Are there any PMX PE measurements yet?

[gregbradley]

Has anyone taken their PMX for a test run yet and measured the PE?

Is it smooth? Any spikes? I got an email from someone complaining their PMX worm was no good and it gave a couple of nasty spikes and it took a while to get SB to agree to replace it. It would bump the autoguider off.

Hopefully its just teething problems with their production line. I hope they are not in such a mad rush to fill orders a few quality issues are overlooked.

A bit worrying.

Greg.

[nickbtx]

Hi Greg,
I've measured the PE on mine at 5.6 arc seconds, uncorrected. I've tried it a couple of times and have gotten different results (5.6 being the lowest). I suspect the seeing may have had something to do with that.
Nick

[gregbradley]

Yes the seeing would definitely affect the measurement. That sounds pretty good.

Greg.

[Ross G]

Hi Nick,

Is that measurement peak to peak or +-.

Thanks.

Ross.

[Paul Haese]

Just one thing for those unfamiliar. Make your exposures around 0.11 and get it to watch the star for 25 minutes as a minimum. You will get a good reading then.

[cventer]

Have not done pe yet, but was polar aligning last night. Afterwards did a 2 min test exposure at 1400mm fl. I watched the guide relays in tcs and they lit up twice for a few ms in the whole exposure. Had lovely round stars afterwards. No PEC . Me happy so far.

[frolinmod]

25 minutes is a long time to go with no guiding and ProTrack disabled unless your polar alignment is very good indeed. A great big R Lee Ermey "Hoorah!" to you if your polar alignment is that good. In my case, in order to go that long in CCDsoft I had to increase the tracking box size or whatever it's called so that the star didn't slowly drift all the way outside the box.

[gregbradley]

I was able to get 20 minutes and could've gone 25 minutes but as you say that was only after several iterations of improving my polar alignment and making sure balance was spot on.

By the way how do you increase the size of the tracking box in CCDsoft?
That could be handy at times.


Greg.

[Paul Haese]

If you get you PA right Ernie you will find you can go that long. Tom from SB said this is what you should do to get PE sorted. I use Precision PEC and CCDsoft for that job. I want to do another run soon, when I have time. Will need to do it for the 12" refinement. Only done PEC for the TSA so far. The parameters are a lot wider given the focal length.

[cventer]

Greg and others, with regard to balance what are you doing to weight east side once you have balanced ? Do you use a movable weight or do you adjust the counterweight on the shaft.

[Paul Haese]

If the MX is anything like the PME. Then you will find that balance must be perfect as written in the manual. Balance cannot be biased.

[gregbradley]

I balance the mount with the scope horizontal in both axes.
I check it isn't wildly different at the usual imaging angle. With a scope mounted on top that will be different to horizontal so I check at the usual imaging angle and adjust to that rather than to horizontal.

As far sensitivity to balance I find my PME very tolerant. It has been at times somewhat out of balance but I still got round stars. The beauty of a heavy duty mount.

But for PEC etc you don't want any other factor in the way. I don't have a shifting weight balance. I know a lot of mounts say to weight the west side slightly so the gears are always meshed. I am not sure if that is true with the PME as it is belt driven but perhaps it is.

PMX - it may be different, its not as beefy as a PME so weight balance may be more important but I suspect its not as critical as with other mounts.

Greg.

[frolinmod]

With the ME, imbalance definitely causes increased power usage and drains your batteries faster in the field. I have measured this using the device linked to below.

I'll lay odds that the MX is similar in this regard.

Put one of these on your battery (or power supply) and you can measure and graph the power usage with excel:

http://www.powerwerx.com/digital-meters/pwrcheck-dc-power-analyzer-watt-meter-logging-software-usb.html

[rat156]

You need clear skies to do this don't you:mad2:

Cheers
Stuart

[nickbtx]

Ross,
That was peak to peak.

[frolinmod]

Oh, I increased the tracking box by following this article:

http://www.bisque.com/sc/forums/p/442/426.aspx

Don't forget to substitute the name of your camera for the one in the article.

[gregbradley]

Thanks for that.

In CCDsoft under the camera menu box and under colour.

I wonder if there is anything you can download to increase the number of columns in the colour tab in cameras. LRGB is all you can do when its often HaLRGB. It would be nice if it could be increased to 5 columns not 4.

Greg.

[frolinmod]

Greg, you're not the only one. I've seen that request before. Perhaps it'll get into the Camera Add On once it achieves parity with CCDsoft, assuming that is the goal.

[cventer]

For those we MX or ME when you are training PEC

Where are you pointing your OTA ? From the instructions it looks like we shoudl have dec close to zero and a star within 5 or 10 degrees from Meridean ?

Is this what you do ? I assume you dont want star to cross the merdean while logging data ?

Also the instructions say to orient camera so X = RA

Question i have is what is X relative to ? My CCD is rectangular. So shoudl X axis be across the long side ? Or do they mean x axis relative to the imaging software ie X axis is horizontal when looking at screen ?

In CCD soft my rectangular camera image is allways shown in Portrait mode. Ie longer side vertical in Y axis.

So do I irent camera to move star up and down the long axis when I move RA or sideways left to right on short side of rectangle when I move RA ?

Seems to be important to ensure DEC drift is not captured and only RA PE is captured.

[frolinmod]

Yes, that's where I do it, just to the West with the scope on the East side so that I don't have to worry about the post meridian stop. Of course with an MX you have much longer leeway (2 hours) there than I do with the ME (20 minutes), so you really don't have to worry about which side of the Meridian you're on.


You want RA to be X to be left right movement across your screen. You want DEC to be Y to be up down movement on your screen. Use image link to determine your position angle. Get it as close to zero degrees as possible. You really don't have to be all that close, the software doesn't really care that much, but it's helpful to be perpendicular so that you can see how things are going along while you're tracking and see how much drift is occurring either from polar misalignment or flexure. It doesn't matter that you have drift. That won't affect the measurement so long as the star doesn't drift entirely out of the track box while you're collecting data. I purposely use a large track box in CCDsoft so that I don't have to worry about drift at all, no matter how bad my polar alignment might be at the time.

Not really. I saw your graphs. They look good. That little amount of DEC drift is of no consequence to PE measurement. However, you really should improve your polar alignment (if that's what's causing the DEC drift) for obvious other reasons.

[cventer]

Thanks for response. I am posting my CCDSoft logs here attached to this.

I am pretty sure now that the graphs I postd on Bisque site are showing the dec drift and seeing and not RA and PE.

When I look at the raw data one of the correction streams seems to be a very straight line with oscillations around +1 and -1 pixels.

The other is also straight (with drift) but more osciallations that look more like a repeating pattern which suggest this is actualy my RA.

If so then I am concerned as this shows my uncorrected PE as being terrible (+8.4/-3.8) arcsec which seems not right either for this mount.

i was unsure of camera orientation when I tooks this so be curious if someone can tell from this data which axis is my RA and which is DEC.

[cventer]

I need to check this, but dont think I have too bad a drift as far as I can see. The star stayed in a 50x50 pixel box for 30 minutes with ease. In fact in 30 min it maved a max of around 8 pixels

[gregbradley]

Then your polar alignment must be sensational as that is not easy to do.

Greg

[frolinmod]

Oops, okay, then. In that case, during normal operation, Protrack might eliminate that. You're not allowed to use Protrack when measuring PE, of course.

[cventer]

Can someone who has done this before please review my log. Right now it looks like my mount is out of spec in terms of PE unless I am looking at wrong axis which I don't think is the case.

[gregbradley]

I opened up the file in Precision PEC. After the data is fitted (drift removed and scaled correctly) your data is -2.8 to +2.8 with the vast bulk of it between -1.4 to +1.4.

You have 4 large spikes that take it out to 2.8 from the 1.4 band. So its average is more like 3 arc secs and including the spikes you get 5.6 arc secs which is below their spec. As I recall their spec is 6 or so isn't it?
So I take it you have at least 4 rough spots on your worm and it may be only 2 that repeat. What is the period of the worm? About 4 minutes?

I could compare it with my PME's curve if you like.

As I recall my PME was about 3.5 arc secs peak to valley. I don't recall seeing the spikes but when autoguiding there is definitely a period where the guide errors go up a bit for about 20 seconds.

Greg

[cventer]

Thanks Greg

Can you post a pic of the scaled data in precision pec ?

Seeing was also really bad as you can see by all the spikes in the dec axis . Sounds like it just needs to run a few cycles.

I used the excercise mount feature today and had it run for nearly an hour slewing RA and dec from hard stops so that should help some.

I will try agian another night if these clouds ever clear.

[gregbradley]

Excuse my ignorance but how do you do a screen shot?

Greg.

[gregbradley]

As I recall the manual says not to do a PEC run in poor seeing. It would give an wrong PEC curve. What you want is typical seeing, usual conditions so the curve matches what is most often the actual.

Greg.

[cventer]

Depends on what OS you use.

In windows 7 there is a little tool in Accessories menu called snipping tool. Just draw a box around the screen with this tool and it grabs it.

Other way in any OS is simply when you have the screen showing. press left Alt key and the Prnt Scrn key at same time. This copies the active window into memory.

Open up photoshop and select new. It will create a new canvas the size of what you captured in memory. Hit paste or Ctl-V and screen will appear in photoshop. Do the normal save for web thing and you are done...

Seeng was not great but also not the worst it gets. It was probably a little higher than normal but not that far off.

I thought these programs were supposed to be able to remove seeing as a factor for the most part.... ?

[gregbradley]

Hi Chris,

I used the snipping tool.

See the attached.

Greg

[gregbradley]

And the final PEC curve that would be uploaded into the PMX on board memory:

Greg

[cventer]

Thanks Greg,

Although looking at that data I am pretty sure its loaded the wrong axis. That looks like DEC drift data and seeing to me. Plus my image scale was 1.82 which makes things a little worse.

Gues its shows the seeign was pretty bad though jumping around by anywhere from -2.8 to +2.8

Cheers
Chris

[gregbradley]

Hi Chris,

It looks like my PE graph. My data had a drift in it as well.

Greg.

[gregbradley]

I receive my PMX tomorrow. I'll have it up and running fairly quickly. So I can compare notes with you. Also some clear nights in the forecast are coming up.

Greg.

[cventer]

Nice

You must be very excited. But owning an ME you already know what you are getting in terms of quality.

Did you get a tripod for your as well ?

[frolinmod]

Speaking of tripods, I've had my Rob Miller TRI36H tripod partially out in the sun for several months now. The top part has been covered, but the bottom half has not. The bottom half is becoming sun bleached. It's turning pink. :rolleyes:

I think you can see this fairly well in the attached images.

[cventer]

Interesting to know that re miller tripod. My Miller tripod arrives tomorrow. The accessory package arived last week and legs tomorrow. The micro levelers are the new enhanced ones and are works of art.

[gregbradley]

I have a solid steel "portable" pier that I will use. At my dark site I have a pier embedded in concrete.

I will bolt the aluminium adapter plate to the pier plate to mount the mount.

My home observatory was designed for 2 setups, the CDK17 on a PME and the steel pier
with refractors.

So the Miller tripod is fading in the sun?

Greg.

[Mighty_oz]

Pics please :) hehe

[cventer]

When tripod Arives I will take pics

[cfranks]

My MX seems all over the place but I assume it is me somehow. :( - I did an auto claibration run of 50 points and got a error circle of 15.6 arc sec. Did another of 93 points and the error increased to 44 a.s. I thought I would try a PEC but how do I get the Log it wants? I seem to have missed that part of the docs.

Charles

[cfranks]

I think I found the instructions but it's now completely clouded out. Try again tomorrow.

Charles

[frolinmod]

I use CCDsoft as per Tom's Corner here: http://www.bisque.com/tom/PrecisionPEC/mypec.asp

Note that Tom writes about doing this for an ME using PrecisionPEC, but PrecisionPEC is fact now built into TheSkyX's Tools->Bisque TCS->Periodic Error Correction->Compute PEC Curve, so PrecisionPEC is no longer needed. The procedure is the same for the MX.

If you guys haven't already been all over Tom's corner, you should! It's geared to the TheSky6 and the ME, but still very much applies to TheSkyX and the MX with a little "translation." Tom accumulated many years worth of experience in his little corner there. It should not be lost.

Tom's Corner: http://www.bisque.com/tom/tom.asp

Tom's Corner Paramount ME: http://www.bisque.com/tom/Paramount/paramount.asp

[cfranks]

Thanks Frolinmod, I had seen that article but didn't think it applied since I don't have an ME, Sky6 nor PrecisionPEC. I'll have another look tonight.

Charles

[cventer]

The one thing in instructions I am not sure about is using very short exposures when capturing the PE log in ccdsoft.

Surley this means you are capturing the variabililty in the seeing ?

Would it not be better to take 2 or 3 sec exposures to average it out ?

I read a few posts on Paramount yahoo group where 3 - 5 sec exposures are being used.

What do you guys think ?

[gregbradley]

My PMX arrived today. I am off to set it up.

You never know it may even be clearish tonight.

Greg.

[Bassnut]

Yes, chasing seeing would make PEC a mess. 5secs or more would Be the go, depending on seeing. Although there is some smoothIng effect with a few runs, and PE tends to change over 10s Of seconds.

[cventer]

Is it normal with Bisque TCS software that when you capture pec data pointed east of meridean you need to tick the box in PEC within The Sky X to indicate data was captured on the west ?

I found that even though I captured data on east. ie scope was pointing east of mediean if I did not tick the box saying it was west my PE got worse.

I am not that happy with the impact turning PEC on has had. It has slightly reduced the PE but not by very much. probably only 2 arc sec total. be interested in any other southen hemisphere users if they have used PEC yet on MX and your experience.

[cfranks]

There is a very confusing staement about this, by Tom Bisque. AFAICS, the telescope is West if it is pointing East and the box has to be ticked. I haven't got anywhere near this as I am still getting '655' errors. The MX is a brilliantly made item but the software leads something to be desired. That and the Plurry clouds. :sadeyes:

Charles

[cventer]

Thanks Charles. I have found software to be realy good so far other that few issues that daily build adds every so often.

What's a 655 ? What are you doing when you get this error ?

[nickbtx]

Chris,
From my experience, not only does the software require that RA has to be the "X" axis (horizontal), but it expects west to be to the left and east to the right (north up). If my camera is upside down, I have to check the box indicating it was recorded in the opposite side of the sky. I'm in the northern hemisphere so what I'm seeing may not apply to the southern hemisphere. You may have to determine what is "normal."
Nick

[gregbradley]

I haven't used PEC with the Sky X although I am about to. But with Precision PEC there is a button about east and west and an auto button for the software to check it.

This is the one I had back to front that caused my PEC to worsen guiding.

With it running it does improve tracking and took me the rest of the way to round stars. My PEC curve is a very minor curve with only small corrections.

I can take a screen save of it if you like.

But I will know more about the PMX one shortly. I got the idea Pempro was a bit more accurate than Precision PEC. You can always use that instead.

Greg.

[frolinmod]

The exact same thing happened to me with an ME. I reported it, but they acted like I was nuts. I didn't really know if it was me or them that was nuts. I'm still not sure! In any case, if it comes out twice as bad, you just reverse the check box and reprogram. No big deal.

By the way, I don't know if PEMpro knows about the MX yet. I understand the mount fundamentals and the PEC table are different than the ME.

[cventer]

Thanks. I have my camera ra on x. But not sure about east and west. I tried clicking the "data caputred on west button on and off". With clicking the west my PE reduced a little. with it not clicked it got worse. problem is it did not reduce nearly enough. ie it did not take out the PE properly and in fact made things worse than no PE it all.

Last night there were a few breaks in clouds. I did a 30 sec shot with PE on. Looked like sideways logs. turned PE off. and round stars.

Something is just not right. I posted on Bisque forums so will see. I have worked out though that without PEC my mount is actualy within spec. Its about plus or minus 3 right now. When I did first check I thought my image scale was 1.83 but turns out it was .87. So at least i know its within spec. I just cant seem to reduce the PE very much with PEC. I can increase it or reduce it by about .5 or an arc sec but I am expecting it to go go less than 1 peak to peak with PEC and its no where near that

[frolinmod]

I hope after properly programming the PEC you'll eventually get your MX down below one arcsecond PE. My ME came with about 3 arcseconds peak to peak of PE that reduced to sub-arcsecond when programmed. I can't think of any reason why the MX should be any worse.

[gregbradley]

There is no auto check button like in Precision PEC? I am not up to that point yet. But Precision PEC has an auto east/west button.

Back to front your mount is reversing the PEC curve making things worse not better.

Greg.

[Bassnut]

but what seeing whilst PECing, I've never quite wirked it out, but if seeing was 2-3 arcsecs how can you hope to get a curve down to 0.5?

[gregbradley]

The PEC software promotes that fact it can work out PEC and get past the seeing.

I guess the way it does that may be mathematical in that seeing would be irregular and erratic and smoothing would remove that influence. Much like median combine gets rid of artifacts.

Having said that I would have to think that PEC data done on a stable night would give you a better chance than on a bad night. Bad seeing in my CDK17 really shows up horrendously. Fortunately it is not that shocking very often.

Greg.