Thursday, January 27, 2011

Telescopes of Octavian Stanescu


My intention is to collect here some informations about telescopes,amateur telescope making and telescope lore from Romania. 
My aim is to offer a picture about the status of  Amateur Telescope Making  in my country. I dare to add  my two cents here and there because my travel with the Time Machine was a bit longer and I was  whitness and part here of the development of this fascinating hobby.
We start with Octavian Stanescu, nickname Tavi, a veteran amateur astronomer and ATM-er ,living in Timisoara.The city of Timisoara always had an active group of amateurs astronomers and is having a special place as an ATM-ing center.

This picture,made in 1991, is showing from left to right, Tavi ,next is Doru Dragan ,another veteran amateur astronomer who gained the nickname of The Dragon (you will not have an easy life if you start a polemic with him),the son of Doru and Gavril Beches ,an acomplished  mirror maker .About Gavril, (this is the Romanian equivalent of  Gabriel) ,I will come back latter.
The telescope is an alt-azimuthal Newtonian reflector of 280mm aperture F/5 ,miror made by Tavi.The tube was folding down in two parts to fit in the Moskvitch car in the background.

One of the first bigger projects of Tavi was the 380mm  F/4.7 Dobsonian with a Serrurier truss-tube seen at a Star-Party on Semenic Mountain.Octavian is kneeling while colimating the telescope,assisted by Doru Dragan ''the Dragon'' and other two amateurs.
This is a 150mm F/4 RFT Newtonian telescope on a Dobsonian mount with only one side of the rocker-box.Mirrors and mounting by Tavi.He built this telescope specialy for children attending the Star-parties sponsorized by the Astronomy clubs of Timisoara.
Classic Cassegrain reflector,aperture 250mm F=3800mm F/15.2.Mirrors and mounting by Tavi, like for all telescopes seen under this heading.
This is a Nasmyth-Cassegrain telescope of 250mm  aperture F/24, built by Tavi and dedicated for solar observing.This OTA is having actualy two optical sets, for solar observing it is used the uncoated mirror set. Note the elegant stainless-steel tube and the horseshoe mount with clock-drive and slow motions,built to accomodate different optical tube assemblies.

To our knowleadge this is the first Schmidt-Cassegrain made in Romania.Is having an aperture of 120mm,EFL of 600mm, so only F/5,central obstruction is of 40% but the image is aplanatic due to the hyperbolic secondary miror and to the degree of correction (shape) put on the Schmidt corrector.

Next is a short Schmidt-Cassegrain OTA,aperture 250mm F/5.6. Primary miror is open at 2.7.With a three lens corrector,it is intended for an astrograph.

OTA of a Ritchey-Chretien of 300mm aperture,secondary mirror have a diameter of 106mm.The primary miror is having a focus of 850mm ,open at F/ 2.833.
One of the grinding machines of Tavi, rough grinding a 300mm F/4.6 mirror.

The biggest mirror grinded by Tavi is a 500mm miror about which you will find some details below.Please click on the picture to open,to find out about his testing methods and achived accuracy.




Another project finished in February 2011 is a 18 inch F/5.3 mirror.The blank consisted of a huge lens having a diameter of 460mm and a weight of 21 kilograms.

First, a surface of 300mm diameter was diamond generated on the back.After that,the grinding went as usual.


Please see  below the finished mirror of 450mm aperture F/5.3 and of pretty unusual  but favourable shape.


Not bad for a guy who started about twentyfive years ago by grinding on his own a four inch mirror!

Additional information is available on the site of the ''Altair'',one of Timisoara's Astronomy Clubs:
 I did not overloaded this short presentation with technical data,for more details one may contact Tavi at:
''stanescuoctavianatyahoodotcom''
(When typing this adress,please write ''at'' and ''dot'' as read).