materials.