Newbie at autoguiding, what's happening?


Roland Christen
 

In a message dated 12/13/2007 2:47:29 PM Central Standard Time,
count.zero@... writes:


When I click 'calibrate' in CCDSoft, the star moves to the right as
expected when the software does the "X+" movement. However, when it
issues "X-" the star moves downwards - so "X-" is at 90 degrees to
"X+", not 180. When "Y+" is issued the star moves up the screen, and
"Y-" moves the star to the left. So it's as if "X-" and "Y-" are
swapped round. The star returns right back to its start point, so it's
not that commands aren't being received, backlash, etc. I'm doing 15s
per movement, but I get exactly the same effect with 5s or 25s.
Unless there is something wrong with the software (which I doubt) then you
might have an incorrect connection in your camera's guider port. The AP guider
port has the correct connection for standard SBIG cameras (the connector is
directly soldered to the circuit board, so the channels can never be mixed up).
If the SBIG camera has wires connected to the guider port, then they might be
soldered on wrong, thus giving you this mixed up command sequence. If you had
the wrong guider cable wiring with the wires flipped end for end, the system
would not work at all.

Rolando


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Ben Ritchie <count.zero@...>
 

Hi folks. I'm using an AP1200GTO, AP130EDT and SBIG ST4000XCM, and i'm
having my first go at getting autoguiding. I have the CCD aligned so
that the star correctly moves left/right and up/down when I use the
hand controller (i.e. the CCD is aligned with the axes of the mount),
and it's connected to the mount's autoguider port with the
SBIG-supplied cable.

When I click 'calibrate' in CCDSoft, the star moves to the right as
expected when the software does the "X+" movement. However, when it
issues "X-" the star moves downwards - so "X-" is at 90 degrees to
"X+", not 180. When "Y+" is issued the star moves up the screen, and
"Y-" moves the star to the left. So it's as if "X-" and "Y-" are
swapped round. The star returns right back to its start point, so it's
not that commands aren't being received, backlash, etc. I'm doing 15s
per movement, but I get exactly the same effect with 5s or 25s.

I've tried with a spare SBIG relay cable, but that gives the same
result. I suspect it's a newbie error somewhere, but I can't find any
sign of a relevant option. I don't even know if i'm missing a mount
option or CCD/software one.

Any suggestions appreciated!

Ben.


Ben Ritchie <count.zero@...>
 

--- In ap-gto@..., chris1011@... wrote:


Unless there is something wrong with the software (which I doubt)
then you
might have an incorrect connection in your camera's guider port. The
AP guider
port has the correct connection for standard SBIG cameras (the
connector is
directly soldered to the circuit board, so the channels can never be
mixed up).
If the SBIG camera has wires connected to the guider port, then they
might be
soldered on wrong, thus giving you this mixed up command sequence.
If you had
the wrong guider cable wiring with the wires flipped end for end,
the system
would not work at all.

Rolando

Thanks Roland. I get the same effect in CCDOps and CCDSoft, so I don't
think it's the software. We clouded over pretty quickly last night so
I didn't get more time to troubleshoot, but I have a ST-402ME too that
I can use - I think if that calibrates correctly then it's pointing to
a problem with the ST-4000XCM.

Ben.


ayiomamitis
 

--- In ap-gto@..., "Ben Ritchie" <count.zero@...> wrote:

--- In ap-gto@..., chris1011@ wrote:


Unless there is something wrong with the software (which I doubt)
then you
might have an incorrect connection in your camera's guider port. The
AP guider
port has the correct connection for standard SBIG cameras (the
connector is
directly soldered to the circuit board, so the channels can never be
mixed up).
If the SBIG camera has wires connected to the guider port, then they
might be
soldered on wrong, thus giving you this mixed up command sequence.
If you had
the wrong guider cable wiring with the wires flipped end for end,
the system
would not work at all.

Rolando

Thanks Roland. I get the same effect in CCDOps and CCDSoft, so I don't
think it's the software. We clouded over pretty quickly last night so
I didn't get more time to troubleshoot, but I have a ST-402ME too that
I can use - I think if that calibrates correctly then it's pointing to
a problem with the ST-4000XCM.
I am also a dedicated CCDSoft user and I have NEVER seen such
behaviour. I am almost convinced it is the camera.

As an aside, a better means to assess how parallel the camera is with
the axes of the mount is to look at the calibration result tab which
gives a very nice graphic of the +X, -X, +Y and -Y movements and the
associated calibrated results/values for each second of pulse.

Also, something which I never have been able to get to work within
CCDSoft is the maximum correction that the autoguider is allowed to make.

Anthony.


Ben.


Ben Ritchie <count.zero@...>
 

--- In ap-gto@..., "ayiomamitis" <ayiomami@...> wrote:
I am also a dedicated CCDSoft user and I have NEVER seen such
behaviour. I am almost convinced it is the camera.

As an aside, a better means to assess how parallel the camera is with
the axes of the mount is to look at the calibration result tab which
gives a very nice graphic of the +X, -X, +Y and -Y movements and the
associated calibrated results/values for each second of pulse.
Hi Anthony

The calibration graphic is clearly wrong. Sadly I can't attach a
screen grab on these forums (I think?) but the values I get (pixels/s
and angle) are

X+ 9.2436 1.8809
X- 6.8117 91.0365
Y+ 6.8739 271.3662
Y- 9.2714 181.4919

so X+ and Y- are pretty much perfectly matched, as are X- and Y+. The
graph looks almost perfect ... until you realise that the labels are
wrong.

I *think* it should be fixable by modifying the ST7-RC adapter to swap
X- and Y- (in fact, the adapter may be the cause of the problem).

Sorry, i'll stop cluttering up the list with SBIG-speak!

Ben.


ayiomamitis
 

--- In ap-gto@..., "Ben Ritchie" <count.zero@...> wrote:

--- In ap-gto@..., "ayiomamitis" <ayiomami@> wrote:
I am also a dedicated CCDSoft user and I have NEVER seen such
behaviour. I am almost convinced it is the camera.

As an aside, a better means to assess how parallel the camera is with
the axes of the mount is to look at the calibration result tab which
gives a very nice graphic of the +X, -X, +Y and -Y movements and the
associated calibrated results/values for each second of pulse.
Hi Anthony
Hi Ben,


The calibration graphic is clearly wrong.
My comment in relation to the graphic was in response to your comment
that you use the slews with the hand controller to see how close you
are to having the two sets of axes (camera and mount) parallel. A
really neat way is to look at the graphic following a calibration and
which will show you precisely how well they match.

Sadly I can't attach a
screen grab on these forums (I think?) but the values I get (pixels/s
and angle) are

X+ 9.2436 1.8809
X- 6.8117 91.0365
Y+ 6.8739 271.3662
Y- 9.2714 181.4919
The good thing about these numbers is that they show a very good
calibration (ignoring the problem of the mixed up X+/Y- and X-/Y+).

so X+ and Y- are pretty much perfectly matched, as are X- and Y+. The
graph looks almost perfect ... until you realise that the labels are
wrong.
Yes, I agree.


I *think* it should be fixable by modifying the ST7-RC adapter to swap
X- and Y- (in fact, the adapter may be the cause of the problem).
Yes, good point. I forgot about the ST7-RC adapter.


Sorry, i'll stop cluttering up the list with SBIG-speak!
No problem with me since we all use one of the two to three programs
out there for image acquisition. Also, seeing such problems is
educational for all of us. Case in point is your experience right now
and which is something I have never encountered personally or in any
of the groups I follow.

Anthony.


Ben.


Ben Ritchie <count.zero@...>
 


I *think* it should be fixable by modifying the ST7-RC adapter to swap
X- and Y- (in fact, the adapter may be the cause of the problem).
Yes, good point. I forgot about the ST7-RC adapter.


Sorry, i'll stop cluttering up the list with SBIG-speak!
No problem with me since we all use one of the two to three programs
out there for image acquisition. Also, seeing such problems is
educational for all of us. Case in point is your experience right now
and which is something I have never encountered personally or in any
of the groups I follow.

Anthony.
I've just taken the ST7-RC to pieces (hope I can get it back together
again ;) and i'm fairly sure X+ and Y+ are swapped in the adapter.
Looking at SBIG's wiring diagram, pin 3 of the 9-pin plug (X+) is
connected to pin 2 of the RJ11 socket (Y+), so when the camera issues
an X+ slew it's going to go to Y+ on the mount - and vice versa (pin 4
-> pin 1). I'll check with SBIG before rewiring it, but I think that's
it. Chalk up another one to the list of "weird things that can go
wrong while imaging".

At least it's the cheapest bit to replace ;)

Ben.

P.S. in an attempt to keep this slightly on-topic, i'd just like to
say that my 1200GTO is undoubtedly the best Astronomy purchase I ever
made. It's just an absolute pleasure to use... :)


ayiomamitis
 

--- In ap-gto@..., "Ben Ritchie" <count.zero@...> wrote:

P.S. in an attempt to keep this slightly on-topic, i'd just like to
say that my 1200GTO is undoubtedly the best Astronomy purchase I ever
made. It's just an absolute pleasure to use... :)
Ben,

I am so impressed with my AP1200GTO, I will be looking to pick up
another one during 2008. In fact, I have a little dilemma ... one
AP3600 or two AP1200???? I suspect the latter so as to have multiple
scopes imaging at each opportunity. YES!!!

Anthony.