ASTRO-PHYSICS DESIGN PHILOSOPHY APOCHROMATIC LENS DESIGN
These objectives are APOCHROMATIC, which means that the images
are essentially free of false color, both visually and photographically.
Roland Christen selected Super ED to be the heart of his new optical designs
because of its excellent light transmission and superior correction of
all the monochromatic and polychromatic aberrations. Super ED is a
more advanced glass than the more common varieties used in
commercial refractors. It has allowed Astro-Physics to use crown rather than
flint for the outer elements. Normal ED (FK01) and even Fluorite
doublets use flint glasses as the leading element, causing the color
correction to be less than perfect, especially in the violet region of
the spectrum. These flints introduce false color that can be seen as
purple halos around bright objects, or purple fringing along the
Lunar edge and at the edges of bright craters. This color error can
cause brighter stars to bloat on long exposure photographs.
The Starfire EDT design
(which includes the 105 Traveler EDT telescope)
consists of three matched optical glasses to combine the colors of
the visual spectrum into intense, sharp, concentrated images. The
views are extraordinary. As you can see on the specification sheets,
the superb color correction of these EDTs surpasses the fluorite
doublets, particularly in the far violet part of the spectrum where
Technical Pan films have their highest sensitivity.
The highly acclaimed Starfire EDF design has been available over recent years in 105mm, 130mm, 155mm, 180, and world record 206mm diameter. These were
developed with very fast focal ratios for amateurs who long to achieve superb, wide field astrophotographs. For avid astrophotographers, we offer the 155mm Starfire EDF, the new 160mm Starfire EDF and larger EDF refractors with giant 4" focusers to allow coverage of medium format films with minimal vignetting. In the hands of knowledgeable astrophotographers, these instruments can produce superb, professional astrophotographs of all your favorite deep-sky objects. Images are so sharp, it requires enlargements of up to 30" x 40" to resolve the finest details. We also offer the 155mm Starfire EDF with the 2.7" focuser for individuals who desire the ultimate portable, versatile refractor, but do not require the larger focuser.
Their relatively compact arrangement makes the EDF series of telescopes truly one man manageable instruments; affording spectacular views unmatched by any other telescope systems in terms of field of view, detail, color fidelity, contrast and clarity. One of the important advantages of a short focal length is that the mounting can be relatively smaller, lighter and more compact than longer telescopes. The result is a highly portable refractor system with superior imaging qualities, ideal for a wide variety of astronomical work from high-magnification lunar/planetary to deep sky astrophotography.
MOUNTINGS
Astro-Physics equatorial mounts 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. Astro-Physics has also
developed a very accurate worm gear set and state of the art electronics
technology to insure smooth, effortless tracking of celestial objects for
all visual and photographic purposes, and a high degree of durability and
reliability.
To achieve these performance criteria, Astro-Physics 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 engineered in a manner that minimizes
mass and size while maximizing rigidity. For examples of this, study the
tension rods on the piers, and the thrust bearings on the polar and
declination axes that transfer a tremendous amount of load in
relation to their size. To these mechanics is added a drive that is
accurate and sophisticated enough for the most demanding
application, featuring a custom-manufactured fine-pitch worm
gears driven by a high-resolution stepper motor with an advanced hand
held controller. This makes the tracking of celestial objects a snap, even for
beginners.
ACCESSORIES
Astro-Physics telescopes are complemented by the most comprehensive, custom matched series of accessories and options that make these telescopes particularly versatile. From CCD imaging to
35mm and medium format film camera adapters to photo-visual telecompressors, these have carefully designed for functionality
and compatibility. They are all tested and proven in the field under actual observing conditions, and available at most
reasonable prices.
OPTICAL PRODUCTION
Astro-Physics refracror telescopes are designed and manufactured in their modern optical
facility in Illinois, so these telescope lenses are truly 100% AMERICAN-MADE. Using only precision "A" grade optical glass,
which has high light transmission characteristics and is free of striae and imperfection. Each time they begin a new
production run of lenses, Roland Christen computer-optimizes the design based on the particular melt characteristics of the
new glass. Then, Astro-Physics opticians adjust the tooling accordingly to achieve the desired curves.
All lenses are polished on pitch and hand-corrected. Each lens is
tested, polished and tested repeatedly throughout the production
process. This continues until the desired performance is achieved.
During the final figuring stage, the lens is evaluated with a laser
interferometer. Mass-production techniques are not employed as it is
impractical; each lens is treated individually. This process is very
time-consuming, but there is virtually no other way to attain the level of resolution, definition, and contrast that the most
demanding applications demand.
The combination of the apochromatic lens design, careful, precise
optical production techniques, high-transmission multi-coatings and
well-baffled tube assemblies results in a clean optical system with
superior contrast and light grasp.
MACHINING CAPABILITIES
Most of the mechanical components are machined in-house on
ultra-modern three-axis CNC (computerized numerical control) lathe
and CNC machining center. Highly skilled machinists maintain
very accurate tolerances thereby producing components that uphold the
Astro-Physics reputation for rigid mountings, precision tracking, smooth
operating focusers, and unrivaled accessories.
TUBE ASSEMBLY
The Optical Tube Assembly Department at Astro-Physics carefully installs the
baffles within the telescope tubes to insure that the placement is precise thereby effectively eliminating stray light. The
interior of the tube is then finished
with an anti-reflection black paint. Each lens cell and focuser are
squared onto the tube in preparation for the final assembly and
final collimation (alignment) of the telescope.
MOUNT ASSEMBLY
The Mount Assembly Department is staffed by professional
telescope makers who are advanced users and observers. Their experience
is brought to bear during the design, fabrication, and final assembly of
each mounting. During assembly, the staff works diligently to assure the
mount adjustments (many done by "feel") are nominal. And here is where the
hand controller and motor components are carefully assembled, with components being soldered to the circuit boards, and all
components tested prior to shipment.
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