unusial behaviour in EQMOD ?

[beamish]

Well my night has been cut very short.In spite of healthy weather forecasts and clear skies when setting up, the clouds expected at 4am came early . HOWEVER, having got a good polar alignment and then checked by slewing to another star (nicely in the centre of FOV),I decided to park the scope and go for EQMOD via the handset.

Having parked from viewing Alioth, I chose that as my alignment star in EQMOD but when it had finished slewing it was way off . I parked up again, disconnected and then slewed back using the h/set,- Bang on !!

Any ideas as to why this should happen? If the P/alignment was good why/what would make it go so far off, it wasn't in a strange part of the sky mind you but in a 17mm EP it wasn't in the FOV.

Karlo ( still very much an EQMOD novice)

[MikeP]

Karlo,

I think you are just asking for trouble by trying to use both EQMOD and the handset.

You have three components: the mount, EQMOD and the handset. The mount knows the position of its cogs and gearwheels and can communicate that information but it has no clue about where the OTA is pointing. Both the handset and EQMOD require a user to tell them where the OTA is pointing so that they can map the information (provided by the mount) to the sky.

I don't know if you did a 1 star align on Alioth or just slewed there with the handset but either way the handset's "understanding" of where it was pointing seemed OK. You parked and powered down, so it would remember the mapping. In between parking and trying again, the mount moved somewhere and then moved back again, so the mapping would still work.

Now, blinky (and probably all of us) have had the same problem with getting the EQMOD mapping initialised ie knowing it is pointing at the NCP and mapping that to the position of the mounts cogs. You must do absolutely everything with EQMOD/planetarium software not with the handset. Power on, slew somewhere, park, power off, manually adjust the mount to OTA up/weights down (if necessary), power on and perform the alignment routine. See blinky's threads for comments by George and Steppenwolf for variations on this "initialisation" that work for them.

Make sure that when you have the slewing with EQMOD working properly, that you always PARK and then power down. EQMOD will remember this and as long as you start from the same position, your initial alignment slews in the next session will be quite close.

I'm not suggesting you try the following but if you did the above and then powered off and powered on again, I'd bet a handset slew would be off - perhaps not to Alioth since it isn't a big slew.

You'll get it figured out Karlo but you'll have to bite the bullet and simply connect via the handset in PC mode (or whatever it is called) and then put the handset down and ignore it from then on.

Mike

[beamish]

I was under the impression that to make good use of EQMOD the mount would need to reasonably well aligned in the first place. Hence the intial alignment process. Once I was happy with that, That's when I slewed over to my 1st non-alignment star, Alioth (middle of the FOV ). Then I parked it up and powered down and put it into PC Direct and went back to the lappy opened SN and configured and connected EQMOD.

If I've read your reply correctly Mike, are you suggesting that I polar align, park and then do my alignments and adjustments entirely thru EQ ?

Please bear in mind that I haven't done this in what feels like months( well it has actually) :shock:

[MikeP]

Polar aligning is what you do to the mount. It is the physical alignment of the mount to be parallel to the axis of the earth's rotation. For observing, this only needs to be "close enough" but for long exposure imaging it needs to be as precise as possible.

The polar alignment tells EQMOD nothing (nor the handset for that matter). You have to go through the alignment process that basically tells the software what it is pointing at. EQMOD stores the RA/Dec of the object along with the data provided by the mount re its cogs at that time. The more times you repeat this step across as wide an area as possible, the more accurate the goto will be. One star is sufficient if you are then going to an object nearby but a triangle of points surrounding it is better.

Your problem at the moment is that EQMOD is a bit confused about where it is pointing to when it starts. You polar align and put the OTA into the sensible starting position of weights down and power up - it looks like all is well. Normally it will be, but initially the software will have some dubious mapping of where it is pointing, what you need to do is clear that and tell it that it is pointing at the NCP.

I found the easiest way was to tell it to PARK. When it does that, it goes to the position it thinks is where the NCP is. When you power down it saves this. If you undo the clutches and manually move the OTA so that it is pointing at the NCP ie weights down, the stored data is unaffected and the position of the cogs is unaffected but the OTA is definitely pointing in the right place. Now ehen you power on and start the alignment procedure with (say) Alioth, it should get pretty close. You centre it with the motors, tell EQMOD it is centred and EQMOD saves the known RA/Dec along with the position of the cogs and you have your 1 star mapping.

Now, as long as you PARK and then power down, you will not have to repeat the trick of fiddling with the clutches. For future observing sessions set up, polar align, power up and you'll find your goto should still be pretty good from the previous session.

HTH - if not PM me your phone number and I'll give you a call. I'm nipping out for a bit so it will be a bit later today.

Mike

[beamish]

Cheers Mike,

that was helpful. I think I got it.

I still might want a quick chat to clarify . So pm sent

[George]

Karlo,

I think you are just asking for trouble by trying to use both EQMOD and the handset.

Mike has hit the nail on the head here, EQmod was designed to work independently of the handset, Eqmod monitors the mount to work out where it is. If you make adjustments via the handset EQmod will not know this and this is what is causing you problems. You can only use one or the other

The code that was added to the handset was only done to interface EQmod, ie it only acts as a passthru.

My advice is dump the handset and get the Shoestring module http://tinyurl.com/6sxfve

Hope this clears things

[beamish]

Thanks for the replies and advice. Just had a lovely chat with Mike P (thanks again Mike) who's put me back on the right path

Started with thinking I could save a bit of time ,ended with me prattling about and losing precious clear sky-time.

Won't be happening again !!

Cheers, Karlo :withstupid: