Jay
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Posts posted by Jay
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I've had similar problems with the corrupted Homeposition coordinates lately. Only 2 times so far but the latest almost made the scope to hit the pier.... not good.
I had to set the Homeposition again and now everything is working fine. The problem is of course that using automated Homing (after the photo session) is not fully reliable anymore...
Jay
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Hi Wojtek,
I have similar issues with the homefind.
Every now and then the homefind fails without any obvious reason. Especially the RA homefind used to fail almost every time when doing the procedure for the first time. After 2-3 tries it usually went through.
The trick that seem to work with my mount is starting the homefind into a "wrong direction". When the homefind slew returns and finds the reference mark, everything is fine. I'm glad that this trick works but am quite pissed that have to do this kind of things to make the mount functioning properly.
In addition the DE homefind still fails sometime. So I can't fully rely the homefind procedure working everytime, which is really frustrating because I'm operating a remote observatory.
Jay
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I am now installing a nw WIN10 PC. I checked it yesterday with simulator mode and it worked. Tonight WIN10 did a installation and today switching physically the PCs I could not get ASCOm to work.
IT took a couple of hours and the help of my son to get it working.
But now the DDM85 does not want to do what I want. e.g. homefind. It always stops.
I have tested it with a DDM85 from home in Belgium. Now Autoslew has the wrong serial code. Could that be the problem? How to change the serial code?
Regards,
Josch
Hi Josch,
I've had quite a lot of problems with my DDM60 Pro ...never found out what caused the problems but after the service everything is working quite ok, however not perfectly. E.g after switching to Win10 the first "home find" fails every-freaking-time. When turning off Autoslew and trying it again, no problems what so ever.
Changing the serial key:
http://forum.astrosysteme.com/index.php?/topic/766-new-serial-key-autoslew/
Regards,
Jay
P.S. Pointing accuracy problems might have something to do with the old sky model. I've never had problems with pointing accuracy, on the contrary, pointing has always been VERY accurate
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Hi Daniel,
Don't know if this helps any but I've had my share of problems with the Windows 10, especially with COM / USB ports when installing drivers. Sometimes installing different drivers doesn't seem to help because the "old" drivers should be have been deleted first ?
I also used to have "USB error" issues but with good cables and better USB hub, they have mostly disappeared.
After quite a lot of work I finally have everything running again (with the new laptop and Win 10), except can't still get the AAG Cloud sensor connected for some reason.
So the problem might not be with the Autoslew drivers...
Jay
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You can only adjust the time between exposures, otherwise you create a step in the tracking that breaks the image. But Autoslew does not know when you start/end your exposures...
In fact, the little drift of the PC clock has a good side effect: it creates an automatic dithering every 100 minutes!!!
Best regards.
Bernard
I usually take 20 min exposures, so a little drift every 100 minutes would mean that I have every 5th image with double dithering
Best regards,
Jay
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Hi Waldemar ...
I had been assuming the GPS receiver (whatever variety) was supposed to plug directly into one of the USB ports on my laptop .... reading your comments, just now, are you saying that it goes into one of the USB slots directly onto the DDM60 mount??? Or can it go in either?
Regards Mike
Mike,
The USB port/hub in the DDM60 mount is just a hub...and is connected to your computer via the USB cable. It doesn't matter where you put your GPS receiver...same result.
Jay
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Hi Jay,
The GPS is not a clock, it only provides time reference from time to time. Getting time from a USB GPS takes several milliseconds while the loop that controls the ASA mount has a 5 milliseconds period or less. The accuracy of the GPS time cannot be easily better that a few milliseconds when Autoslew requires less than a millisecond. So no, it is not possible to use the GPS as a real time clock with a sub-millisecond resolution. This is a fact.
In addition GPS time has some jitter effects and needs several time values from satelites to be accurate: see http://catb.org/gpsd/gpsd-time-service-howto.html
The PC real time clock is accurate. Its deviation is about 1 second per day, which is good enough for astro-photography (it means 0.2 arc second RA error after a 20 minutes exposure). Getting time from the PC clock takes less than a microsecond. But as any device, it may (very rarely) be broken.
Autoslew needs to know what time it is before a slew, in order to determine the target position, and it uses the GPS for that purpose. Once this position is reached, it needs a real time clock to stay on the target, and it uses the PC real time clock for that. They are the best available devices for these different goals.
Best regards.
Bernard
Thanks Bernard, and I agree with you that the GPS can't produce sub-millisecond time references. I was just wondering if the Autoslew only checks the time from GPS before every slew and not in between. Tracking one object without a slew can take several hours...
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Hi Lukas,
And congratulations for your new scope. It's a wonderful piece of equipment ...I know because have owned one for couple of years now
Mine is not the AT model, so there is a need to do refocusing every now and then but no complains. It's a quite fast scope and the focusing a bit critical but I've been using the "Lunatico" stepper motor, Seletek and FocusMax, and have never had problems with the focusing. The focuser itself is the original from OS. I'm using a similar combination (stepper motor, Seletek, FocusMax) with my 300 mm Canon (F 2.8) and no focusing problems there either.
Jay
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Hi Mark,
I think the end result depends very much on what kind of (and how much) flexure your setup contains...
If the system would have 0 flex (which is impossible) the unguided system would be as good as the tracking accuracy. However, there will always be more or less flexure depending what kind of setup you have. That doesn't mean that an unguided imaging setup wouldn't be able to produce wonderful results if built rigid.
Guiding with a separate guider will have similar flexure issues and they have to be dealt also before achieving good results. However, guiding with an OAG will automatically eliminate most of the flexure problems and should be able to produce good results quite easily.
Jay
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Hi all,
The GPS (nor NTP) cannot do anything in this situation as it only allows for a one shot synchronisation (say before each slew), and not for continuous time getting during the exposures.
Is this a fact or an assumption ? ...very important thing.
I only know that if the GPS signal is not found when starting Autoslew, it will try connecting to the GPS module every couple of minutes. It would be odd if that procedure would stop after finding the GPS signal once ...or only before every slew. Why would Autoslew be design in that way, especially when the time component is so critical ?
Jay
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Hi Thomas,
I'm pretty sure the GPS time is synchronized every time when starting the Autoslew. As Ian said, you'll get an error notification right away if the GPS is not working, and then it keeps checking the module every couple of minutes...
What comes to different GPS modules, I've always been using the basic GPS module without any problems ( http://usglobalsat.com/p-688-bu-353-s4.aspx#images/product/large/688.jpg).Can't comment about the accuracy because have never compared it to anything else...
Jay
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Just to let everybody know that inputting the serial key properly is VERY important...
For some reason the system will accept wrong serial keys also and e.g. last two digits have something to do with the DE axis values. I managed to input them the wrong way around and had some unstable behavior. The mount worked well most of the time so the problem was difficult to locate.
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Hi Daniel,
I do Polar alignment and pointing model only once when the season starts in September (ends in April)....if using the same scope all the time. If switching scopes then I'll do the alignment and model again.
Jay
P.S. I have a permanent observatory
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Hi Waldemar,
Yes got the mount finally back. Unfortunately they've also changed some cabling (have the DDM60 Pro model) so have to do quite a lot of extra work in my observatory to disassemble and reorganize the power input to the camera and heaters. New cables were included though..
Haven't been able to make proper tests yet but there is some worrying noise coming from the DE axis and USB cable problems (something I didn't have before). Lets hope that all this goes away after careful balancing and using the mount for a while.
Best regards,
Jay
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Thanks a lot Mark
Jay
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Can somebody remember how to install a new serial key to Autoslew after mount service ?. Have done it once but can't remember anymore.
Jay
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That they "launched" the DDM60R with ASA 2.0 and there is no info at all from the launch?
Have searched all the net of more info... nothing at all
OK, but that news has been there for a while already...
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Lukas, could you be a bit more specific. All I found was old news...
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No problem Daniel
The total length of the MLPT is the value you input to the "total exposure time" box (e.g. 120 min) And it's the same time you need/use for the shooting session for that specific target.
The number of exposures will just tell Sequence how many MLPT points (plate solves) you want Sequence to use when calculating that 120 min session MLPT curve (e.g. 6 exposures). That curve will be then sent to Autoslew.
P.S. your MLPT exposure settings are the same than plate solve settings (e.g. 5 seconds, lum filter, bin 3x3). No additional input needed.
P.P.S. your exposure setting for that session (e.g. 10 x 20 min subs) are not related to the MLPT curve other than you'd need a 200 min MLPT curve (or 220 to be safe) to perform that session using the MLPT function.
P.P.P.S Maybe it helps if you think that the MLPT is just a super accurate pointing (tracking) file created for one specific target. When the general autopointing file covers the whole sky
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Thanks, is it nessecary to use same intervall as my subs (5min) or is 15min a good estimate?
The MLPT I am reffering to is the MLPT Sequence do when it runs the Sequence, not the manual MLPT that you send to autoslew manually, the "use mlpt" in sequence is not explained (sadly)
/Daniel
Daniel, you really should read the manual one more time
You will always "send" MLPT to Autoslew. Autoslew will use it after that. Sequence is only a tool used when creating the MLPT curve. You can see when MLPT is active when the button turns orange in the Autoslew...
"Once you send the data to Autoslew the LPT button will be painted orange and Autoslew will start following the orange curve. If you want to deactivate the LPT you can click on the same button. If the button is activated the LPT will be used as long as you observe at the same hour angle you followed during the measurement. LPT is not saved, if you restart Autoslew you have to send it again from Sequence."
Sub exposure time has nothing to do with the MLPT duration/number of exposures. A good starting point is to use the 5 exposures /100 min duration (suggested by the Sequence). E.g. 300 min duration (5 h session) would need 15 exposures.
P.S. One iteration should always be enough
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Hi Max, Jay,
that's something that the developers of CCDAP/CCD Commander would have to do. Basically calling the MLPT routine right before starting the images. In ACP you can do it yourself, for CCDAP I don't know, maybe there is a way of doing it.
The alternative would be the SuperFit-Autoslew model. I tried yesterday and actually got 5 Minute unguided (and non-MLPT) round stars at 3550mm focal... No idea if it actually works over the whole sky, that's something to try.
Thanks Lukas...
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Look at the Sequence manual pages 24 - 28. Very simple thing to do...
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Good work
We need something that will eventually work with CCDAP and CCDcommander too
Max
That would be great !
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I always use the planetarium software when slewing to an object, and Autoslew (arrow keys) only sometime when framing the object if not satisfied how it has been originally positioned. The bad news is that the pointing shouldn't be that much off after only 6 days. However, I'm sure there is just some small thing you're doing differently that causes the problem.
Have you checked that the computer time is accurate and the same time is used with Autoslew and Sequence ? I'm using a GPS module and a small software in the laptop to have the time always correct.
Edit:
And have you set a new homing position after you've done any changes to the setup...e.g. polar align ?
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DDM 60 Problem Homefind position.
in ASA DDM60/PRO
Posted · Edited by Jay
Hi Wojtek and Happy New Year,
It looks like you might have a problem with plate solving. I assume you’re using Sequence ?
If the plate solve fails (e.g. pointing is too far off from the target) Autoslew cannot create a pointing file. The best way to check if plate solving is ok is to make a test plate solve (in Sequence under plate solve settings). After that test is fine, do a synch and "set new Homeposition"
Jay
P.S.... if synch fails you should not try to set a new Homeposition because it will most likely be way off.
P.P.S...and before turning off Autoslew remember to save all new settings !
P.P.P.S...GPS/Autoslew can have signal problems sometime, don't really know why. However, you can always input coordinates manually if needed.