SBIG SG-4 Operating Manual

SG-4 Autoguider

Operating Manual

SBIG Astronomical Instruments,

A Division of Diffraction Limited.

| 59 Grenfell Crescent, Unit B, Ottawa, ON Canada, k2G 0G3

Tel: [phone] | Fax: [phone]| E-mail: [e-mail] |

www.sbig.com

Not

e: This equipment has been tested and found to comply with the
limits for a Class B digital device pursuant to Part 15 of the FCC Rules.
These limits are designed to provide reasonable protection against
harmful interference in a residential installation. This equipment
generates, uses, and can radiate radio frequency energy and if not
installed and used in accordance with the instructions, may cause
harmful interference to radio communications. However, there is no
guarantee that interference will not occur in a particular installation. If
this equipment does cause harmful interference to radio or television
reception, which can be determined by turning the equipment off and
on, the user is encouraged to try to correct the interference by one or
more of the following measures:

• Reorient or relocate the receiving antenna.

• Increase the separation between

the receiver and the equipment.

• C

onnect the equipment into an outlet on a circuit different from that

to which the receiver is connected.

• Consult the dealer or an experienced radio/TV techni

cian for help

.

Shi

elded I/O cables must be used when operating this equipment. You
are also warned, that any changes to this certified device will void your
legal right to operate it.
_________________________________________________________

OPERATION Manual for SG-4 CCD Camera.
Revision 1.0 June 24, 2009
Copyright © 2009 Santa Barbara Instrument Group, Inc.

1

TABLE OF CONTENTS

I. INTRODUCTION........................................................................... 2

D

ESCRIPTION OF THE SG-4:............................................................... 2

II. INITIAL SETUP:.......................................................................... 4

S

ETUP WITH A COMPUTER:................................................................. 4

S

ETUP UNDER THE STARS: ................................................................. 7

T

RACKING: ........................................................................................ 9

R

E-PROGRAMMING THE SG-4:......................................................... 10

III. SG-4 STAND-ALONE OPERATION...................................... 11

O

VERVIEW....................................................................................... 11

S

TAND-ALONE GUIDING – STEP-BY-STEP ....................................... 11

T

ROUBLESHOOTING:........................................................................ 13

IV. THE SG-4 INTERFACE SOFTWARE ................................... 14

I

NTRODUCTION................................................................................ 14

M

ENUS ............................................................................................ 14

File Menu................................................................................... 14

Setup Menu ................................................................................ 15

W

INDOWS AND DIALOGS................................................................. 15

Main Window............................................................................. 15

Status Bar................................................................................... 17

Serial Port Setup Dialog............................................................ 18

Guiding Parameters Setup Dialog............................................. 19

SG-4 Log Dialog........................................................................ 20

V. FURTHER HELP........................................................................ 21

C

ONTACTING SBIG ......................................................................... 21

APPENDIX A: BLUETOOTH RS-232 OPERATION ................. 22

APPENDIX B: CONNECTORS ..................................................... 32

APPENDIX C: TYPICAL SPECIFICATIONS............................. 33

I. Introduction

Description of the SG-4:

SBIG’s SG-4 Stand-Alone guider is designed to be used for
guiding a CCD camera or Digital Single Lens Reflex (DSLR) Camera
at the focus of a telescope when taking a long exposure. The design
assumption was that the SG-4 would be mounted on a separate guide
telescope firmly mounted to the side of the main imaging telescope.
While it is possible to use the product successfully in other
configurations such as in an off-axis guider, it is much easier to use in
its intended configuration with a separate guide scope. The main
attribute of the SG-4 is that, once setup and focused with a PC, a
computer is not needed. This is what SBIG means by Stand-Alone
operation.

Figure One: Front View of SG-4 Stand-Alone Guider

The other important attribute of the SG-4 is it is meant to be
a true single button guider. The button turns guiding on, and turns it
off. We wanted the user to spend his or her time imaging, not
struggling with a guider. You don’t need a Ph.D. to use it!

2

Figure One shows the front view of the SG-4. The unit has a
T-thread interface on the front, and SBIG provides a 1.25 inch
nosepiece for users that do not have a T-thread coupling on their
scope. The unit is 2.8 by 4.3 by 3.5 inches (71 by 110 by 88 mm) is
size (WxHxL), and weighs about 1.0 pound (0.4 Kg). It operates
from 12 volts DC and requires 190 milliamps average current draw
(2.3 watts). As such, it can by easily operated by the portable battery
power systems popular in astronomy.

Figure Two: Connector Plate View of SG-4

Figure Two shows the connector side of the SG-4. 12 volt
power is brought in through a connector with a locking thread collar,
and an illuminated power switch is included to turn the unit on and
off. A 9 pin RS-232 connector provides for connection to a PC. At
this time SBIG only offers software for Windows based computers.
An I2C connector and External LED power are included for future
expansion capabilities. Near the bottom is a button for starting and
stopping the guiding, an LED to indicate status, and a toggle switch
to designate which side of a German Equatorial mount you are on.
Finally, there is a phone jack with ST-4 pinout connections to
interface to the mount. The relays are mechanical, so no relay box is
needed for any commercial mounts.

3

4

SBIG chose an RS-232 interface for a variety of reasons.
First of all, this device was not intended to be used with a computer at
all times like our other products – the computer was optional. So a
fast interface was not that important for normal operations like
viewing images and focusing. Secondly, our customers often have
problems with USB when trying to extend the cable beyond the
standard 15 feet. With the RS-232 link this guider can communicate
over 150 feet cable runs with no special equipment. Finally, with RS­232 the user has the option of employing a Bluetooth wireless link
and eliminating the cable altogether. Since the SG-4 is also used in
our AllSky camera having a wireless capability is very useful. With
the optional USB to RS-232 adapter SBIG offers one can
communicate at 460Kbaud over 150 feet of cable with no problem.
At this rate a full image with 16 bit accuracy can be downloaded in
15 seconds.

The SG-4 includes a shutter for automatic, remote collection
of dark frames. The CCD used is the Kodak KAI-340 interline CCD,
which has a high gain output stage allowing this device to routinely
achieve readout noise levels below 15 electrons rms. The CCD is not
cooled, but the dark current is quite low, allowing exposures longer
than 120 seconds for other applications. The maximum stand-alone
guiding exposure is 10 seconds.

II. Initial Setup:

Setup with a computer:

A computer is needed only for this initial setup. After the
setup is completed, the SG-4 can be used without connecting to a
computer unless you wish to download images or control the SG-4
remotely. A detailed description of the software is found in Section
IV. SBIG recommends becoming familiar with SG-4 operation in a
comfortable setting, someplace warm with plenty of light, before
using it at the telescope. Begin by installing the software on your PC
or laptop that will later be used to setup the camera.

• Make sure you have administrator privileges on the PC, and
insert SBIG’s software disk. A screen should pop up in a
few seconds. Select “SG-4, AllSKy-340” software to install
and, on the next screen, select “Install SG-4 Software”. The

5

software should install automatically. You might also
choose to install CCDOPS at this time. (Note – CCDOPS
will not communicate with the SG-4. It can display FITS
files saved with the SG-4 Program, but that is all.)

• Next, connect the supplied 9 pin serial cable between a serial
port on your computer and the RS-232 port on the SG-4. If
your computer does not have a serial port, one can be easily
implemented using an USB-RS-232 converter. One we have
had good luck with is the FTDI US232R-10-BLK, but there
are many to choose from. We stock this converter if you
wish to purchase it, and the drivers are also on the software
disk.

• Install the drivers from our software disk, select the “Install
USB-to-RS-232 Drivers” option under the SG-4, AllSky-340
selection.

• Finally, hook up the power to the SG-4 camera, making sure
the connector is well seated and does not wiggle. Power up
the supply, and flip the small recessed Power On/Off switch
toward the lettering. The red LED in the switch should light
steadily.

If you are using a laptop with no CD drive you must first
copy the needed files over to a thumb drive with another PC and then
load the files from the thumb drive. The files you need can be found
on the CD. Copy over the “SG-4 Software Installer” and “USB­to_RS-232 Driver Installer” folders to the Mini via the thumb drive.
Run the executable files under these folders to install the software.

In either case the software will by default be installed to the

“C:\Program Files\SBIG\SBIG SG-4 Interface Software” directory.
You can either run the SBIG SG-4.exe software from that folder, or
from the desktop shortcut that is generated automatically during the
software installation. Launch the SBIG SG-4 software. You will see
the screen shown in Figure Three.

Figure Three: SBIG SG-4.exe Opening Window

Once you have installed the software, begin setting up the
SG-4 by establishing communication with the SG-4. Do this using
the Setup menu item - Serial Port. This will open up a window you
can use to test the RS-232 link. There you can enter the COM port
and the baud rate, and hit TEST. If you are successful, a box will pop
up saying so. Note that when the Test Button is pushed, it
automatically tries to communicate with the camera on the selected
COM port, starting at 9600 baud and working it way up in speed. If it
successfully finds a camera it tells the camera to switch to a higher
baud rate and try that. If it cannot communicate at the higher baud
rate, it reverts back to the last successful baud rate. This all happens
automatically without user control. The reason you need to know this
is if you try the camera indoors on a computer with a fast link, and
then move outside to a laptop with a slower link, the camera may not
communicate. When this happens, the camera can be reset to 9600
baud by turning off the power, and holding down the Guide On/Off
button while powering up the camera, and holding it until the status
LED turns red. Then when the Serial Port command is run it will start
out at a baud rate that will work on any machine (9600).

6

7

Once you have successful communication click the “Take

Image” box and the computer will automatically initiate an exposure
of the commanded length and download it to the PC. The counts in
the image under the cursor will be automatically displayed in the bar
at the bottom of the program window when you drag the mouse over
the window, so you can check that you are sensing light by trying
exposures in the dark and such. Also, clicking the small arrow on the
left side of the screen (near the “Take Image” box) will open up a
camera control window that allows you to capture a dark, or a binned
image for focusing or experimentation. In normal operation you
don’t need the commands under this window but they are handy for
initial checkout. The binning is done on-chip. Once you are
comfortable that the camera is working properly you are ready for the
next clear night!

Setup under the stars:

Mount the SG-4 to your intended guide scope using either
the T-ring threads on the face of the SG-4, or by means of the 1.25
inch nosepiece that is provided with the camera, screwed into the T­ring threads. One should use a guide scope of at least 100 mm focal
length with the SG-4. A focal length of 200 to 400 mm is optimal,
with as fast an F/number as you can find. We estimate that 95% of
the time the SG-4 will find a guide star bright enough for a one
second guide exposure if your guide scope F/number is F/7 or faster.
A small, quality 60 to 80 mm aperture refractor is ideal. Point the
telescope at a bright star (but not the moon or a planet), start up the
SG-4 software, select a 1 second exposure, select the “Continuous”
box, and click the “Take Image” box. The software will repetitively
take images and display them. This can be slow, but start this way
your first night. You should see out-of-focus star images. Adjust
your guide scope focus until the images are only a few pixels out of
focus, which can be slow, and then click “Abort”. When the process
stops, adjust your exposure time if necessary (i.e., if the counts are
over 10,000 in the center of the star), and then select “Focus”. Focus
will take a full image, after which you click on the brightest star and
tell it to resume. It will then zoom into a small focus box that updates
more rapidly, speeding the process.

If you have a slow baud rate, you can speed up initial
focusing by opening up the camera control window and selecting 2x2
binning. This will download 4 times faster, which makes it easier to
initially find a star but is not as good for final focusing.

8

The assumption we have made here at SBIG is that you will
leave the SG-4 attached to the guide scope and do not change the
focus, or you will mark or scribe or lock down the drawtube so you
can repeat your focus position in the field without a computer, once
you have determined it.

Once you have found the best focus (it is not that critical for
guiding), make sure the phone guiding cable is connected between
your mount and the SG-4. Position an isolated bright 3

rd

to 5th
magnitude star located within 20 degrees of the celestial equator onto
the center of the SG-4 field using the “Take Image” and
“Continuous” controls, and click “Calibrate Guider”. The guider will
attempt to calibrate the mount speed. A pop-up text window will
appear so you can see the process. The SG-4 starts out with a series
of small moves with the “X” relay, which should be in the Right
Ascension direction, but by no means is necessarily in the X-direction
on the screen or on the CCD. Once it detects movement, it knows the
backlash has been taken out of the mount and it makes a few long
moves to calibrate the speed. Once it finishes in X the SG-4 will
assume the speed in the –X direction is the same, but in the opposite
direction, and it will start the same calibration process in Y. When it
finishes it will display the calibration vectors it found. It is a good
idea to check out these vectors to see if the speeds are reasonable.
Most mounts correct at a speed of around 7.5 arcseconds per second,
which is about 5 pixels per second with a focal length of 1000 mm.
With a 200 mm focal length it will be 1 pixel per second. When the
calibration finishes save your calibration text file so you can send it to
customer service at SBIG if there is a problem. The calibration you
obtain should work at any declination so, as long as you don’t rotate
your camera or the guide scope, or reposition the guide scope on your
main scope, the vectors should be good. If you have a German
Equatorial mount take note of the position of the East/West toggle
switch on the back of the SG-4 and remember to keep it in the same
place when on the same side of the pier. Do not worry about which is
East and which is West – it doesn’t matter as long as you remember
which side of the pier you were on. Note, however, that the SG-4
assumes that +X and –X correspond to RA motion for this switch to
function properly with a GEM. If you flip the telescope to the other
side, flip the switch to flip the calibration vectors. NOTE: if you
forget to flip it the mount will immediately run away in one axis
while tracking, with your corrections getting longer and longer. That
is how you will recognize this problem. Also, if calibration fails, you
will not be able to track.

9

Tracking:

To track, close the text window if it is still up from
calibration, and click “Start Autoguiding”. Another text box opens
up to show the results. The SG-4 begins by taking a series of
exposure, each time increasing the exposure time, until it finds a
guide star. When a suitable star is found it starts guiding. The mount
should begin tracking the star with a series of rapid corrections
between every exposure, if necessary. If the star is lost due to clouds
the SG-4 will start beeping, but the star has to fade a lot, by 10X or
so, before it will be lost. When you are done guiding you can click
“Abort” in the text window and the process will stop, and you can
save the results. To review these results later, or those from
calibration, use the Windows Notepad program, or Word, to open the
files.

Under SETUP you will find a Guiding Parameters choice,
which allows you to customize the tracking somewhat. The MIN
MOVE is the smallest move the SG-4 will bother sending to the
mount. Most mounts barely respond to corrections less than 0.1
second in length, so we recommend you leave this correction at 0.05
seconds. The MAX MOVE command stops the mount from making
a big move. This is useful since satellites do occasionally drift
through the track box, or you might get a radiation hit on the detector
within the track box that could also cause the mount to jump away
from the star momentarily. This setting should be set to 0.5 to 1.0
seconds.

You can also set the guiding aggressiveness.
Aggressiveness tunes the response of the SG-4 and mount to the star
position error. Lets say the star is 5 pixels off the desired position
and the correction speed is 10 pixels per second. With an
aggressiveness of 1.0 the mount would make a full move of 0.5
seconds. If the aggressiveness is 0.2 then the move would only be a
fifth as much, or 0.1 second. With a good mount with little periodic
error you should set the aggressiveness low to minimize the guider
trying to follow the star hopping around in moments of poor seeing,
say to 0.2 to 0.5. If your mount has a lot of periodic error you should
set the aggressiveness to 1.0 or the star position will lag behind its
actual position when the mount pointing is drifting. The
aggressiveness can be set to different values for X and Y. Since Y is
usually Declination, where errors occur slowly even on a mount with