GTD E.fric Manuel utilisateur
E.fric Precision Friction Drive German Equatorial Mount
User Manual
WARNINGS
For the technical details and specifications of the product please consult the
Tech Sheet. This document explains the correct use of the E.fric to get the most out of
your purchase. For a guide to using the nStep controller read this.
Setup
Use a sturdy tripod/pier specified
at least for 80 kg load.
The tripod or pier should be
approximately levelled to avoid
cross interference between
azimuth and elevation when
polar alignment is done.
The azimuth pin should be at
least d10mm diameter and at a
radius of approximately 60 mm.
See the Tech sheet for more info!
GTD E.fric manual 1 ctober 2021
Potential finger trap: do not insert your finger into the elevation base while adjusting elevation! It
may injure your finger.
Hazard to the drive electronics: do not rotate manually the axes of the mount with locked
clutches and connected electronics! The motors can emit high energy pulses that damage the
electronics.
Azimuth pin to North
3pc hard plastic
pads
Central lock
M10 or M12
Legs should rest
n a firm surface
Do not use pier extensions like this. This is correct.
Operating the E.fric
Connect the electronics (one of many optional choices) with your motor cable
(supplied on request). The supply voltage to the electronics should N T be under
12V
GTD E.fric manual 2 ctober 2021
RA axis lock
(clckwise closed)
DEC axis lock
(clockwise closed)
RA Motor
connector
DEC motor
connector
Most tripods/piers resist compression well but fail for torsion. Insert two pins/bolts
into holes on the top plate and rotate it slightly with a steel bar to see how it resists!
Wind forces generate torsion, for this reason torsional stiffness is fundamental.
Insert and lock the counterweight shaft as shown above! It rotates with the DEC axis
The E.fric has a mechanical limit of RA rotation about an hour before the meridian
when the TA is on the EAST side of the pier. This does not limit automated
operation since this part of the sky is reached with the TA on the WEST side of the
pier.
Balancing
Mount the TA with the sky end corresponding to the "SKY"
sign on the losmandy
platform.
This will ensure that the
locking knobs do not interfere
with the mount body.
You can replace the long
knobs with M6x40 cylindrical
head bolts.
GTD E.fric manual 3 ctober 2021
Sky end mark
If there is some asymmetric accessory on your TA, it will cause imbalance in some
positions (not all). The top and bottom of the TA are symmetric positions, any side
mounted accessory should be balanced.
GTD E.fric manual 4 ctober 2021
Losmandy knobs
on left
Tubering knobs
on right
Focuser knob
n top/bottom
You see some tips for fine tuning the balance above.
Polar alignment
With a tool like the program “Sharpcap” 10 arcsecond precision is achievable.
Multiple star sky models can correct goto and tracking but field rotation not. For this
reason good polar alignment is essential for astrophotography.
Do not remove or add accessories after polar alignment because it will hamper
precision.
Keep the central locking tight while adjusting. The mount will be able to rotate
smoothly on the hard plastic pads.
Below is the result of the polar alignment process with Sharpcap
GTD E.fric manual 5 ctober 2021
Azimuth
control
Elevation control
Final adjustmet
UP
Loose for adjustment
Lock gently after
Adjustment
(check azimuth)
Central lock
tightened
Instructions
here
Improving flip precision (optional)
The largest source of pointing error when the moun is making a meridian flip is
optical axis/dec axis orthogonality error. Use trimming grub-screws (or shims)
between the Losmandy rail and one of the tube rings.
GTD E.fric manual 6 ctober 2021
To improve the precision, centre a (bright) star (CCD, electronic crosshair) on either
side of the meridian, preferably not far from the meridian. Now make the mount flip
by slewing the mount to a (bright) star on the other side of the meridian (not far).
Now correct HALF the flip error in RA with the trimming screws.
Unguided imaging
Here are some tips to get the best result of unguided imaging.
The setup must be stable (no soft soil).
The TA should be balanced accurately in all positions.
Must have a precise polar alignment (around 10") or multi star model (will have field
rotation near the pole).
Keep flexure at a minimum! Pay attention to:lock focuser, extension rings, set
screws.
Remember that any part of your TA that is not PERFECTLY firm will flex easily.
Do not leave cables hanging off the TA/CCD.
Apply dual axis refraction corrected tracking (preferably with atmospheric
parameters sensor for nstep). Refraction can introduce arcsecond level errors in a
few minutes.
Generally speaking, refractors are much more suitable for unguided imaging due to
small TA flexure.
Tracking speed (in nstep controller) can be fine tuned if needed. Do this near the
meridian where refraction has little effect on apparent sidereal speed.
GTD E.fric manual 7 ctober 2021
ne of 2 adjusting
grub-screws
Losmandy rail
Guided Imaging
When autoguiding a mount, the guide star's position will change for three main
reasons.
The first is the tracking error of the mount,
the second is fluctuations in seeing,
the third is mechanical flexture in general and refraction effects.
With E.fric, the first error is negligible, you have the other two only. If you stick with
your habit of using short guide intervals (less than 4-5 sec) your RMS will be no
better than with any other mount and it will be seeing dependent. If you want to take
full benefit of the precision that your E.fric offers, keep the guide exposure above 5
sec in all cases. The worst the seeing is, the longer guide exposures will help.
Below is an example under good seeing, 4 sec guide exposure.
GTD E.fric manual 8 ctober 2021
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