Astro-Physics, Inc

Double Rainbow Over Astro-Physics

ASTRO-PHYSICS has been developing telescopes and accessories for the advanced amateur since 1975. We now offer an extensive line of precision telescopes and mountings, all with outstanding performance for a variety of observing needs. If you have decided that refractors fit your requirements, you will find our line of Apochromats to have the highest performance of any refractor on the market. Our telescopes were developed with the active observer in mind. We have concentrated on those things that make observing a joy: sharp high-resolution optics, rugged vibration-free mountings and easy-to-use, effective accessories.

Historical Perspective

Astro-Physics has been at the forefront of optical design for more than a decade. In the early 1980s, Mr. Roland Christen, founder and president of Astro-Physics, introduced the first high performance affordable apochromats to the amateur market. These early Astro-Physics refractors were quite revolutionary and were a major influence in the rebirth of refractors.

The more common achromats available at that time showed significant chromatic aberration even with focal lengths of f15. They were (and still are) very long and awkward, particularly if portability to a dark sky site is desired. Both 5"f15 or 6"f15 doublet tube assemblies (focal lengths of 75 and 90 inches respectively) require a substantial mount on a tall pier or tripod to accommodate the length of the instrument and counteract the torque reaction that is inevitable when the breezes blow. The chromatic aberration coupled with the enormous size and weight of these instruments and their mountings deterred many amateurs from using refractors larger than 4" in the 1960s and 70s.

As an avid amateur astronomer, Roland was dissatisfied with the telescopes that were available in the 1970s. He knew that even the achromats of the day showed snappier images than his 8"SCT, but he wanted a shorter scope which could be used for photography as well as high-definition planetary images. Over a period of several years, he designed and built several refractors with shorter focal lengths using a triplet design. The color correction was very good even as short as f6.

In the 1980s and 90s, Astro-Physics' optical designs evolved several times and with each new design, new levels of performance were achieved. The quality of construction of the tube assemblies, sophistication of the mounts and range of accessories have also improved each year.

In 1992, we were very proud to introduce our line of refractor lenses which incorporated synthetic fluorite ED glass in various optical designs. This optical material has further revolutionized the modern refractor by all but eliminating the last vestiges of false color in fast refractors.

Since the early 90s, we have expanded our production facilities with the most modern CNC production equipment available. This includes computer automated lathes and machining center complete with a CAD-CAM design center. We have also installed one of the most advanced optical production systems in the world. The Opticam SX, a computer automated precision-lens generator, was originally developed to produce high-end military and space optics. In 1999, we added the OptiPro PX250, a high-tech computer optical polisher.

Astro-Physics Design Philosophy

At Astro-Physics, we are fully committed to the production and development of amateur telescopes and accessories. Our goal is to produce the highest possible quality components and keep them affordable to the average amateur. Amateur telescopes are the only product that we produce; we do not get sidetracked into commercial or military projects. Many of our technical and production staff are amateur astronomers themselves, so they understand the unique needs of our customers. We strive to build almost every part from scratch at our own facility in Rockford, Illinois. This includes not only the individual optics, but also the critical gears, circuit boards and components right down to the knobs and fittings.

Apochromatic Lens Design

Our objectives are APOCHROMATIC, which means that the images are essentially free of false color, both visually and photographically. We have chosen the most advanced synthetic fluorite E.D. glass to be the heart of our optical designs because of its excellent light transmission and superior correction of all the monochromatic and polychromatic aberrations. There are many less expensive E.D. (Extra low Dispersion) glasses on the market which can be used to make refractor lenses. The most commonly used E.D. materials only partially correct the secondary spectrum errors, while the least expensive versions are little better than traditional crowns used in old-fashioned doublets. Lenses made from these materials can provide satisfactory views for some individuals, but those amateurs who demand that last bit of contrast and definition will find there is no satisfaction in using a lens made from less expensive materials.

The StarFire EDF design was originally developed for our 6" astrograph. We found it to perform superbly as a visual planetary instrument and therefore converted all of our lenses to that design, including the 105 Traveler. The views are extraordinary. The superb color correction of these EDFs surpasses the fluorite doublets, particularly in the far violet part of the spectrum where Technical Pan films have their highest sensitivity. Our latest designs have excellent infrared corrections to 10,000 Angstroms, making them very suitable for CCD imaging. Color curves are available for each current lens design.

The fast focal ratio of the StarFire EDF design is particularly attractive to amateurs who long to achieve superb, wide field astrophotos. For avid astrophotographers, we offer these EDF refractors with giant 4" focusers to allow coverage of very large film formats with minimal vignetting. In the hands of knowledgeable astrophotographers, these instruments can produce superb, professional astrophotos of all their favorite deep-sky objects. Images are so sharp, it takes 30" x 40" enlargements to resolve the finest details.

We also offer several models with the EDFS designation that incorporate the 2.7" focuser. These refractors are for those amateurs who desire the ultimate portable, versatile refractor, but who do not require the larger focuser.

One of the important advantages of a short focal length is that the mounting can be smaller, lighter and more compact. The result is a highly portable refractor system with superior imaging qualities, ideal for a wide variety of astronomical work from high-power lunar/planetary to deep-sky astrophotography.


Astro-Physics mountings are designed for solid stability under a variety of observing conditions. At the same time, the mounts are truly portable so that amateurs can transport them to their favorite dark-sky site and set them up quickly and accurately. The mountings break down into manageable sizes, but when set up, they are extremely rugged and steady platforms. We have also developed a very accurate worm gear set to insure smooth, effortless tracking of celestial objects for all visual and photographic purposes.

To achieve these performance criteria, we combined the latest technology with time-tested design concepts. The basic mounting configuration was engineered with proper vibration and strength of materials criteria. As in a good building design, all loads are channeled into massive load-bearing cross sections to their final destination - the ground. This is done in a way that minimizes weight and size while maximizing rigidity. To this stability, we have added a go-to servo drive that is accurate and sophisticated enough for the most demanding application. We started with a custom-manufactured fine-pitch worm gear and added a high-resolution DC servo motor drive with a hand-held computer go-to keypad controller. The drive system allows slewing up to 5 degrees per second, yet smooth guiding motions as well.


To these basic telescope components, we have added a whole list of accessories that make our telescopes versatile. From camera adapters to telecompressors, we have carefully designed them for their functionality and compatibility. They are all tested and proven in the field under actual observing conditions.

Astro-Physics Facility and Staff

In September 1990, our dream of moving into a new, specially designed facility came true. Since Astro-Physics is one of the few telescope companies that actually make most of the items in their product line, we needed a building that would allow us to perform each function in the most efficient manner. Over the years, we have assembled a staff of talented, skilled craftspeople dedicated to producing very high quality products. They take personal pride in their accomplishments and in your satisfaction.

Optical Production

Photos of our optical production facility

We manufacture all of our telescopes in our modern optical facility, so our telescope optics are 100% AMERICAN-MADE. We use only precision "A" grade optical glass, which has high light transmission characteristics and is free of striae and imperfection.

All optical surfaces are finish-polished on pitch and hand-corrected. Each lens is tested, polished and retested repeatedly throughout the production process. We continue until the desired performance is achieved.

In 1995, we installed a new Opticam SX computerized microgrind system to our optical department. Originally developed at the University of Rochester Optics Laboratory for advancing optical technology in America, the Opticam system completely eliminates all traditional tooling and fixturing needed for fabricating precision optics. A raw glass blank is loaded into the machine, and a finished, ready to polish lens element results in only 25 minutes. All this is accomplished without grinding components or grit. The glass surfaces are rough and fine-ground, edged and optically centered with a series of special bound diamond tools. Tool motions are computer controlled with 100 nanometer resolution. Almost any spherical surface can be generated, convex or concave, as well as the most complicated aspheric that can be described by a mathematical expression. This is all done in a clean, temperature-controlled environment that ensures the highest possible accuracy and precision in the final product.

In 1999, the first Optipro PX250 polisher was installed in our facility. This advanced computer polisher is the only machine of its kind. Older high-speed polishers relied on careful cutting of a polishing pad to achieve even action over the optical surface. The PX250 gently oscillates the tool across the surface so that in a typical 20-30 minute cycle, every part of the polisher spends time on every part of the glass surface. This produces and maintains a very accurate spherical surface on the part being polished.

Common high-speed processes run up to 5000 RPM and can distort the glass because of the heat generated. While capable of blasting out parts in just 5-6 minutes, they tend to leave a rough, zony surface that lowers contrast in the final image. Our computer polisher runs at a mere 200 RPM, and consistently produces 1/10 wave surfaces from start to finish. Since it runs automatically, it leaves the optician much more time to do other more critical tasks.

Where the opticians used to spend an inordinate amount of time in the dirty, time-consuming jobs of grinding and polishing, they can now concentrate much more time on figuring the optical surfaces which is still done on pitch. The Opticam SX and PX250 are examples of the total commitment we have at Astro-Physics to the hobby of amateur astronomy.

As part of our overall Quality Program, Astro-Physics installed a Fitzeau interferometer that allows us to measure the wavefront error of a lens during the final figuring phases. The lens is held in a special multi-point flotation cell in a vertical orientation to simulate actual observing conditions. The interferometer uses two wavelengths of light, yellow and green, to fully characterize lens aberrations. The interferometer is used as part of the lens making process, not just as a final quality assurance check. Lenses are finished one at a time until they meet or exceed our quality standards. A lens is finished when it displays a wavefront accuracy of l/50 RMS (Strehl Ratio of 98.4%). This is well within the diffraction limit, and a lens with this smooth of a wavefront will be a superb planetary objective.

Design Engineering

We are fortunate to have a full staff of engineering talent with decades of experience in mechanical, electronic and software design. What begins as drawings and calculations on the computer screen eventually ends up in the hands of our top-grade machinist as a finely-crafted work of art. Our CAD-CAM system is so sophisticated that every surface of a part is fine-machined and de-burred automatically. Even parts that are buried deep inside an assembly and may never be seen by anyone are fully machined, de-burred and finished to a high degree with no rough edges or saw marks to mar the integrity of the final product.

Our in-house electronic assembly uses ruggedized components and techniques common to aerospace manufacturing. In fact, our electronic design engineers both have many years of aerospace design background.

Machining Capabilities

Most of our components are machined in-house on our ultra-modern 3-axis CNC (computerized numerical control) lathes and CNC machining center. Our highly skilled machinists maintain very accurate tolerances so that parts fit together precisely with no slop. As a result, our mountings are very rigid and our focusers are smooth with no wobble.

Tube Assembly

Tube assemblies are now fully machined, complete with machined-in baffles, on our CNC lathe. This insures that all mechanical components from the focuser to the lens cell are accurately held in perfect optical alignment. The tubes are finished with a high quality polyurethane paint on the outside, and a flat-black finish on the inside.

Mount Assembly

Our mount assembly department is staffed by highly experienced professional telescope makers who are also advanced users and observers. Consequently, they understand how a precision mounting should feel and be adjusted. This experience is brought to the construction of each mounting. The components of our hand controllers are carefully soldered to the circuit boards and tested prior to shipment. Circuit boards and electronic components are purchased to the more rugged industrial specs instead of the cheaper consumer specs so common in inferior equipment. The components of our telescope drives will perform properly from the coldest Arctic to the hottest desert conditions that an amateur is likely to experience.

Packing and Shipping

When you receive your order, you will discover that a great deal of care was given to the safe packing of each item. It is very rare that any item is damaged during shipment.

Office Personnel

The office staff will be your primary source of information regarding products and prices, estimated delivery dates and the status of your order. If we can be of assistance to you in any way, please ask.

Copyright © 1999-2006, Astro-Physics, Inc. - All Rights Reserved
This page was last modified: February 7, 2006

Astro-Physics, Inc.
11250 Forest Hills Road, Machesney Park, IL  61115, U.S.A.
Phone: 815-282-1513   Fax: 815-282-9847