A question about teaching PEC on a Sky Watcher EQ6. Is it possible to teach the mount PEC using the SSAG and PHD Guiding? I realize the guide commands are going to the guide port. The guide port should be in parallel to the controller keys? Do the keys on the hand controller have to be pressed to actually record the PEC commands? Seems to me that the SSAG is doing the same thing I would be doing using a reticle EP. It would be more accurate than my eye as it controls within a couple of pixels.

If I am guiding with PHD do I even have to worry about PEC. I have taken 10 min exposures using PHD and the stars are perfectly round without PEC. It seems that PEC is moot if you are auto guiding. If I used PEC then the guide cam would just be adjusting less is all. Is this correct reasoning?

The EQ6 has no encoders so it has no encoder home position to reference to PEC so what would be the point? You would seeming have to teach PEC after every power down. 

Thanks for any input.

JJ 

The basic problem with training PEC using a guidecam and guide scope is that your results may be less consistent than if you used the main scope (assuming the FL of your imaging scope is a good deal longer than that of your guide scope.

And you might have some flexure to contend with.

johnjohnson:

... If I used PEC then the guide cam would just be adjusting less is all. Is this correct reasoning?

Yes, but it can still be helpful. For example, what happens if you are making an RGB series and you lose a guide star at some point? If your subexposures are longer than your mount can track without PEC, then at least one of them is going to be kaput due to guide-star loss if you haven't trained for PEC. On the other hand, if your tracking with PEC is good enough for a period longer than your subexposure, then you might survive guide-star loss on one or more of a series of subs.

The EQ6 has no encoders so it has no encoder home position to reference to PEC so what would be the point? You would seeming have to teach PEC after every power down. 

Yep. I have that problem with my non-GoTo CI-700. There are parts of the gearing where 2 minutes is smooth, but no more, without PEC. With PEC it goes up to 6 minutes if my focal length is shorter than 1,000mm. With guiding, it's considerably better than that but I haven't guided it in several years (I'm now using a 3RF mount most of the time, an AP900).

I'm a fanatic about PEC when I'm doing double-star observing. I frequently do that at insane magnifications (above 600X) and doing the measurements using an astrometric eyepiece means I'm rotating the eyepiece 180 degrees every half-minute or so for 5 to 10 minutes at a time. You do this for a given star twice a night (equidistant from the meridian on both sides of the meridian) and 10 or 12 stars in a night, and you really appreciate tip-top tracking!

This is the only astronomy "exercise" I can think of that's anywhere near as tedious as manual guiding ... and not many of us do it anymore (not hard to see why!).

 Thanks Chip,

I had not taken the guide scope flexure into consideration. I feel I have a fairly rigid set up but it would add one more variable to the mix. The periodic interval for the EQ6 is 8 minutes so I guess its worth the time, and 8 minutes isn't so bad. I do wish the mount was a closed loop system so it would only have to be taught once. You get what you pay for I guess. Money saved = 8 min per AP session LOL. I was just looking to get around it the easy way.

Again thanks!

JJ
 

I used to "train" the PEC on my CGE and MI mounts using the manufacturer's software, but I gave CCDware's PemPro a try, and haven't looked back since. It is well worth the few dollars it cost. Take a look at their website at:

www.ccdware.com/products/pempro

It will allow some improvement over the standard multi-cycle averaging that is the norm for the manufacturer's software/firmware. They claim to support both Orion and Skywatcher EQ6 mounts.

Robert

Robert,

This is great and what I was looking for. I use the Orion Star Shoot Auto Guider. It plugs directly into the mount for AG. How do you connect to your mount? I guess the better question is how do you AG. I

JJ 

johnjohnson:

It plugs directly into the mount for AG

I do it the same way you're doing it. The AG port is the "only" way to go for guiding. The old style "LX200" instruction set going through the HC offers a less refined control of the mount for guiding.

As far as setting up the PEC, I use PEMPro to collect multiple cycles (through the main scope, with the imaging camera), go through their Fourier analysis, then generate a PEC curve and let their SW upload it directly to my mount's PROM. The CGE can use PECTools as an intermediary, the MI takes the curve directly from PemPro.

Robert

Robert,

I would have to use the SSAG in the main scope to generate the data as I use a DSLR as my imager. I do not think my HC is capable of just accepting the PEC data only. I will have to look into that some more. It is the way older version 2.04 of the synscan controller.

JJ