A new generation  Harmer Wynne Astrograph

The TI 45  is a new generation astrograph born after  in-depth and extensive studies lasted three years.

It combines a number of innovative features and special solutions.

The design was carried out by a professional team driven by an aerospace engineer (all amateur astronomers from a life). Mechanical design was performed in a 3D environment and FEM analysis have driven the sizing of the components. 

From optical, mechanical, electronic and design point of view, the TI45 Astrograph is the most advanced telescope which you can find on the world market.

The TI 45 astrograph, in the fast f/4 configuration, is derived from the configuration Harmer-Wynne (designed for the first time and published in 1976 – Royal Astronomical Society, Monthly Notices, vol. 177, Oct. 1976, p. 25P-30P). The Harmer-Wynne instruments have the particularity of combining a parabolic primary mirror with a spherical secondary mirror and obtain a corrected wide field with the aid of a two elements corrector.

In our TI 45 Astrographs, it is introduced a further refractive element correction (in ED glass) – this 3th lens introduction was done by Leonardo Priami in late 2010 as described in its web site LINK-, reaching a real diffraction limited corrected field of over 80 mm in diameter without introduce color aberrations (from 400 nm to 1,6 micron of wavelength). These performances of very fast and very corrected optics allows to this optics to be used with success both in narrow band filter imaging and in Near Infrared imaging.

For the most deep sky imaging, the TI 45 astrograph, in the “all-around” f/8 configuration, is a Corrected Cassegrain with an hyperbolic secondary mirror and two elements corrector. It delivers an awesome performances and real diffraction limited from 380 nm up to 3 micron wavelenght (and over), for more than 70 mm of field. The real obstruction is limited at 38,7% with a useful 83,8% of incoming light.

 

The TI 45 Astrograph is not a simple telescope, but it is really two telescopes in one.

The TWO configurations (the fast f/4 and the “all-around” f/8) are “native” and both optimized. No “Barlow” lenses are used neither “focal reducer”.  You can shift from one to the other in less than five minutes without loss of collimation thanks to the special secondaries holder and thanks to the spherical secondary mirror of the f/4 setup. You can leave in place all your instruments (CCD camera, filter wheel, focuser, AO, OAG, ecc), after a configuration change, you only have to refocus a little!

THE MOST IMPORTANT FEATURES:

  • Effective optical aperture: 450 mm
  • Native dual focal length (1800 mm f/4, 3600 mm f/8) interchangeable within five minutes
  • Awesome optical performances for both configurations (see OPTICAL PERFORMANCES)
  • Extreme stiffnes and thermal stability (thanks to extensive use of carbon)
  • Extreme lightness  (thanks to extensive use of carbon)
  • Easy collimation
  • Compact dimensions
  • Built in 4″ electronic field rotator (ASCOM compatible)
  • Built in electronic control boards and proprietary software
  • Extreme modern italian design

 

   
TI 45 Astrograph - Dual Focal Length
Technical dataf/4f/8
Focal length (mm)18003600
Optical ConfigurationModified Harmer-WynneCorrected Cassegrain
Parabolic Primary Mirror
Diameter (mm)456
Thickness (mm)50
Effective optical aperture (mm)450
f/f/3
MaterialSchott Suprax*
CoatingAlum. Enanced >94%
Secondary Mirror
Diameter (mm)238166
Thickness (mm)2420
ShapeSphericHyperbolic
MaterialSchott Suprax*
CoatingAlum. Enanced >94%
Corrector
Type3-Lenses ED2-Lenses
Corrector lens diameter (mm)12694
CoatingMulty layers 400-900 nm
Real Diffraction Limited field diameter (mm) (considering Polychromatic 400/700 nm)8372
Effective Obstruction (of the secondary baffle) (%)54,6%38,7%
Light incoming (% of aperture area)70,0%83,8%
Back Focus from primary vertex (mm)347346
Loss of light (vignetting) @ 26 mm from axis (%)5,0%5,0%
Loss of light (vignetting) @ 30 mm from axis (%)11,0%7,0%
Spot Diagram RMS Diameter @ 26 mm from axis - Poly 400-700 nm (micron)2,24,52
Spot Diagram RMS Diameter @ 30 mm from axis - Poly 400-700 nm (micron)2,586,64
* Ceramic Mirrors on request