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3,5" Prime Focus Field Flattener for Astro-Physics 130 StarFire GTX
Optical accessories for the 130GTX
A special Field Flattener and a Focal Reducer/Correktor have been developed for the large 3.5" focuser of the Grand Tourismo 130 GTX. Both optical elements can be used once the 2.7" focuser of an older 130 EDF-GT has been replaced with the 3.5" focuser.
The Field Flattener extends the focal length a little bit, the resulting f/ratio is f/6.7. It provides a field of view with 65 mm diameter without vignetting and delivers a diffraction limited image even at the edge of the image circle. This is equal to a field of view with a diameter of 4.3 degree at the slightly larger focal length of 870 mm.
This way, it sets a standard for our time. It works perfectly, even with the large CCD-sensors which are currently used by amateur astrophotographers (like e.g. the Kodak KAF 50100 with a size of 49.1 x 36.8 mm and a diagonal of 61 mm at 8.208 x 6.132 Pixel and 6 mü).
Test image of the Propeller Nebula (DWB-111 and DWB-119), imaged with SBIG STL-1100 using Field FlattenerThe following table shows the field of view of the 130 Starfire GTX combined with the Field Flatteners and several CCD-sensors.
Size [mm] Field of view [degree] Fully Illuminated Circle 2.6" (65 mm) 4.3° (256 min.) KAF-8300 18.0 x 13.5 mm 1.2° x .88° (71 x 53 min.) APS-C 22.3 x 14.9 mm 1.5 ° x .98° (88 x 59 min.) 35 mm Full Frame CCD 24 x 36 mm 2.4° x 1.6° (142 x 97 min.) KAF 16 803 36.8 x 36.8 mm 2.4° x 2.4° (146 x 146 min.) 
As with all optical systems which change the focal length, the distances between lenses and camera sensor have to be kept as exact as possible. This is why there are several camera adaptions available for this flattener. Please visit for detailed information the original website of Astro-Physics.
There is a special backspacer ring available for this Field Flattener. Its optical length is exactly 22.1 Millimeter. The necessary distance from the back of this backspacer to the image plane is 80.8 +/- 2.5 Millimeter. To attach your camera, you need one of the following five adapters. If you require more backfocus, you can leave out the backspacer - then, the required backfocus is 102.9 +/- 2.5 Millimeter.
Flattener and backspacer do end in a 3.3 inch male thread. The backspacer is included with the Reducer/Correktors.
Article number Camera Adapter 140 8478 (ADATCCEOS) Canon EOS 140 8479 (ADATCC1) SBIG STL with Five-Position Filter Wheel Adapter 140 8480 (ASACCT2/ADASCTLM ) SBIG STL with Eight-Position Filter Wheel Adapter 140 8480 (ASACCT2/ADASCTLM ) 2"Nosepiece Adapter 140 8423 (A 3513) QSI 500/600 Cameras 2408145 + 2458215 Zeiss M68 Adapter pdf-file: Schematic showing Backfocus Spacer and Adapter spacing.
If you have any questions about attaching your accessories, please give us a call or send us an email. For further information and useful accessories about the 130mm f 6,3 StarFire GTX Triplet Apochromat Refractor please visit the Website of Astro-Physics.
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Additional Information
| Manufacturer | Astro Physics |
|---|---|
| SKU (#) | 1405351 |
| EAN Code | 4047825035868 |
| Net weight (kg) | 0.93 |
FAQ
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Eyepiece Projection - How good can it get?
HIGH-QUALITY PROFESSIONAL ASTRONOMICAL MOUNTS
Astro-Physics 130mm/ f/6.3 StarFire GTX Refractor "Gran Turismo"
Keeping to the same quality standards that have made the fully-apochromatic refractors legendary, Roland Christen's company has been building German Equatorial GoTo mounts for more than three decades. Their proven stability, accuracy and durability is the reward for anyone who can endure the traditionally long delivery times.
"El Capitano" at Dome C of the Concordia Station in Antarctica"
Two "el Capitan" mounts are working in the Antarctic for several years now, even at temperatures of -75°C. They are perhaps the most spectacular example of the durability of the sturdy Astro-Physics mounts and are representative for many more exemplars that often run for decades at our customers without failures.
Astro-Physics GTO 1600
With a very accurate manufactured worm gear the Astro-Physics mounts are equally well-suited for smooth, effortless tracking of celestial objects as well as for all visual and photographic purposes.
Astro-Physics supplies 4 mounts with 30kg to 135kg instrument load. The GTO 1100 and GTO 1600 series are especially remarkable, because they are fully transportable - despite their high instrument load. This is possible because the declination axis can be separated from the rest of the mount. Even the GTO 1600, with 90 kg instrument load, can be transported and set up by one person!
The separation of RA and DE axis and on the right: The CNC machined dovetail of the RA axis to accommodate the DE axis
The connection of the two components is achieved by a CNC-machined dovetail receptor clamp which has the same uncompromising stability. This is also used by "normal" dovetails.
In the case of the GTO3600, the declination axis can also be separated, but this mount is transportable only to a limited extent and better used as a stationary mount.
At the moment, the GTOMACH2 Universal Robotic Mount is the only mount of German design in its weight class, in which ALL cable connections to the telescope (CCD camera, electric focusing, etc.) are passed through the polar axis. The Mach 2 GTO replaces the long proven Mach 1 GTO of Astro-Physics. Universal Robotic means that Mach2 fulfills all of the requirements of a robotic mount for automated operation for imaging, satellite tracking, comet tracking, star survey work and others.
State-of-the-art CNC machine technology and hydraulic circular grinding machines
All parts of Astro-Physics mounts have been CNC-machined and milled out of solid aluminum. In this way, it is possible to circumvent the expensive, labor-intensive production of blanks made of aluminum sand casting.
By using state-of-the-art CNC machining techniques, where surface and angular(!) accuracies of 1 micron allow highly accurate fits, all "blind" volumes of axis and housing parts that do not contribute to the rigidity of the design are erased from the solid aluminum.
Due to the ingenious combination of two tapered roller bearings and three thrust bearings in each of the two housing parts, the axles themselves are even more relieved and stabilized by the shape of the axle housing. This results in a mount of high rigidity and freedom from vibration with a surprisingly low weight.
Features of GTO Servo Drive (applies to all 4 models)
Why does Astro-Physics choose servomotors instead of stepper motors to drive their mounts?
The torque and thus the acceleration of stepper motors reaches their maximum value at low frequencies and drops sharply at high frequencies. Therefore, relatively large motors are necessary to develop enough torque for positioning at the required speeds. At low speeds, so like during normal tracking, such engines have far too much force and then often run uneasily, which can easily lead to vibrations of the telescope.
In addition, stepper motors have natural resonances. In these frequency ranges, the smoothness deteriorates again rapidly. Servo motors, on the other hand, are characterized by high torque even at high speeds, very good running smoothness over the whole speed range and higher efficiency. In order to obtain the same positioning accuracy as with stepper motors, however, a higher electronic effort must be driven.
All functions of the servo drive can be controlled from a laptop or PC. Astro-Physics has a fully supported, working ASCOM V2 driver for all Astro-Physics GTO mounts. This is the recommended method for controlling the mount with a personal computer under the Windows operating system. Please refer to this link http://www.astro-physics.com/index.htm?products/accessories/software/ascom/ascom für weitere Informationen und Links zu der ASCOM-Plattform und dem Astro-Physics V2 ASCOM-Treiber.
GTOCP4 Controll Box for Servo Drive (for GTO-1100, GTO-1600, GTO-3600, GTO Mach1)
All GTO mounts produced since 1998 can easily be upgraded.
For the new GTO-Mach2 Universial Robotic Mount Astro-Physics has developed a new control system (GTOCP5) which combines the precision performance of the Renishaw Resolute Absolute Encoder with the whisper-quiet motion of brushless micro-step servo motors to produce a very accurate observatory-grade mount that can also be set up in just a few minutes in the field. The mount can be operated manually via the clutches or electronically with the encoder loop providing the pointing and tracking functions.
Some Features of the GTOCP4:
- completely redesigned with modern chip technology, resulting in faster processing speed and increased memory capacity for future feature additions
- GTOCP4 supports floating point operands to improve calculation accuracy and coordinate conversions
- includes features from the latest version of the GTOCP3
- Backward Compatibility: All of this is in a compact size that fits all previous GTO mounts (400 GTO, 600 E, Mach 1, 900/1100/1200/1600 and und 3600 GTO)
Further information and technical details about the GTO Control Box are available here.
GTo in Perfection via Handcontroller (optional)
ALL Astro-Physics mounts with servo motors are controlled via the GTO control system and can be operated completely via the keypad. The interface between the hand control and the mount is the GTO control box. It is mounted directly on the pole block, except at the MACH1. There, the GTO control box is attached at the tripod.
The Keypad can be used with all versions of the Astro-Physics GTO Control Boxes: GTOCP1, GTOCP2, GTOCP3 and GTOCP4.
The Keypad is intuitive and easy to use and is equipped with great features to make the observing session productive and pleasurable. Entering long, hard-to-remember keyboard sequences has been deliberately avoided.
This "handheld computer", which even cold winter nights can not harm, is the usual hand control box for controlling the mount equipped with a variety of options:
- programming of the periodic worm error and the gear play in right ascension and declination are possible, of course
- fully automatic positioning of the mount on the object you have entered
- a choice of different correction and pointing speeds are available
- contains more than 17,000 objects in extensive databases
- mehrere eingebaute Software Routinen erlauben eine schnelle und einfache Justierung der Polachse
- several built-in software routines allow quick and easy polar alignment
The control software can be updated via internet. A PC or laptop is not needed. If required, all mounts can also be controlled via the following external software packages:
- PulseGuide
- TheSky
- GUIDE
- Desktop Universe Earth Centered Universe (ECU)
- SkyMap Pro
- Starry Night Pro
- any software that is ASCOM compliant. .
Further information and technical details about the GTO Keypad is available here.
Further information and technical details about the Astro-Physics German Equatorial Mounts is available here:
Astro-Physics GTO-1100 (various versions available)
Astro-Physics GTO-1600 (various versions available)
Astro-Physics Mach2GTO Mount (#1401372 , € 16525)
Astro-Physics GTO-3600 (various versions available)
Delivered over a period of almost 15 years, the GTO 1200 is no longer available and will be replaced by the GTO 1600. The Mach 2 GTO replaces the long proven Mach 1 GTO of Astro-Physics.
Accessories for the GTO mounts from Astro-PhysicsOf course, there are many mechanical accessories for the mounts - from the instrument mounting plate to dovetail clamps to the transportable pier. - For details, see our Astro-Physics price list or visit the Astro Physics website (www.astro-physics.com).
