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A Ritchey Chretien 14 " telescope construction

This kind of telescope was created for several reasons: one was the technical need to have a large paved area in order to fully exploit the currently used CCD (Sbig 11k); also the economic factor, that the purchase of such a tool entails, has led me to this solution; but the decisive factor was to create a custom telescope having the necessary characteristics to be used with ccd. After using for some years an SCT 12 ", I decided to take the step. For optics i chose Ariete telescopi and after waiting about 8 months I have received mirrors at home. These are the characteristics:

Then on December 8, 2007 I started work. I designed the production of a carbon truss system. Below are some phases of the development of the "cradle"


Below is shown the realization of the rocker arms (pic. 1 and revised) that are part of primary mirror holder.




Below: In pic 2 is visible the inside breech. While in pic. 3 the outside breech with the collimation screws which act on the brass bushings. In pic.4 is shown the inside breech, complete with the primary mirror holder.


pic 2
pic 3
pic 4


Below: Some details of the rocker arms (pic 5) and the first position of the mirror (pic 6)


pic 5
pic 6


Further processing of the focuser support and field flattener, while in pic 6 and 7 are shown some secondary mirror holder elements.




Realization of secondary mirror holder, pic 9 some ultimate elements




Below secondary mirror holder and spider (pic 10). While pic 11 and 12 you can see the full system. Note that the cradle that supports the primary mirror holder was made of iron, while the connection between the cradle and the ring that supports the spider are in homemade carbon truss.


pic 11


Below you can see some details of the structure, pic13 shows all the elements after after the process of anodization.


pic 13


Here are the pictures of the telescope, but still without mirrors. In the rear view (pic 14) are visible the fans and the cable:

Telescope is provided with an anti-condensation system located on the frame of the secondary mirror and with

temperature and humidity sensors placed behind the two mirrors and over ring that support spider


pic 14


These are the telescope and camera system data:

Telescope: Ritchey Chretien optical design

Aperture: 350mm

Focal ratio: f/8

Focal Lenght: 2800mm

CCD: Sbig STL11k

Pixels size: 9x9micron

Array size(pixel): 4008x2672 in bin 1x1

Chip size: 24mm x 36mm

Image scale: 0,66 arcsec x pixel

Fiel of view: 29,5 x 44,2 arcmin

Field flattener: Realizzato da Massimo Riccardi

Weight: 35kg (scope + imaging train)


Here are some tests done on one of the first images.




The test was carried out under non optimal weather conditions (these conditions were empirically estimated with reference to better conditions already occurring from the same observing site). Transparency was not optimal with high humidity (measured at about 80%). The tests were performed on frame of 15min each one, taken using adaptive optics at the speed of 7Hertz, with a 8.6mag guide star.

In this single frame the measured curvature value is 8.6%, and now appears to be the best reading value. While 11% is the average curvature value taken over several frames.