Telescope command 1x >

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Jean-Francois
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Location: Germany

Telescope command 1x >

#1

Post by Jean-Francois »

Hello Robin,

Since several releases (v4 included), the telescope command in the "->" direction with 1x rate is not more working.
The other direction or with other rates are working, but not the 1x > direction.

It is helpful to have the slow telescope movement for centering and synchronisation (during polar alignment).

I use the SynScan software. I do not change the telescope or update the telescope driver.
I do not remember which version was the last working, but the telescope is no more moving in "1x >" with the last 3.2 and 4 versions.


Regards,
Jean-Francois
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Re: Telescope command 1x >

#2

Post by admin »

Hi Jean-Francois,

I'm not sure if this is something I can fix – different Ascom mounts have different behaviour when you ask them to move at 1x sidereal in the +RA direction while tracking. Some (like EQMOD) and the 1x requested rate to the tracking rate and therefore move the mount. Others like the ASCOM Simulator interpret the 1x request as being a request to move at the tracking rate, so the mount stays still. There's no way to tell which approach a particular mount is going to take, so if I fix things for one category I end up breaking things the other :(

I think the best I can do is add an option for 2x rate if available - in some cases that will only move at 1x relative to tracking in the +RA direction, but at least it should work.

Cheers, Robin
Jean-Francois
Posts: 361
Joined: Sun Oct 13, 2019 10:52 am
Location: Germany

Re: Telescope command 1x >

#3

Post by Jean-Francois »

Hello Robin,

In the past (20th February) I do with 2 computers and with 2 telescopes and 2 cameras the Chaldaea asteroid occultation.
I use SharpCap on both computer, and It was not a problem to center/move the star with the 1x > or < button.
I notice the change some days later. I do not modify the telescope.

The question is more why/what is changed ?

Regards,
Jean-Francois
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Re: Telescope command 1x >

#4

Post by admin »

Hi Jean François,

Well, I couldn't find anything in the recent changes in SharpCap that would seem to be related to this issue, which made it very odd.

If you can find two versions of SharpCap where one works and a later one doesn't then I have more chance of digging into the code to find out what changed between those versions.

Cheers, Robin
Jean-Francois
Posts: 361
Joined: Sun Oct 13, 2019 10:52 am
Location: Germany

Re: Telescope command 1x >

#5

Post by Jean-Francois »

Hello Robin,

I de-install the last 3.2 version and I install the 6480 ... same behavior.
I de-install the 6480 version and I install the 6477 ... same behavior.
I de-install the 6477 version and I install the 6473 ... same behavior.
I de-install the 6473 version and I install the 6452 ... same behavior.

So .. I'm now no more sure that I use the 1x > button in the past.

What I'm sure, is that I use SharpCap for precise 2-Star alignment followed by a Polar-Alignment with the hand controller.
It could be that I move each time the telescope only with the hand controller or with the SynScan button.

OK, I do more tests ...

I connect my EQ8 mount, I start the SynScan App and connect with the EQ8. I start 3 programs ... Prism, CdC and SharpCap (in addition of SynScan).
All the program can control the telescope. It is possible to see the telescope displacement on the Prism and CdC star chart when another software commands the movement.

I use the SynScan 1x < and > buttons ... both move the telescope.
I use the Prism 1x < and > buttons ... both move the telescope.
I use the CdC 1x < and > buttons ... both move the telescope.

And now SharpCap ...
with tracking activated: < moves the star with 2x star rate and > has no movement
with no tracking: the star drifts continuously, with < it stops the star displacement and > moves the star 2x the star rate

I guess that "something" is in SharpCap (3 other softwares move the star as wanted).
Maybe you follow the ASCOM rules exactly and the other not, but the other software perform the 1x movement as wanted.

I do not test with other driver ... EQMOD for example. I can test it next time.

Regards,
Jean-Francois
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Re: Telescope command 1x >

#6

Post by admin »

Hi,

Ok, it looks like the only robust way to move in the -RA direction at 1x speed is to turn the tracking off temporarily and let the planet do the work :) What SharpCap was doing before was offsetting the rate by 1x to account for the tracking, which works with EQMOD but not with the ASCOM simulator and not with Synscan either by the sound of it.

I will make the change and we will see if it holds up for all mounts.

cheers,

Robin
Jean-Francois
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Re: Telescope command 1x >

#7

Post by Jean-Francois »

Hello Robin,

OK. I will test it again as soon as you have an update (but it is necessary that the 1x continues to work with all other mounts).

Regards,
Jean-Francois
Jean-Francois
Posts: 361
Joined: Sun Oct 13, 2019 10:52 am
Location: Germany

Re: Telescope command 1x >

#8

Post by Jean-Francois »

Hello Robin,

The telescope movement "problem" is still not solved ... and I found more questions.

I wish to command the mount in all direction and since last week, I wish to slew in both direction at the same time and repeatedly forward and backward.

I start with the crazy idea to scan the sun surface (for the SHG/spectrometer observation) no more in pure RA or DEC, but now in a rotated X/Y system.
It is possible to detect the rotation of the sun with de Doppler effect on the spectral lines.
The axis of the sun change the orientation relative to the RA/DEC axis ... so my idea is to perform the scan of the spectrometer slit all the time with the slit parallel to the sun rotation axis.

Other point ... my capture script in SharpCap can take several scans automatically. I works perfectly in DEC ... DEC+ is exact the DEC-.
But not in RA ... depending on the driver I used with my EQ8 mount, I have different results (see the PDF for SynScan 1.19.20, 2.3.8 and GSS 1.6.1).
I tested yesterday evening the new SynScan 2.3.9 ... and surprise! some of the rate seems to be now different.
RA_scan_test_GSS_SynScan_simulator.pdf
(797.96 KiB) Downloaded 34 times

So ... What I wish to know is ... can you confirm that SharpCap perform no change/offset before sending the MoveAxis parameter to the ASCOM driver ?

And other point I do not know. I searched, but I did not find. I found only the telescope driver name. I search in addition the telescope driver information (version number for example). Why ... simple I found that the SynScan drivers have some different behaviour and it could be change in the future.

Regards,
Jean-Francois
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Re: Telescope command 1x >

#9

Post by admin »

Hi Jean-Francois,

just checking through the code I can see that SharpCap does manipulate the movement rate in RA under the following situations

* Mount is tracking
* Movement rate is less than 16 times sidereal
* Mount has ranges of available movement rates rather than fixed rates

In this case, SharpCap adds an offset of 1x sidereal to the movement rate to try to get the rate to be relative to sidereal. In the case that adding the offset gives a result of zero, SharpCap stops tracking to get a movement rate of -1 * sidereal relative to the normal tracking rate. Unfortunately I suspect that this is one of the places where the ASCOM standard is ill-defined (or at least the implementations are very variable in relation to how a movement rate is treated relative to a tracking mount).

You can, if you wish, talk direct to the ASCOM driver for the mount and bypass this manipulation - use the object

Code: Select all

SharpCap.Mounts.SelectedMount.AscomMount
This will also let you get at the extra properties like the description, driver version, etc.

cheers,

Robin
Jean-Francois
Posts: 361
Joined: Sun Oct 13, 2019 10:52 am
Location: Germany

Re: Telescope command 1x >

#10

Post by Jean-Francois »

Hello Robin,

In German, we say ... "Oh!, je, oh!, je" and some people add "alte Schwede".
So THAT EXPLAIN the 16x rate behaviour :-)
... And I do not need to complain to SkyWatcher. I have already messages with Robert from the GSS driver.

Thanks for the command, I tried it, but I think that I tried it without the mount connected.
I remark now that the ASCOM driver is different as the SynScan App version number.
For SkyWatcher, the actual driver is the 1.3.1, here it is the 1.3.0 because I did not yet update it on my desktop computer.
My test from yesterday was with the last version SynScan 2.3.9 and ASCOM driver 1.3.1.
I remark that the movement between 1x and 4x are now OK.


Here what I saw without the mount connected and after the connection:
SharpCap_mount_info.jpg
SharpCap_mount_info.jpg (178.31 KiB) Viewed 390 times

OK ... SharpCap does something before sending the command to the ASCOM driver. Please do not change it.
Or if you want to change it, please do it as soon as possible :-)

Why ? ... the normal scan for the sun observation with the SHG is done around 16x ... so typically between 4x and 32x.

Regards,
Jean-Francois
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