telescops 50cm RC Telescope
C14 Telescope
4" Fluorite APO Refractor
Other Telescopes
Cameras Meteor Camera
Cooling Camera
1. CCD Camera
2. CCD Camera
3. CCD Camera
Mintron and Watec
Other Instruments Collimating Laser
Sun Protuberance Viewer
Weather SAT Receiver

A short description of technical features


20" RC telescope
image 59KB: 50cm RC-telescopeSpecification of Optics
  • optical system: Ritchey Chretien
  • effektive focal length: 4m
  • focal ratio: f/8
  • optical diameter of primary mirror: 50cm = 20"
  • system accuracy (peak to valley at focus): λ /10 wave front
  • manufactor of mirror: LOMO St. Petersburg (Russia)

  • Mechanical Specifications
  • open Half-Serrurier-Tube, Serrurier-aquivalent at Main-Mirror side
  • Grubb Mirrorsupport with temperature-compensated lateral elements, consequently suitable for RC
  • extremly stable Spiderring and secondary Mirrorsupport, consequently suitable for RC
  • Fork-Mount with special designed bearings and friction wheel drive in secondary stage
  • optimal allotment of weight, therefore less vibrations
  • focal instrument loading up to 15kg without change of telescope modelling in the software
  • all mechanical perpenticular errors adjustable, unique for Telescope-Mounts
  • primary gears: nearly zero mechanical backslash in both axes, nearly zero periodical error
  • wet mirror cleaning without dismantling the telescope, new collimation not required
  • material: welded stainless steel, intentional no carbon
  • producer: whole telescope is self-made at harpoint-observatory in 1996-2000
  • technical designer: Ing. Rudolf Pressberger (Austria) 1995, 1996
  • well-documented: construction plan available for do-it-yourself projects only (copyrights by R. Pressberger), details here (in german)

  • Electrical Specifications
  • direct current servo drive, PC controlled by Dr. Manfred Stoll
  • complete telescope modelling in the software used for positioning and tracking, therefore better then tpoint or maxpoint
  • precision of positioning: 25 arcseconds typical at whole sky
  • precision of tracking: 5 arcseconds per hour at Vertikal. Even better at Meridian (without Autoguider or PEC)
  • secondary mirror motorfocuser without any shift, computer controlled temperature-compensation of focus
  • temperature measurement of main mirror with fan control
  • source-code available if telescope is developed as a do-it-yourself project (copyright Dr. Stoll)
  • Description:

    Dimensions of primary mirror: weight= 40kg, mechanical diameter=52cm, thickness=8cm, mirror-hole diameter=15cm, material=Astrositall. Dimensions of secondary mirror: diameter=19cm, thickness=3cm. Mirror spacing between primary and secondary-mirror = 100.3cm. Back focus behind primary mirror surface = 32cm. Field of view diameter without vignetting = 8cm.

    Design of the mechanics: APTM the "Austrian Precision Telescope Mount" by Ing. Rudolf Pressberger in its latest version 1995, 1996. A professional steel fork-mount construction. The first version of APTM was developed until 1978 by Mr. Pressberger. He was worldwide the first amateur astronomer who built his own 1m-RC telescope singlehanded. He developed his own methods for grinding and testing the optical mirror surfaces too. Have a look for his superlative observatory named "Purgathofer Sternwarte" here (see also the german Wikipedia). The design was published in 1986 in the austrian journal "Sternbote". Rudolf Pressberger died in the year 2001.

    In the latest version of APTM (1995, 1996) we have friction wheel drive with selfmade special bearings in both axes, only designed for aequatorial teleskope mounts. The whole telescope is easy to built if you are able to weld sheet metal. Up to 10 observatory-telescopes was buildt in Austria, using the design of Pressberger. Today (2010) further one are under construction.

    The yearly maintenance of the telescope is very easy: Washing the mirrors, adjusting the gears (summer/winter adjustment) and wipe off the friction wheels with special oil.

    Conclusion: "you can't find a better design for do-it-yourself observatory-telescopes"

    The computer controlled drive was developed by Dr. Manfred Stoll under DOS. It allows modelling all the 6 static mounting errors and one flexure term (similar tpoint) since 1978 (in it's first version for the professional 1.5m Zeiss-RC at Leopold Figl observatory / university of vienna) still before tpoint was available. Mr. Stoll has updated his software (9 versions) till 2000. The 1m-RC of Purgathofer observatory works with version 9. With our own new version 10 (client/server-architecture) we are able to guide the ISS and other satellites. Exchange of data with Guide8 and similar software now. The client is a selfmade Windows-GUI with the capability of a supervisory and control system of the whole observatory, including remote operation. It works intentional without ascom.

    image 98KB: C14Specification of Optics
  • optical system: Schmidt Cassegrain
  • effektive focal lenght: 3.91m
  • focal ratio: f/11
  • optical diameter of primary mirror: 35cm
  • manufacturer: Celestron 1987
    Mechanical Specification
  • German-type mount of steel, axes diameter 85mm and 70mm
  • manufacturer: SIDERES, Duisburg (Germany), 1988
  • stepper-motor worm-gear drive with friction clutch
  • Description:

    The mirror shifting of the main mirror is a well-known problem.

    The German-type mount allows using of different optical tubes and so it is a completion of our main instrument. Note also our roll-roof observatory.

    4" Fluorite APO Refractor
    image 27kB: Genesis refracting telescopeSpecifications
  • optical system: four optical elements in two groups
  • focal lenght: 0.5m
  • focal ratio: f/5
  • manufacturer and type: Tele-Vue GENESIS 1992

  • Description:

    Used for wide-field views with Nagler-type eyepieces. It is mounted as "super-viewfinder" at C14-tube.

    Other Astronomical Instruments
    image 29kB:compare our tubes RC50-C8classical C8 in orange-outfit (20cm SC-telescope, 1983) for transportable use only, adapted with 4-steps mechanical focus-counter. Look the image nearby for size comparison to our main instrument.
    image 39kB: travel mount
  • A little traveler-mount (VIXEN) for reflex-cameras, stepper-motor drive.
  • Celestron Comet Catcher: Schmidt Newton optics, optical diameter 14cm, focal lenght 50cm
  • Russian Maksutov MTO-1000 "Russentonne": focal lenght=1m, optical diameter 10cm, mirror support adapted
  • some binoculars
  • image 35KB: little solar telescope
  • handheld solar-observatory by Prof. SOLC:
    A little 1 inch parabolic mirror with focal lenght of 3m is used as "Schiefspiegler". Projection of the Sun at a piece of paper.

  • Cameras

    Meteor camera
    image 28kB: Meteor camera with fish-eye lens image 47kB: viewing of meteors with tele-lens and wireless videotransmission
  • 3-stage Image-Indesifier-tube, generation one, 25cm long, S1-Photocathode 18mm
  • selfmade Shutterblade
  • SW-Videocamera adapted with Relaisoptic (fl=10mm, f/1.0)

  • Description:

    The intensifier-videocamera can be used with NIKON fish-eye optics fl=8mm or fl=16mm. We get a field of view about 180 degree at aperture f/2.8. In 1993 we recorded perseid-meteors up to mag. 3.5. Today the sensitivity of the tube decrease because of age-worn.

    image 12kB: cooling-camera
  • redesigned cooling-camera (similar Kochic design) for 135 film
  • thermical isolated by acryl-plate window of 2cm thickness

  • Description:

    One-stage peltier-cooling with secondary water-circuit instead of the dry-ice chamber of orginal Kochic-design.The cooling-current is about 15A at minimum film temperature of -30 degree Celsius. The inner film-chamber can be filled with dry Inertgas. No cutting of the film necessary.

  • No usage today, the camera is replaced by CCD.

    first CCD Camera
    image 23kB: CCD-camera 1
  • manufactor and type: OES LcCCD11, Dr. F. Fleischmann (Germany) 1994
  • Kodak KAF400 grade 1 CCD 768x512 pixel with 9x9μ size
  • redesigned housing, peltier-cooling and selfmade shutter

  • Description:

    With redesigned housing we also can use lenses with C­Mount or Nikon-bajonet. The shutter and shutter-electronics are selfmade. Shutter-electronics are able to drive a filter-wheel too. Connected to computer with ISA-slot.

    No usage today, because of software is running under DOS only.

    second CCD Camera
    image 28kB: CCD-camera 2 standard forced air cooling image 23kB: CCD-camera 2 assembled with secondary cooling equipment image 29kB: CCD-camera 2 assembled with secondary cooling equipment
  • manufactor and type: Roper Scientific Princeton Instruments Versarray 1300B
  • CCD: Marconi EEV 36-40 1340x1300 Pixel
  • 4-stage strong Peltier-air-cooling with fan
  • Shutter, selfmade upgrade to 45mm diameter

  • Description:

    This scientific CCD-camera normaly used in physical and biological laboratories. The amateur astonomers know less about this camera type. Therfore it is not able to control this camera with amateur-like astronomical image-processing software, like astroart, maxim-dl and others. The software including is designed for spectographs and microscopic use and less for astonomical equipment, but with a remarkable user-development documentation, you are able to write a user Plug-in.

    Now, our own software is optimised for astronomical use. It convertes all images to FITS-format. In future we are able to drive filter-wheels computer-controlled with build-in digital IO of the camera.

    Orginally the camera is equipped with Nikon-Bajonet and a 35mm shutter, less for long focus range. For that reason you have vignetting in image-edges, you need a larger shutter. Using our selfmade dry-box you get no ice-crystals at front window of the high evacuated CCD-package.

    The excellent technical specifications are the reason for our decision to this type of camera. Professional astronomers at Konkoly observatory (Hungary), at Rhozen Observatory (Bulgaria) or at Lulin observatory (Taiwan) also used this camera with bigger telescopes (links see german version).

    third CCD Kamera
    image 55kB: Webcam with f/1 cine-lens image 64kB: some C-mount lenses usable image 62kB: Webcam with NIKON-Coolpix wide-angle adapter
  • manufactor: Phillips
  • type: Webcam "TOU-CAM Pro "
  • assembled with new selfmade housing
  • and additional C-Mount lens adapter

  • Description:

    The camera needs USB-Port only. Coming with exemplary software. For astronomical use we apply IRIS freeware. Only usable for bright objects as Sun, Moon and Planets, not for deep-sky work. Don't make electrical modifications, it is not worth while.

    Mintron and Watec
    Two little CCD-videocams (black and white) without cooling, the well known types MINTRON MTV12V1-EX and WATEC 120N. Additional feature of the cams is hardware-summing of single frames. Exposuretime up to 2.5 seconds (Mintron) or 10 Seconds (Watec) are possible.


    The Mintron comes with auto-exposure feature, perfect for use with a very small robotic telescope. Such a telescpoe with fast optic is under construction now. The Watec + focal reductor lens is usefull as electronic eyepiece, special use with H-alpha-filter to visualize bright nebulae and presentation of sky objects with video beamer. A pinnacle video frame grabber with USB interface is used for connecting to PC.

    Other Instruments

    laser collimator
    image 21kB: laser collimating equipmentWe are able to collimate our RC-optic exactly under daylight condition.
  • The instrument is selfmade after notations of R. Pressberger

  • Description:

    In contrast to commercial instruments, you are able to minimize tilt-error and shift-error of both mirrors. Applicable to any kind of Cassegrain-system. Needs no fine-adjustment with night-sky star.

    Sun Protuberances viewer
    image 18kB: Sun protuberance viewer
  • manufactor: BAADER Planetarium (Germany)
  • 10 Å narrowband H-alpha-filter

  • Description:

    Not usable, malfunction of H-alpha-filter because of over age after 7 years.

    Weather-Satellite receiver
  • manufactor: GRUNDIG (Germany)
  • reception of METEOSAT images

  • Description:

    Includes a 23-elements YAGI-antenna and a receiver-box, like videosatellite equipment. Output of videosignal conectable to TV-monitor. Usable for cloud forcastig.