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   TAL-100RSM telescope's service manual
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TAL-100R' main page


1. General directions
2. Specifications
3. Standard equipment
4. Design of telescope
5. Optical train
6. Preparation for operation
    6.1. Telescope assembling
    6.2. Telescope balancing
    6.3. Precautionary measures
7. Order of operation
    7.1. Operation with telescope
    7.2. Photographic observations
    7.3. Telescope and atmospheric conditions
8. Maintenance
9. Rules of storage
10. Acceptance certificate

Supplement. Table of close stellar pairs for testing image quality of telescope

1. General directions


Never attempt to directly view the Sun with any telescope, including finderscopes and binoculars. Instant and permanent eye damage or blindness will result. Never allow children to use the telescope during daylight hours unless they are supervised by a responsible adult conversant with this real danger.

If you decide to make an observation of the Sun directly, It is necessary to reduce an aperture with the help of diaphragm and to use a black solar light filter.

The telescope can operate normally at the ambient temperature from 30°C to minus 30°C.

Telescope TAL-100RSM (hereinafter in the text referred to as “telescope”) is a precise powerful amateur astronomer telescope. It demands a careful handling and certain knowledge in the field of astronomy. Only in this case user will be full satisfied.

When buying the telescope one should pay attention to the package safety ensured by the seal of the manufacturing plant. After unsealing the case one should check compliance of the complete set denoted in the list of enclosure. Prior to using the telescope one gets acquainted with its handling and order of operation.

2. Specifications


Effective aperture

100 mm

Focal length

1000 mm

Focal ratio


Angular field of view at various magnifications



40x & 1°


100x & 0°28'


155x & 0°15'

Resolving power


Limiting visual magnitude


Range of slow-motion control on the axes within


Rotation of the telescope:


   - in right ascension

360° (24h)

   - in declination 


Operation limit by latitude 


Angular field of finderscope

Magnification of the finderscope 


Voltage of the supplying mains (TAL-100RM), V

220 (110) ±10%

Current frequency (TAL-100RM), Hz

50 (60)

Dimensions, mm


Dimensions of the cardboard case, mm


Weight of telescope TAL-100R / TAL-100RM, kg

17 / 22 kg

Weight of the telescope TAL-100R / TAL-100RM packed

20 / 25 kg

3. Standart equipment





Supply unit


Eyepiece of f=25 mm




Equatorial mounting


Hinged clips








Bundled conductors


Accessories and Parts


Eyepiece of f=10 mm


Eyepiece of f=6.3 mm




Neutral light filter (gray, lunar)


Black light filter (solar)










Fuse link VPT 6










Service manual


* Telescope can be completed with a metal pier (TAL-100RSM) or tripod (TAL-100RSMT)

4. Design and principle of operation of telescope

The telescope (Fig.1,2) consists of three basic units: the telescope tube, equatorial mounting, and pier with supports or tripod.

General view of the TAL-100R telescopeGeneral view of the TAL-100R telescope

Fig. 1-2. General view.
1 - telescope tube; 2 - optical finderscope; 3 - eyepiece set;
4 - nut; 5 - bundled conductors; 6 - support;
7 - cord, 8 - supply unit; 9 - pier;
10 - equtorial mounting.

The tube 1 is the basic part of the telescope, which embodies the optical units: objective lens, eyepieces, and finderscope.

Eyepiece parts 3 consist of the following units: focusing mechanism, diagonal mirror, set of Plossl eyepiece f=25mm; f=10mm; f=6.3mm mounted with the fitting place of 31.8 mm (1.25").

Finderscope 2 is a scope with 6X magnification and field of view of 8°. It is completed with blind (Fig.1) which is mounted on objective lens.

The equatorial mounting (Fig. 3) consists of polar axis 2 and declination axis 6 perpendicular to the polar axis.

Equatorial mounting of the TAL-100R telescope

Fig. 3- Equatorial Mounting.
1 - circle of hour angles; 2 - polar axis; 3 - screw of axis brake;
4 - folding clips; 5 - handwheel of slow-motion mechanism; 6 . declination axis;
7 - circle of declinations, 8 - counterweights; 9 - handle;
10 - bracket with scale of latitudes; 11 - electric clock drive; 12 - handwheel of polar axis.

Fastened on the end of the declination axis is a saddle with hinged clips 4 in which the telescope tube is mounted, fastened on the other end of the axis are counterweights 8 which can move along the axis for balancing the telescope tube.

The casing of the polar axis is fastened on bracket 10 (Fig. 3) provided with a scale of latitudes by which the polar axis is set to the latitude of the observer's site.

The southern (lower) of the polar axis embodies electric clock drive 11, the northern (upper) end embodies the casing of declination axis 6.

Both axis are provided with setting circles which shows an hour angle and declination of the object visible in the telescope field of view. Setting circle 7 on the declination axis which shows the object declination is figured from 0 to 90° with a division value of 2°. Circle 1 positioned on the polar axis (the circle of hour angles) is figured from 0 to 24 hours with a division value of 10 min.

The declination axis has braking screw 3 and mechanism 5 of slow motion which moves the tube in the range of ±4°. By using this mechanism it is possible to correct the position of the object in the field of view. The equatorial mounting is placed to the pier or tripod.

Pier 9 (Fig. 1) consists of one tube on which three legs are fixed.

The tripod (Fig. 2) allows to adjust a height of telescope and to fix each leg of stops 1 and 2.

Supply unit 8 (Fig. 1) (a step-down transformer) is designed for convertering of voltage supply mains 220V, 50 Hz or 110B, 60Hz in to the voltage supply 1 2V which is necessary to supply a safe operation of telescope.

5. Optical train

The telescope tube (Fig.4) is a refractor with achromatic objective lens 1. It provides a high quality of image with a resolution limit of diffraction level.

Telescope tube is completed with three changeable eyepieces 4 f=25mm; f=10mm and f=6.3mm.

For easy observation of celestial objects near by zenith an eyepiece set of telescope turned to optical axis by 90° with the help of plane diagonal mirror 2. If it is necessary one should use a finderscope consisted of objective lens 5, reticle with cross-hair 6 and eyepiece 7 that to allow locating an object in the center of field of view.

Optical scheme of the TAL-100R telescope

Fig. 4. Optical train and diagram of mounting a camera (below).

6 . Preparation for operation

6.1. Telescope assembling

Prior of assembling the units and parts should be cleaned from the sluicing compound of the plant.

The telescope is assembled in the following way.

Three supports provided with captive screw are fixed to the lower end of the pier through hollers. The equatorial mounting by the scale of latitudes to the latitude of the observer's site and fixed with handle 9 (Fig. 3).

The telescope tube is mounted on the supports of the saddle and fixed by means of two clips with the help of hinged screws.

The finderscope is mounted on the tube in two rings and fixed with six screws available on the rings.

In transportation and storage a hole on the eyepiece tube is plugged with a stopper which should be removed and put in the case in the preparation for operation.

A toggle switch of the supply unit is to be set in position OFF.

Connect bundled conductors 5 (Fig. 1) to the clock driver and to supply unit through a socket designated with 1 2V, connect a plug of cord 9 of the supply unit to the mains of 220/110V. Set the toggle switch of the supply unit in position ON, set the toggle switch of the drive in position ON. A light indicator on the ( lock driver must light.

6.2. Telescope balancing

For smooth motion of the telescope and reliable operation of the slow motion screws it is important to balance its movable parts on the axes o the equatorial mounting.

For this purpose one should set the telescope tube in the horizontal position, unscrew the screw of barker 3 (Fig. 3) of the declination axis and, holding slightly the tube by hand, see to it whether it remains in the indifferent equilibrium. If the tube is not in balance, undo the screws of the clips which fix the tube and move the tube along its axis until it will be in balance. After that screw in the screws of the clips.

For balancing the telescope relative to the polar axis it is necessary to set the declination axis in the horizontal position.

Then it is necessary to slacken each of three screws 1 2 after moving cap 11 of the clock drive (Fig. 5). Holding the axis by hand, see to it whether the telescope is in balance about the polar axis. If the telescope is not in balance, move counterweight 8 (Fig. 3) along the declination axis. After balancing tighten screw 12 of the friction clutch (Fig. 5) on the polar axis so that the telescope can not rotate easily.

The adjustment of the friction clutch is considered to be finished if the telescope tube moves due to the minor effort of the hand.

When mounting the various devices on the telescope, for example, a camera, it is required to balance the telescope additionally.

6.3. Precautionary measures

The rate of the fuse link mounted in the supply unit must be compliance with the rate denoted under the fuse link holder.

Mount the fuse link only after complete disconnection of the supply unit from the mains.

Connect the bundled conductors to the watch drive and to the supply unit only when the supply unit is disconcerted from the mains.

Clock drive of the TAL-100RM telescope

Fig. 5. Clock drive
1 - worm gear wheel; 2 - cap; 3 - screw; 4 - handwheel; 5 - screw; 6 - screw;
7 - motor; 8 - screw; 9 - worm with gear wheel; 1 0 - worm wheel; 11 - cap; 1 2 - screw; 1 3 - cover

7. Order of operation

7.1. Operation with telescope

Before mounting the telescope it is required to choose the place and prepare the site. It must be even and solid. Mount the telescope on the site and check it for tenable stability.

After mounting the telescope it is required to set parallelism of the optical axes of the telescope tube and finderscope. For this purpose one should insert a reticle 7 (Fig.5) into eyepiece f=25mm and to insert the eyepiece together reticle into eyepiece set. Then the telescope is pointed to the remote object. The position of the telescope is fixed by means of the screws of the brakes of the axes.

Then, by operating with the setting screws of the rings of finderscope, one brings the chosen remote object to the centre of the finderscope view field. This operation is performed only once. In the future before observation only the parallelism of the optical axes of the telescope and finderscope is checked.

The celestial sphere together with astronomical objects performs the visible motion about the celestial axis. Therefor the telescope is provided with equatorial mounting. Being set correctly, this mounting makes it possible to perform to the celestial object tracking. After pointing the telescope to the object the observer can keep the object in the view field center for a half a haul by rotating slowly the micrometer screw of the polar axis.

In order to avoid guiding collection in declination, the polar axis of the telescope should be set parallel to celestial axis. In this case the north (upper) end of the polar axis faces the celestial pole positioned near Polaris (a Ursae Minoris). For visual observations it is enough to incline the polar axis at an angle equal to the latitude of the observing site and direct it approximately along the line the South - North. With such setting of the telescope the object will 'deviate' step by step in declination (it is lifted or lowered in the view field). This error is corrected occasionally by means of the micrometer screw of the declination axis.

For photographic operations and in the cases when the telescope can be set stationary, the polar axis of the telescope should be set precisely. For this purpose one observers any blight star in the East, then in the South and makes notice of the direction of the star displacement.

If in the observation of the star in the East it is disposed in the telescope view field so that in its tracking the upper end of the telescope tube sinks slowly, the north end of the three polar axis should be somewhat lifted.

Accessories of the TAL-100R telescope

Fig. 6. Accessories.
1 - cap; 2 - eyepiece; 3 - light filter; 4 - wrentch; 5 - napkin; 6 - blind; 7 - rericle; 8 - adapter

If the upper end of the tube Is lifted step by step, the north (upper end of the polar axis should be lowered.

For precise setting of the axis by azimuth one observes the star near the meridian circle (above the South point) in the same way. If in the star tracking one has to lower slowly the upper end of the telescope tube, the north end of the polar axis should be displace to the West.

If in the process of the star tracking the upper end of the telescope tube I lifted, the north end of the polar axis should be displaced to the East.

In 20-30 minutes of such observations one can set the polar axis so that the star will remain on the cross-hairs for 10-15 minutes without correction in declination.

After precise setting of the polar axis one can set the declination and haul elides which must help to search the objects invisible with a naked eye or even through the finderscope.

First of all one should set the hour elide which is fixed on the polar axis. After fine setting of the polar axis set the declination axis horizontally. The horizontal setting should be checked with the aid of a level. After setting the axis one sets the haul elide so that “0” is found against the index. Fix the circle by means of brake.

For setting the declination circle fixed on the declination axis one should find the declination of two-three bright stars in the star catalogue or make use of the' declinations of the planets. With the help of the finderscope one brings the star or the planet to the center of the field of view of the telescope at maximum magnification. After that one sets the declination of the required star against tin1 index. The circle is to be fastened with a screw. Then one makes attempt to lind the second star by its declination. For this purpose one slackens the screws of the axis brake and adjusts the telescope so that the declination of the star to be sought is set on the declination circle. Fix the declination axis by rotating the telescope tube slowly clockwise hound the polar; bring the star to the center of the telescope field of view. After checking of the circle setting one tightens it with a nut.

In order to avoid resetting of the polar axis and elides one should choose a solid horizontal site. Best of all it is made of some concrete of 1.5x1.5 m size. The position of three supports of the telescope pier should be marked on the site. The telescope is mounted according to the marks on the concrete site.

7.2. Photographic observation

Photographing star fields is carried out with the use of the telescope in the main focus. To make it one should use a small size 35 mm camera or other devices having fitting thread of 42x1.0 mm or 42x0.75 mm. To mount a camera it is necessary to remove an eyepiece set 3 (Fig.1) from tube and to mount a camera with 42 x 1.0 mm thread. If it is necessary, one should use an adapter 8 (Fig.6) to mount a camera with 42 x 0.75 mm thread. Mounted a camera one should make a focus it and to balance the telescope.

The exposures, which are required for photographing the star fields, are tenths of minutes without interference of the street lighting. Therefore, for this period of time one should see to it that the camera follows the sky precisely in its diurnal rotation. Near the center of the field of view of the camera one chooses the bright star to which the telescope is pointed. To keep the star on the reticle cross hairs of the finderscope is the problem for an observer for the whole period of exposure. As the cross-hairs of the finderscope is not illuminated, the image of the guide stair should be slightly defocused in order to cross a light circle of the unsharp image of the star by the cross-hairs and to keep the star in this position for the period of exposure.

One applies minor corrections for a clockwork drive with the help of handwheel 4 (Fig.5) keeping the star on the cross hairs for the whole period of exposure. One corrects the position of the guide star with the micrometer screw of the declination axis if necessary. To obtain the minimum corrections in declination the polar axis should be set as precisely as possible to the celestial pole. One should remember that if the polar axis is set incorrectly, even in the case when the star image is kept on the cross-hairs, the images of the stars at the edges of the field of view appear as dashes.

7.3. Telescope and atmospheric conditions

At high magnifications together with the increase of the visible dimensions of the object the disturbances due to atmosphere are increased. They are expressed in great blurring of the images of the distant objects, in scintillation and blurring of the star images.

The observation in the cold seasons is possible when all telescope parts acquire the ambient temperature. For air circulation inside the telescope tube there is a hole plugged with a stopper in the cell of the primary mirror. In operation the stopper should be unscrewed from the cell.

But in observations outdoor the great disturbance of atmosphere may take place at nights, that lead to bad images of the celestial objects.

It is quite possible that at those nights the observations of the fine details of the planets and of the Moon are unsuccessful.

It is apparent that the observations with the aid of the telescope through the window are senseless as the rough surfaces of the window glasses distort the images.

In case of precipitation and stopping of operation the telescope together with supply unit must be covered.

8. Maintenance

For faultless operation the telescope should be kept in cleanness and protected against mechanical damage. The metal surfaces are periodically dusted by using clean soft napkins, then wiped with a napkin impregnated with acidless vaseline, after that with a dry napkin.

The lenses of the eyepieces are wiped with a dry linen napkin. The fat spots are removed with a cotton wool piece impregnated with alcohol.

oik- should dismantle the optics only in case of necessity. In non-operating position the telescope tube must be constantly covered with a cap and the eyepiece one is to be plugged with a stopper.

9. Rules of storage

It is recommended practice to store the telescope in the heated room with Ihc relative humidity of maximum 80% at the temperature from to 40° C.

10. Acceptance certificate

Telescope TAL-100RSM (TAL-100RSMT), serial N .......... is found fit for service.

Date of manufacture and slushing ____________

Signatures ________________________


Table of close stellar pairs for testing image quality of the telescope

Name of star


Magnitude, m

Visible distance, ang. s.


h, m

ang. degrees, ang. min.




































Ursa Major












Ursa Major





























































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