ASTRO-PHYSICS 400QMD User manual

ASTRO-PHYSICS
400QMD GERMAN EQUATORIAL MOUNT WITH
DUAL AXIS QUARTZ MICRO-DRIVE (400QMD)
MODEL 400QMD PARTS LIST
1 400QMD Equatorial Head with stepper motors on right ascension and declination axes
1 Stainless counterweight shaft with washer stop and black plastic knob (5/16-18 threaded rod)
1 Dual axis quartz micro-drive control box
1 “Y” connector cable
1 D.C. power cord (cigarette lighter adapter)
3 Black plastic knobs with ¼-20 threaded rod
1ea. Hex keys 3/16” and 5/16”
2 Red caplugs
1 Piece of Velcro (to attach hand controller to surface of your choice)
In order to fully assemble and use your mount, you will need the following items sold separately: cradle plate, pier or
tripod, portable rechargeable battery pack and counterweights. Several sized and types are available for your
selection. Many of these items will be discussed throughout these instructions.
Several additional options will help to enhance your observing experience: polar axis telescope with illuminator; high
resolution mounted encoders and JMI computerized digital setting circles, Santa Barbara Instrument Group CCD
imaging camera/autoguider.
INTRODUCTION
If you were to take a long exposure photograph with
Polaris (often called the North Star) in the center of the
field, you would discover that all stars seem to revolve
around Polaris. This effect is due to the rotation of the
earth on its axis. Motor driven equatorial mounts were
designed to compensate for the earth’s rotation by
moving the telescope at the same rate and opposite to
the earth’s rotation. When the polar axis of the
telescope is pointed at the celestial pole (polar aligned)
as shown in the diagram on the right, the mount will
follow (track) the motions of the sun, moon, planets,
and stars. As a result, the object that you are
observing will appear motionless as you observe
through the eyepiece or take astrophotos.
For visual observation, a rough sighting of Polaris
through the hole in the polar axis is fine. However if
astrophotography is your goal, accurate polar
alignment is critical.
We recommend that you familiarize yourself with the
assembly and basic operation of the mount indoors.
The temperature will be comfortable, the mosquitoes at
bay, and you’ll have enough light to see the illustrations
and read the manual. Please take particular note of
counterbalancing, use of the clutches and operation of
the hand controller.

ASSEMBLY INSTRUCTIONS
Please read all instructions before attempting to set up your 400QMD mount. The Model 400 is very rugged;
however, like any precision instrument, it can be damaged by improper use and handling. Please refer to the
diagrams below for illustrations of both sides of the mount. The parts are labeled so that we can establish common
terminology.
The following terms and abbreviations may be used interchangeable in these instructions:
Polar axis = right ascension axis = R.A. axis = R.A. housing
Declination axis = Dec. axis = Dec. housing

ASSEMBLE PIER OR TRIPOD
Begin by assembling the pier or tripod at the observing location.
ADJUSTABLE ALUMINUM TRIPOD: Extend the legs to the desired height; secure with the locking levers. Adjust the
distance between the legs. Place the legs far enough apart to provide a solid base of support. Please refer
to the diagram below.
ADJUSTABLE HARDWOOD TRIPOD: Remove the tripod from its carrying case and attach the shelf to each of the
three legs with the knobs provided. Adjust legs to the desired height and spread. Lock in position with the
hand knobs. Please refer to the diagram below.
PIER: Slide the three legs onto the nubs of the base. Place the pier post on the base and attach the tension rods.
The turnbuckles should be drawn tight until the whole assembly is stiff enough to support your weight
without movement. Please refer to the diagram below.
ASSEMBLE MOUNT TO PIER OR TRIPOD
In order to track the motion of astronomical objects, the polar axis must be positioned so that an imaginary line drawn
through the hollow shaft points toward the celestial pole. At this stage of the assembly process, you want to position
the mount so that it points roughly north. Place the mount into the top of the pier or tripod so that the threaded R.A.
axis hole is on the south side of the pier/tripod. Line up the holes of the mount and pier/tripod. Screw in the three
hand knobs to hold the mount in place.

ALTITUDE AND AZIMUTH ADJUSTMENTS – ROUGH POLAR ALIGNMENT
Follow these instructions if you want to rough polar align your mount. If not, you may skip this section and move onto
“Assemble Cradle Plate and Counterweight Shaft.” You may make these adjustments with the telescope mounted or
not, according to your preference. If you plan to mount your scope at this stage, refer to the “Assemble Cradle Plate
and Counterweight Shaft” section first.
1. If you examine the polar axis assembly, you will see that center of the polar shaft is hollow. You may need to
rotate the internal declination shaft by moving the top of the declination axis (or the cradle plate if it is attached) to
align the sight hole that has been drilled into it. Now, you can look through the shaft to the other side. The end of
the R.A. axis is threaded to accept the optional polar alignment telescope. You do not need the polar alignment
scope for this part of the process.
2. Loosen the two black plastic clamp knobs on each side of the mount. Use the 5/16” hex key to loosen the 3/8-16-
socket head cap screw on the side of the mount base. If your scope is mounted, support its weight with your
other hand since you are loosening a critical bolt.
3. Your goal is to sight Polaris when looking through
the polar alignment sight hole in the center of the
polar axis. You will need to make altitude and
azimuth adjustments to the position of the mount.
4. Altitude (latitude) adjustments: Move the polar axis
up or down with the large altitude adjustment knob
located at the rear of the mount assembly.
5. Azimuth adjustments: Move the entire pier or tripod
east or west until the mount is oriented
approximately towards the pole. Use the two fine
azimuth adjustment knobs, one on each side of the
mount, to make fine adjustments in azimuth. You
must back off the opposing azimuth knob in order
to move the other knob in that direction. Please
refer to the diagram on the right.
6. You will continue to make adjustments in azimuth and altitude until you can see Polaris through the polar
alignment sight hole. At this point, you have achieved rough polar alignment, which may be sufficient for most
casual visual observations. When the R.A. motor is engaged, it will compensate for the rotation of the earth and
keep the target object within the eyepiece field of view. Your target object will slowly drift since polar alignment at
this stage is only approximate. However, you can make corrections with your hand controller, as we will discuss
later.
7. If rough polar alignment is sufficient, snug the two black plastic clamp knobs and the 3/8-16 screw to lock the
mount into position. If you require more exact polar alignment, proceed to the next section.
FINE POLAR ALIGNMENT – Not necessary for casual observation
Follow these instructions if you want to fine-tune the polar alignment of your mount. If not, you may skip this section
and move onto “Assemble Cradle Plate and Counterweight Shaft.”
1. Polar alignment telescope – The north celestial pole can be viewed through the polar alignment with our optional
polar alignment telescope. Please read the instructions sheets for the polar alignment telescope.
2. If you do not have a polar alignment telescope, you may use the star drift method. Please refer to the
recommended reading list at the end of this manual.
3. When the proper alignment has been achieved, snug the two plastic clamp knobs and one 3/8-16 screw lightly to
secure the polar axis and recheck alignment. If no movement has occurred, finish tightening the screw as much
as possible to prevent movement when the telescope and counterweights are attached.
IMPORTANT: Failure to tighten the side screw can cause the axis to slip, with resultant damage to the mount.

ASSEMBLE CRADLE PLATE
Attach the cradle plate to the top of the declination axis with the four ¼-20 screws provided with the mount. When you
have finished your observing session, the cradle plate may remain attached to the declination axis or removed as
desired.
ASSEMBLE COUNTERWEIGHT SHAFT
IMPORTANT: Always attach the counterweights before mounting the telescope to prevent sudden
movement of an unbalanced tube assembly, which may cause damage or injury.
1. Thread counterweight shaft onto the Dec. axis.
2. Remove the hand knob and washer from the base of the counterweight shaft. Add sufficient counterweights (6 or
9 lb. counterweights are available) to the counterweight shaft to balance the telescope you intend to use. Always
use two hands to attach or move them on the shaft. Reattach the hand knob and washer to the end of
counterweight shaft. This will help to prevent injury if someone accidentally loosens the counterweight hand
knob.
A firm tightening of the counterweight knob will not damage the surface of the counterweight shaft. The pin that
tightens against the stainless counterweight shaft is constructed of brass. Likewise, the bronze sleeve that has been
press fit into the center of the counterweight will prevent marring of the shaft as you move the counterweights.
When you remove the counterweight shaft, a threaded black anodized piece may remain attached to your
counterweight shaft. This is of no concern as it can be threaded back onto the mount.
OPERATION OF THE MOUNTING
You can move your telescope to various objects either by grasping the telescope tube and moving it manually or by
pressing the buttons on the controller.
Clutch Knobs: There are two black anodized knobs, one located on the R.A. axis and the other on the Dec. axis. If
the knobs are loosened, the axes can be swung around freely. If the telescope is properly counterbalanced, the
clutches can be left partially engaged. This will allow you to move the telescope easily without constant clamping and
unclamping the axes. For astrophotography, snug up a bit more. Please do not over-tighten these knobs. If the
knobs are very tight and you try to move the telescope manually by grasping the tube (as you probably do habitually),
you will place severe strain on the driving gear teeth. This word of caution is true of any mount.
Balancing Your Telescope: For proper operation, the telescope must be adequately counterbalanced. Start by
balancing the tube assembly. Tighten the black R.A. axis clutch clamp; loosen the black Dec. axis clutch clamp so
that the telescope tube rotates on the declination axis. If you are using the dovetail plate, loosen the two side knobs
and move the sliding bar, with scope attached, forwards and backwards. If you are not using the dovetail plate,
loosen the mounting rings and slide the tube up or down. The scope is balanced when it stays level with no clutch
drag. Now, tighten the declination axis with the clutch clamp and loosen the R.A. clutch clamp. Move the
counterweights up or down to achieve balance in R.A. Remember to allow for the extra weight of diagonals,
eyepieces, and finderscopes. If the scope moves by itself, even when the clutches are loose, the scope is not fully
counterbalanced precisely. A small amount of imbalance on the East side is permissible and even desirable for
astrophotography and imaging.
When the mount is properly aligned, it is possible to take unguided astrophotos for several minutes without trailed star
images.

OPERATION OF THE QUARTZ MICRO-DRIVE CONTROLLER
The push button controller contains all the circuitry for driving the two motors. It will be operational when attached to
both the motors of the mount and a power source. There is no on-off switch. Power requirements are 12 to 16 volts
dc, 800ma. This can be supplied from a battery or an AC to DC converter.
If the voltage falls below 10 volts, the power light will go out and the motors
will quit running.
A very accurate quartz clock specifically calibrated for the drive gear is an
integral part of the controller. The calibration is made to the King sidereal
rate, which compensates for atmospheric refraction over a large part of the
sky. With this tracking rate, it is easier to maintain critical guiding at high
power. For the most sophisticated tracking of celestial objects, the
controller has a built-in provision for attaching a CCD imaging
camera/autoguider. Using the autoguider function, it is possible to take
long exposure astrophotos totally unattended. You can walk away from the
setup to enjoy other observing activities while your astrograph is in
operation.
The controller contains circuitry for storing the periodic error of the worm.
Depending on how well the initial guiding was done during the record
period, a very significant increase in guiding accuracy can be expected.
CABLES: Place the DC power cord into the phono plug outlet of the R.A.
motor box. Plug the short length of the “Y” cable into the R.A.
motor box and the long length into the Dec. motor box. Complete
the cable assembly by joining the control box cable to the “Y” cable.
The control box and motors are designed to work at 12 volts DC.
Suggested power sources include: portable rechargeable battery
pack, auto battery, or power converter for 110 volts with a minimum
output of 800ma. at 12VDC.
DRIVE ROTATION: If you are operating the 400 mount north of the
equator, the HEM (hemisphere) switch must be set to “N”. If south
of the equator set the switch to “S”.
PUSH BUTTONS: The four red buttons are arranged so that the left and
right buttons control the movement in right ascension and top and
bottom buttons control the declination. This is the normal
orientation of objects in the eyepiece field. If the star moves down
when you push the “N” button, move the DEC REV (Dec. Reverse)
switch into the opposite position. Pushing the right hand button “E”
should cause the star to move to the right. If it moves to the left,
move the RA REV (RA Reverse) switch to the other position. When
properly set up, the controller buttons will cause the object to move
according to your orientation at the eyepiece.
DRIVE RATES: The control box has three drive rates to choose from: SID
(sidereal), SOL (Solar), and LUN (lunar). Select the position
appropriate for the object under observation.
King Sidereal: Tracking rate for observing planets, stars
galaxies and other distant objects.
Solar: Tracking rate for observing the sun.
Lunar: Tracking rate for observing the moon.
SLEW RATES: There are two slew (rates): 8x and 16x slew rate. The slew
rates are for positioning objects in the field. Use the guide rates for
fine guiding at high powers during astrophotography. Move the
switch to select the mode that you prefer.

GUIDE RATES: If you wish to engage the fine guiding rates of 1x, 0.5x, and .25x, move the first switch to GUIDE and
the second switch to the 1x, .5x, or .25x position.
DECLINATION BACKLASH CONTROL: When using the 1x, .5x, and .25x guide rates in declination, you may find
that there is a delay when attempting to reverse the motion of the star. Normally declination drift is only in
one direction, and will require correction with only one button. However, occasionally it may be necessary to
reverse the motion. The multiple gear train inside the drive motors takes a considerable number of pulses to
unwind and rewind in the opposite direction. To compensate for this, we have included a circuit that pulses
the motor very rapidly for a moment before continuing at the slower rate. Because the amount of delay varies
with each motor, we have installed a 10-position switch which can be used to dial in the exact amount of
compensation. Starting from the left, engage one switch at a time into the up position until the delay at .25x
guide rate is minimum. If too many switches are engaged, the star will over shoot the desired position.
PERIODIC ERROR MEMORY (PEM): The drive controller contains a very sophisticated periodic error compensation
circuit. Because the majority of the periodic error is due to the worm and is quite predictable, it is possible to
significantly reduce it by simply having the controller “memorize” your button inputs and automatically play
them back for each cycle of the worm. This circuit has some unique features that makes it easy to operate
and almost totally foolproof.
To start the process of recording the periodic error, align your telescope accurately on the pole so that you get
minimum R.A. and Dec. drift. Place a medium brightness star on the crosshair at moderately high power so
you can easily see the R.A. gear drift. Be sure that the night is steady enough with minimum atmospheric
motion and pick a star near the zenith to minimize atmospheric refraction errors. The recording process will
take about 6.5 minutes to complete.
When you are ready to begin, be sure that the star is on the crosshair, and slide the play/record switch into
the “record” mode. The green LED will come on for the 6-minute period, and will extinguish at the end of the
recording period. During this 6.5-minute period it will be necessary to keep the star on the crosshair. Every
button input will be recorded. Avoid trying to guide out any atmospheric scintillation, since this will add a
random noise error into your final guide rate. If an ST4 autoguider is available, it can be used to guide, and
the controller will faithfully remember each error correction that it makes. An autoguider is extremely
accurate, and will place into the memory a very smooth correction of the gear error.
When you wish to play back the recorded corrections, slide the play/record switch into the “play” mode. The
controller will automatically play back the correct portion of the worm error. It is not necessary to place the
rate switches into the same position that they were recorded in. For the smoothest results, however, it is
advised to record and play back in the .25x position. The controller can be slewed in the 8x and 16x mode at
any time without losing track of the periodic error. The playback can also be turned on and off at any time
without losing track of the gear position.
A most valuable feature of this circuit is that it automatically compensates for any drift inadvertently introduced
by the operator in the process of recording the gear error. For instance, if the mount was not properly polar
aligned in altitude, the right ascension drift rate would be in error. The circuitry automatically subtracts this
slow drift from the memory, so that the overall long-term drive rate remains exactly at the King rate. This way
the compensated driving rate will always be correct for any other position in the sky and for any other time
that the mount is set up in the field. When the mount is properly polar aligned, it is possible to take 15 to 30
minute unguided astrophotos without trailed star images. For more critical exposures, the controller memory
allows the astrophotographer to check the guide star only occasionally during a long exposure.
LED KNOBS: There is an LED output available on the 400 Dec. axis motor housing as shown on Diagram 2. You
may insert your LED reticle to this plug. Brightness can then be controlled using the MIN to MAX (minimum to
maximum) setting of the LED knob.
AUTOGUIDER CONNECTION: If you own a Santa Barbara Instrument Group (SBIG) ST-4 or ST-6 Star
Tracker/Imaging system, connect it to the RJ11 phono plug input of the controller via a TIC (Tracking
Interface Cable) produced by SBIG. You may purchase the cable directly from us (our part #CABTIC) or
directly from SBIG. This cable will have a DB15 female connector on one end and an RJ11 plug on the end
that inserts into our controller.
To operate the SBIG ST-7 or ST-8, you will need the ST-7 cable available from SBIG. This is the same cable
that is offered for the Celestron Ultima. It has a DB9 male connector on one end and an RJ11 connector that
inserts into our controller.

GUIDING YOUR ASTROPHOTOS
The natural tendency of astrophotographers is to push the directional button of the controller in the direction he or she
wants the guide star to move until the star has centered itself in the guiding reticle. This method often results in
overshooting the center of the reticle since the reaction time to let go of the button is often too late. By the time the
gears in the drive motor have reversed and are driving again at the normal guiding rate, the star has moved past the
center of the reticle. Then the opposite button is pushed to move the guide star back in the opposite direction toward
the center and the same overshooting may occur.
The proper way to guide (and this will apply to almost any commercially available mounting) is to pulse your
correction, much like the SBIG ST-4 does in its auto-guiding operation. Pulse the button for only a fraction of a
second and note the new position of the guide star. If it has not moved far enough, pulse it again. Normally, it takes
only one or two pulses to re-center the star. Declination drift can be eliminated by proper polar alignment. Fine
adjustment can be made by noting the direction of Dec. drift and, using the azimuth adjusting screws, by moving the
star in the opposite direction. Several of these iterations can be made until the Dec. drift is in the opposite direction.
R.A. drift will occur if the polar altitude is set wrong. If the drive rate seems to be too fast (star drifts eastward), the
altitude is set too low. Adjust it upwards until the R.A. drift stops or reverses. Both altitude and azimuth will affect
each drift rate, so some back and forth adjustment may be necessary.
MOUNT MAINTENANCE AND ALIGNMENT
Under normal operating conditions, no maintenance is required. Your 400QMD is a precision instrument with very
accurate worm and wheel adjustments. Please be careful if you place the mount on a flat surface, i.e. the ground or
trunk of your car. The gear alignment may be affected if the R.A. and Dec. motor/gear box assemblies sustain undue
lateral force. This is true of any fine instrument. We suggest that you transport and store the mount in a case or in a
well-padded box
NOTE: If your battery runs low, the declination motors will stop first, through the R.A. will continue to drive until
the power is drained.
If any problems occur, please don’t hesitate to contact Astro-Physics for assistance.
ASTRO-PHYSICS INC
11250 Forest Hills Road
Rockford, IL 61115
Telephone: [phone]
Fax: [phone]
www.astro-physics.com
Recommended reading list from our staff:
The Backyard Astronomer’s Guide, Terence Dickinson and Alan Dyer, Camden House Publishing, 1991. The authors,
both former editors of Astronomy magazine, offer practical insight into astronomical equipment, finding your way around
the sky, polar alignment, using setting circles, and astrophotography. This book provides excellent explanations and is
well organized and illustrated.
All About Telescopes, Sam Brown, Edmund Scientific Company, 1975. Excellent information regarding the principles of
mount construction and operation, using setting circles, eyepiece projection, etc. Illustrations and formulas galore. Many
of the instruments pictured are outdated, however the underlying principles are timeless.
Norton’s 2000.0 Star Atlas and Reference Handbook, edited by Ian Ridpath, J. Wiley Publishers, 1989. Star maps,
information regarding polar alignment of German equatorials and observing techniques.
04-25-95

INSTALLATION OF ENCODERS AND ENCODER HOUSINGS
400 MOUNT
Parts List:
1 Right Ascension (R.A.) Encoder housing (black anodized)
1 Declination (Dec.) Encoder housing (black anodized)
1 R.A. Axis Adaptor (clear anodized, silver), labeled R.A.
1 Dec. Axis Adaptor (clear anodized, silver), labeled Dec.
To install your encoders, first remove your telescope from your mount. Remove your declination counter weight(s)
and declination counterweight shaft.
FITTING DECLINATION ENCODER HOUSING
1. If the encoders were purchased with the 400 mount, it is likely that the declination axis adapter and encoder
housing have already been installed. No further action will be required, as this encoder will remain in place.
2. If the encoders were purchased separately, the silver-colored Dec. axis adapter may be inside the black Dec. axis
encoder housing. If it is, remove it now.
3. Thread the Dec. axis adapter into the end of your Dec. axis (from where you earlier removed the Dec.
counterweight shaft). Final tightening should be done with firm hand pressure. Normally the Dec. axis adapter
will not be removed.
4. If you look into the black encoder housing, you will see the encoder itself mounted at the rear of the housing.
When this installation procedure is complete, the encoder shaft will insert into the center hole of the Dec. axis
adapter. This allows the encoder to read the motion of the declination shaft as the declination axis moves.
5. Thread the Dec. encoder housing onto the Dec. axis housing of the 400 mount. You may need to wiggle the
encoder housing gently to engage the shaft of the encoder with the hole in the center of the Dec. axis adapter.
When the threading is complete, tighten up with firm hand pressure since normally this encoder housing will not
be removed.
6. The counterweight shaft may now be rethreaded into the rear of the Dec. encoder housing.
B Declination (Dec.) encoder housing (encoder mounted inside)
D Declination axis adapter
E Declination axis housing of 400 mount
F Declination counterweight shaft
G Location to thread in encoder housing
I Encoder lead socket (phone plug input)

FITTING RIGHT ASCENSION ENCODER HOUSING
1. If the encoders were purchased with the 400 mount, it is likely that the right ascension axis adapter and encoder
housing have already been installed. Please continue to read these directions since you may need to remove
and reinstall the encoders if you use a polar alignment scope.
2. If the encoders were purchased separately, the silver-colored R.A. axis adapter may be inside the R.A. axis
encoder housing. If it is, remove it now.
3. Since the polar axis telescope and R.A. axis adapter thread into the same location, you will need to switch back
and forth between them as needed. If you use the JMI “NGC MAX” or “Mini MAX” Digital Setting Circles, you can
use the “polar align” mode in these units instead of a polar axis finder scope!
4. Thread the R.A. axis adapter into the end of your R.A. axis (If your polar alignment scope is fitted you must
remove this first.) Use moderate hand pressure to tighten the R.A. adapter since you may need to remove it to
install the polar alignment telescope at a later time.
5. If you look into the black encoder housing, you will see the encoder itself mounted at the rear of the housing.
When this installation procedure is complete, the encoder shaft will insert into the center hole of the R.A. axis
adapter. This allows the encoder to read the motion of the R.A. shaft as the right ascension axis moves.
6. Now thread the R.A. encoder housing onto the R.A. axis housing. You may need to wiggle the encoder housing
gently to engage the shaft of the encoder (located within the R.A. axis housing) with the hole in the center of the
R.A. axis adapter. Again, use moderate hand pressure as you may wish to remove this at some time.
A Right ascension (R.A.) encoder housing (encoder mounted inside)
C Right ascension axis adapter
J Right ascension axis housing
K Location to thread in encoder housing
L Encoder lead socket (phone plug input)
The hardware for your encoders is now installed. For actual set-up procedures for “Micro MAX”, “Mini MAX” or “NGC
MAX” digital readouts, refer to the relevant operating manual.
PERIODIC MAINTENANCE
If you remove the R.A. encoder frequently, you may wish to use a very tiny amount of auto grease on the mating
threads.
09-25-02