Is it possible to use the PEC in my iOptron CEM26 along with the guider in Ekos, or PHD2 and it's PEC capability? I see conflicting info on whether it can or not.

Thanks.

I don't have an iOptron mount, but rather a Sky-Watcher (EQ6-R Pro), that I use with the mount's built-in PEC. I trained it on Windows using PEMPro. I think I saw somewhere that some models of iOptron mounts don't allow guiding and PEC at the same time (which is incredibly stupid if that is the case). But if that isn't the case with your mount, then there would be no other reason why you couldn't use it with Ekos and PHD2.

BTW, the new internal guider in Ekos has the same Predictive PEC ability that PHD2 has, so that's one more reason to use Ekos guiding instead of PHD2. And yes, you can use PHD2's (and Ekos) predictive PEC in addition to the mount's built-in PEC. They complement each other. They even say so on the PHD2 website in the documentation for the Predictive PEC algorithm.

Thanks for your reply.

Well looking around online it appears I should NOT use the mount's PEC along with a guider. However in the Ekos guider I don't see the same settings options I see for PHD2. You mention the predictive PEC option, but I don't see where to set that. Also is there a guiding Assistant as there is in PHD2? There appears to be a lot of control parameters missing in the Ekos guider that's present in PHD2. Looking in the Ekos options, I see an option for an RA only set of controls called GPG RA Guider, although it's not clear to me what that is. I also see and option for DEC backlash in guide calibration, but how do you perform guide calibration, or is that something that just happens when I press the main GUIDE button?

I would rather not use PHD2 in Ekos, but I feel I need to run the Guiding Assistant for my mount, as my first forays with this new mount have given me insane plots, as you can see below. So I'm trying to get a handle as to what's causing these things, if they are internal to the mount, incorrect software settings, or if there are external variables causing this.

Thanks again for your reply.

 

 

Sorry I wasn't more clear in my response. In Ekos, the GPG RA guider is the same as Predictive PEC in PHD2. And no, Ekos does not have anything like PHD2's Guiding Assistant, unfortunately.

Wow, that's one ugly looking graph. I would actually start by disabling guiding output, and just let it graph the tracking error with no guiding commands being sent, just to see what the mount is doing all on its own. That will tell you if those large spikes are a result of something mechanical in the mount, or the guider going crazy.

Thanks again.

Yeah, that's pretty frightening, that graph.

So Ekos can make a guide log even if the guider is off? Just start shooting something? Or just set Tracking Enabled in the mount controller?

Thanks again.

Phil:  You asked several questions:

Re missing parameters: I assume you mean at least aggressiveness and min/max move for RA and DEC. In the version of KStars that you're using, those parameters can b found by looking on the main guider page, there are some tabs on the right side of the page and one is called control, click that. In version 3.5.5 that tab was moved to the same menu that you were looking at.

Re making a plot of mount movement without any guiding: the way to do that in Ekos is to "guide" but disable the guide pulses for both RA and DEC. That's on the main guiding page--the line on the left that says "Directions"--just uncheck both RA and DEC. Remember to re-check them when you're done.

To force a calibration: you can click on the garbage can to the right of the guide button which will clear the calibration. Then, after you press Guide it should calibrate before guiding. Depending on your settings, Ekos may try and reuse calibrations, or it may re-calibrate after each mount slew, so this garbage can press might not be needed. 

Thanks for your reply. I'll try these out and see if it can show me if my issues are hardware related. I just got this CEM26, and so far only had 3 outings with it, and the plots have been like this. Although the mount was on concrete, itself on bedrock, there was significant traffic nearby, and I'm wondering if that was an external contributor. I will set the mount up somewhere more isolated for further tests, and I'll turn these functions off and on and see what kind of results I get.
Thanks again.

...also, when temporarily disabling RA and DEC, do I need to disable the buttons underneath, or does that not matter?
Thanks.

 

I believe that if RA/DEC is not enabled, then the direction buttons below don't matter.
Hy

That's correct.  Unlike many other mount brands, iOptron PEC handling fiercely fights with mount guide inputs.   I've tried it a dozen times on three different mounts with the internal guider and PHD2 and the result was clear each time: if you're guiding an iOptron mount, do not use mount-based PEC.  My results were always noticeably worse, and often were disastrous.  

The thing is, none of my iOptron mounts have anything but smooth PE... and smooth PE is easy to guide out. 

Predictive PEC in PHD2 or GPG RA Guiding in KStars work great, though.  Just find the worm period of your mount and specify it in the software vs letting the software "guess" at your worm period.

Thanks for that info. On my CEM26, the worm period is listed at 600 seconds. Strangely, that data was only listed online and not in my CEM26 manual. However another strange spec listed is "Permanent PEC". I'm not sure what this means or if I have to be concerned about it. I just hope the mount isn't going it's own way with PEC all the time. The hand controller only lists 3 options for PEC, Record, Playback, and Data Integrity. I have not used this function, and I'm going to assume that "Playback" means activating PEC in the mount. Seems a rather clumsy approach to this.

So I'm just going to assume there is no active PEC going on in the mount and I'll enter 600 seconds in the GPG RA Guider Major Period box and deactivate the Estimate Period checkbox, correct?

Thanks again.
 
 

Permanent means that the correction curve is stored in the mount and you can use it without PC connected. For this to work, you need to record this curve into the mount. This can be done manually doing corrections while looking into eyepiece (old fashioned way), or you can let a software, like PHD2, do the corrections while the mount is recording them. Once there is a curve recorded in the mount, you can enable the PPEC (PEC playback in the menu). But there is one major problem: while a mount is playing a PEC curve back, the guiding pulses will be mostly canceled by the corrections done by mount's internal electronics. In this case the guiding pulses are fighting against corrections done by the mount.
The best way how to use PEC is with GPG RA algorithm, as it was said earlier. The PEC curve will not be stored in the mount or in the Ekos, it will be freshly recorded once the algorithm is used.