Thank goodness your back Cuiv, as well as turning me on to N.I.N.A your videos have steered me through most of the problems I have come across as a beginner astophotographer. Thanks for all your time ,effort , and enthusiasm.
Thanks so much for sharing this Cuiv! I have some eccentricity in my EQ6R RA motor that causes a 120s PE that I can't get rid of with the mount's bulit in PEC, and this should be a great way to deal with that. BTW you probably know that is but you can use the "analyis" feature in the guidelog to look at the period of that sine wave.
Great video, Cuiv!! I've been using PHD2's PPEC algorithm for over 2 years with my iOptron GEM45 mount, and can't live without it now. The guide performance in RA axis is no match when you look at the guide graphs on the guide log side by side, and would highly recommend any of the beginning astrophotographers to use this algorithm on PHD2. I usually guide with an OAG and the shortest focal length I use is about 900mm+. On such system, I use higher aggression and higher values for retaining the periodic error on the advanced (brain) settings due to terrible seeing conditions in the middle of Seoul. I would also highly recommend not to use auto find setting for the worm period. I found that guesses the PHD2 is quite finicky, and I sometimes get something like 2.5 times the worm period (how does it guess such a figure!!) and get terrible guiding results if I leave it at auto. I use the worm period in the spec sheet of the mount, and it works perfectly
Thanks for the feedback! You're brave using such long FL in such poor seeing (I think Tokyo and Seoul have equally bad seeing...). Interesting on the worm period, thanks for the tip!
Thanks for this comment. I was going to ask about the gem45 as it is my understanding that it has built in encoders which Cuiv stated might make PEC suboptimal. Based on your experience I will try it myself.
Great video and explanation! Is Phd2 smart enough to learn this while doing short exposures and dithers, or would it benefit from being left alone to guide uninterrupted for 10-15 min before you start imaging?
Another great video Cuiv I'll be using this setting in PHD2 next time I image as my guiding can be very hit & miss sometimes, thanks for your time uploading & explaining this clear skies!!
Great video. Thanks! Concerning RMS errors, (Total, RA & Dec) I am sure you are aware that this is actually a right triangle with the hypotenuse being Total RMS. The side adjacent and side opposite represent the DEC and RA. If the DEC and RA are unequal then the stars will be egg shaped. But if they are equal (or at least close to equal) then the stars will be round. OK fine. I have searched and searched trying to find the adjustments (in PHD2) that will help to achieve this without any luck. I have come close adjusting the RA minmo and the DEC minmo but the results are far from stable. Any thoughts on this? Anyone?
Heck no! That's far too much work and I already know from the result of the PHD2 PredictivePEC that there is very little room for improvement, so ROI on spending the effort to do so would be quite bad
Thank you for all your help with astro gear! I have learned so much from you! Question: I have aa C14 on the CEM60EC mount (which has RA encoder) Do you know what PHD2 algorithm I should use with the encoder? Would I be better off to turn the encoder off and allow PHD2 to correct for both mount axis errors? I am running at F7 with the ZWO071MCpro camera at bin2 and off axis guider ZWO290mm mini. Thanks
Just a quick follow up. My guiding improved by about 25% like you said...total RMS 0.50" from 0.70". Not sure why this hasn't been discussed before so thanks.
Great video. One mystery for me on all these settings is which software does it in a multi-software environment? I run stellarmate as my core O/S but get it to use PHD2 as the guiding interface. Do I do these settings in PHD2 or Stellarmate, do you know if Stellarmate overides PHD2 settings?
Yeeesss, one more step towards the dark side of UA-cam. Now time to learn how to do the UA-camr face and you'd be set LMAO Nice work here, pretty sure I haven't seen anyone explain this. Now I'm wondering if ZWO implemented something similar in the ASIAir; yes I know they ripped off a lot of stuff from open source software (the multi-stars guiding was supposedly one of those), not sure if this is included. Yes I really have to wean myself from the big bad red, but eh, I need to maximize the silicon and metal used to build this thing. ¯\_(ツ)_/¯
Glad to see you back Cuiv, rested and sharp. Great vid, as usual^^ I'm using it since its implementation on a SW AZ-EQ6 with a SC 8", which cut my RMS and peaks in half. NB : polar alignment, weight distribution and calibration must be perfect.
As usual another great video Cuiv. Thanks for taking the time to pull it together. BTW - You should enable DEC Backlash Compensation and back-off on your Resist Switch Aggressiveness a bit.
Thanks Jim! I've had bad experiences with the backlash comp in the past, and with the CEM60 meshing that can be variable depending on the clutch I'm wondering if it would work well... I'll have a look!
With the EQ6-r and EQMOD, PPEC and guiding don't fight like they do on iOptron mounts. The combination works great together! The same is true or Astro-Physics mounts.
Thanks Linda, That was my quesrion for Cuiv. So I’ll try both of them together. Without corrections on my EQ6-R, PHD2Guiding shows an RMS of 0,78”. Let’s try if I can ger this value lower.
Although to be fair, as far as I remember EQMOD does cut off some guide pulses when they conflict with the PPEC (Greenswamp Server has a specific mode to combat this). Might be misremembering though!
I thought you were gonna talk about the east heavey method and almost didn't watch the video. Never heard of this method so thank you very much. Glad your back.
Note that KStars has this as well; I also just implemented a feature to decouple the predictive corrections from the guide camera corrections, so you can take long guide exposures if necessary, while responding to predicted PE much more frequently :)
@@CuivTheLazyGeek This is not “real” AVX. It is just AVX shell (made in 2016). Inside everything (bearing lubricant motor parts) US made, except electronics. I basically remade everything inside. One more thing, I guide with 0.5 sec interval. This very important.
Yep I have a CEM26 and without PPEC the guiding goes all over the place out of no where even with perfect polar alignment and perfect gear mesh / belt tension. I did just realize that my rig got a bit to heavy so making sure you are not more than double your mount's capacity helps too. Not everyone has a CEM60 LOL.
I am so glad I found this video. I have been struggling to learn how to understand my PHD2 log information and this really helps. Keep up the great work Cuiv.😊
I recently upgraded from DSLR to QHY 183 M with the 7 position filter wheel but I'm stuck finding the right fitting to connect my Televue Paracorr type 2 coma corrector to the QHY filter wheel. Any experience with that coma corrector and a Newtonian?
Great advice Cuiv! I have the Orion HDX 110 Mount and routinely get around .52 arc seconds total error, which is already really good so I can imagine what predictive PE might do. I have been known to get a quarter arc second before but I'm not sure why it was so good. I did add around twelve new calibration steps. Perhaps that was it? Thanks for the advice.
Thank you Cuiv, I have been using PHD2 for years but was not aware of this. I will try it next session. You have a great way of explaining things and this is very helpful.
wow very interesting. do you have any videos on a backyard DIY 21cm 1420 MHz radio telescope dish and how to track hydrogen objects with an equatorial motor control? 😎 thank you.
I wonder if the periodic error is changed by different loads. What I'm trying to ask is, say i do planetary one day and the next day I put a heavier camera and filter wheel on? Will predictive PEC save more that one profile or would you say that this function only depends on the error in the gears, irrespective of the load on the mount? If it does make a difference and PHD2 only saves one profile, perhaps this would be an upgrade to propose to the creators of the program?
Thanks for the tip. I will try this out. I am trying to guide out a C14 and the RA does show some periodic fluxes. I hope setting to predict PEC setting will help.
Like every one here said: Another great video!! We missed you ! Question could you explain the chart you show at 1:34 ? Also, there's no advantage in getting a mount with built in PPEC?
Using PPEC and PEMPro together seems to work well with my Losmandy G11 with Gemini. The 240s error is reduced by PEMPro to some degree but the PPEC picked up the most of the residuals. But PPEC does not seem to have the ability to reduce multiple overlapping worm harmonics, e.g. it will handle the 240s error well but not the 120s, 80s or 60s; all fundamentals of the original worm period. A more advanced PPEC that could handle more frequencies at once would really be worth while. Thanks again for your feedback. John
Great video, Cuiv!!! For those reading, it is possible to right click in the PHD2 log viewer to do a frequency analysis and it will tell you the periodic error to help in analysis. Great for talking with the PHD2 devs or mount support gurus as well!!
Thank You, Cuiv. Little Pearls like this make life better. I'd say after the multi-Star guiding, this can really help automate the guiding process. A friend of mine gave multi-star out as soon as PHD2 allowed it to be given. He was a part of the Beta team helping to work out the release. I do have a question though, why do you have your settings so broad where you show Plus/Minus of 30°? I try to run my graph much, much lower so my graph is choppier. Mainly just curious, because I've observed this a lot when folks start demonstrating their graph's. Or is it to get a much broader view of time? Love your tutorials! I've already applied this to my "Mount Computer" that I use outside. (I remote operate most of the time. I'm old, and the cold bothers me.) Again, Thank You!
You referring to the guide graph scale in PHD2LogViewer? I think the scale defaulted to that when I opened it - also I don't want to scale it too much because then I might start getting obsessed with the guide performance!
Ah maybe my guiding will be more stable. I can get into the low .40's arcsec/pix, but then out of nowhere it goes to over 1.0 arcsec/pix. Very frustrating. I'm always watching it.
Didn't know about that one Cuiv!. Thanks for that, I will definitely be giving it a go next clear night. I do have sine wave discrepancies on my guiding for sure.
Great tip Quiv, didn't know that so have to try this out if I can get some clear skies here in Belgium. Question though, your title says "not multi stars" but in the video you write to enable multi star guiding ?
In my latest video :) Guide scope normally doesn't matter much in Tokyo (because terrible seeing) as long as it's well paired with the FL of your main scope...
Cuiv, do you happen to know if there are PhD2 log files in the ASIair app that can be viewed on the PhD2 viewer? I would like to be able to view my periodic error, but I just recently switched from using Ascom and third-party software like APT and N.I.N.A to using ZWO’s ecosystem. Currently my total RMS error is between 0.6”-0.8” on my AVX mount using the “lite” PhD2 guiding within ASIair. I suppose if anything I can always still connect my AVX to the “other system“ to do the PhD2 log file but I’m getting spoiled with the ASIair. Like most of the other nerds and engineers watching your videos I appreciate your time explaining new topics like the way you do.
Cuiv, I just checked my images on my last session and there is a log file for the PHD2 output. It works with the PHD2 log viewer that you mentioned. When you transfer your image files from the thumb drive there is a log folder that has the log files in them. Just for all your viewers to know for sure you can still use the log viewer to see your performance of the mount with the ASIAIR.
Hi Cuiv, your video is interesting but but I think you have misinterpreted the results. RA error is roughly proportional to cos(Dec) and if you compare your mount performance at different declination you will measure different errors. So, if your error at the equator is 1" at 60 degrees it would be 1" * cos(60) = 0.5" so applying this equation to California nebula (dec = +36 degrees) and Heart nebula (dec = +61 degrees) we get cos(36) = 0.81 and cos(61) = 0.48, and this makes 0.81/0.48 = 0.59, which means about 40% improvement, which is pretty much in line with your claim of 30% improvement with PPEC on. I have a paper on that and if you want I can share it. So, I am not sure the improvement comes from the PPEC, but I am pretty sure it mostly comes from the tracking on a higher declination. I would advise you to repeat the test at the same declination with and without PPEC, with same settings (guiding exposure, aggressiveness etc) and then draw any conclusions.
I'd like to see that paper! I can understand why the error in pixel (for RA guiding) would be proportional to cos(dec), but arcangle (and guide pulse lengths required for corrections) should be unchanged. As far as I can tell the only thing changing would be the precision of the deviation measurements that gets worse the closer to the Celestial pole since the same arcangle of deviation would cover fewer pixels. And of course the impact on the final image of the same guiding performance would be diminished then. To be sure I tested PredictivePEC and Hysteresis just now staying on the California and then the Heart Nebula, and I could reproduce my previous results on both (guiding perf sensibly the same between the two targets, PredictivePEC sensibly better than Hysteresis on both)
@@CuivTheLazyGeek Looks like if I put the link UA-cam refuses to publish my post. I will send the paper on FB. But generally, i do not claim PPEC does not help I just say that there may be another explanation. And I do understand your confusion. The difference in arcsec comes from the fact that the mount has certain error in RA axis. And the further to the pole you go the smaller its projection as the circle followed by RA is smaller. The guiding error is always measured on a great circle while RA error projection will be 1:1 only on the equator (on a great circle). While declination always follows a great circle.
RA errors are proportional to cos(Dec). Dec of the California nebula is 36 degrees, and Dec of the Heart nebula is 61 degrees. Therefore, the ratio of the two RA errors would be cos(61)/cos(36) = 0.60. From the guide logs, the ratios were 0.37/0.61 = 0.61. So it seems to me that there was no difference in guiding performance between the two session, if you take the declination of the targets into account.
Cuiv, there is nothing lazy about the depth of what you’re sharing and for the engineer audience you can’t say too much! Now i have to wait for the next clear night to give this a try. Thank you!
On my mount, EQ6.R, this sinusoidal periodic error is MUCH MORE pronounced. Why is that? I don't see it being this bad for anyone else, is my mount extra poorly made?
@@CuivTheLazyGeek I have made sure of not making that mistake. I do also believe I have the guide scope focal lenght and guide camera pixel size set correctly. I does not just feel like a difference in the amplitude of the sine wave., so many abrupt jumps on the guide graph. I have heard from others for whom PHD2 was able to remove most of the PE, without any PEC. Adding PEC only made marginal improvements for them. Also, my DEC is quite bad, around 0.80''. Ra is at about 0.9''. Which gives about 1.22''. There are several 4'' peaks in both axes. Many 2-3'' jumps between two consecutive frames. I mean that's not really horrible I guess, but worse than what I had expected from roaming the internet. So, there could be other issues that is making the graphs look bad. Hardware, software and so on. Or I am expecting to much. Or it could that there is consistently bad seeing here in Sweden. Or my expectations are too high.
RA axis only moves forward (or at most pauses) to adjust its movement, while Dec with perfect polar alignment should in theory be completely static. In practice it goes back and forth as needed - predictive PEC therefore doesn't make sense for Dec!
Nice video as always. I looked for the optional algorithns in the settings and the pull down menu was inactive (greyed out if you will). Is this s version thing or is there another stting that inhibits this? Also, do you have the PEC playback (I have an AVX mount) active when you guide like this?
@@CuivTheLazyGeek Thank you. It was guiding. I just looked at it when unconnected and the menu option is there. Somethings seam more obvious in daylight. As soon as the weather cooperates I will disable PEC playback and give is a shot,
Hello Cuiv, thank you for this video. Unfortunately I cant read anything of your recording because UA-cam wants money from me to buy premium to get 1080p otherwise I only can stream 360p which is, for a channel about visual stuff, not useful. Maybe you can zoom in to the interesting points or read the values of your screen next time.
That's 100% a UA-cam bug - it should provide the 1080p normal option, and as far as I can tell only this video is affected. For now, I've used the UA-cam Studio editor to add a random blur in one second of a video. This should force UA-cam to reprocess the video, and maybe fix the issue.
@@CuivTheLazyGeek Thank you very much, you're the best! Is see clearly now, the blur is gone. You are a human BlurXterminator :) BTW ontopic: yout Trick worked great!
In the photography world we have a lot of cameras with image shake reduction hardware that the sensor is attached to. Seems to me this would be an excellent way to tackle some of these areas - basically in camera. Perhaps this is not really a good solution or the market is not pressuring the manufactures to build it.
That's exactly what Pentax Astrotracer is ;) And Olympus' derotator patent. Would be great to have physical optical stabilization on astrocameras so guiding corrections could be done in camera but the range is small and there's a whole cooling element stuck to the sensors backside!
@@CuivTheLazyGeek I was aware of Pentax's feature, but not Olympus. I forgot about the cooling problem - I suspect if the motivation is there it could be solved. Which leads me to ask - just how big of a range would one need (assuming a reasonably good mount).
Absolutely amazing to have to you back mate! Just learned something new from you (again)… Will implement this as some as weather improves here in Melbourne … now I have to remind myself how to turn off PEC corrections from my mount - EQMOD😂
Fantastic video!! Honestly this has been very useful and I look forward to seeing if I can improve my guiding with this method… however I use ASiair plus, do you know if the ASiair has this setting? I’ve not noticed in the settings, but I do notice a similar wave pattern on my guiding… I use an EQ3 pro mount. Thanks
@@CuivTheLazyGeek ah ok thanks Cuiv, I think I may have to try PHD2 guiding by itself in one of my next few sessions. My guiding has improved a lot recently by carrying out PA at least twice and making sure that I calibrate the guider everytime. But I do still notice the wave pattern. I could never figure out what could be happening so I’d try adjusting the aggression but ultimately because the guiding is usually around 0.7 arc seconds I haven’t been too troubled. But a fantastic video that really makes you realise there is much more to many aspects of AP than you would at first think. I never considered impurities in the worm and I do have one of the cheaper mounts too haha
I will definitely try this the next time I image. Guiding can be such a mystery at times, the last two months I was really frustrated I went from an average of error of 0.7 to 1.0 to 1.5, last time I imaged it was back down to 0.6 the difference being the seeing conditions were really good, prior to that they were not. I don't suppose this would have much affect when seeing conditions are poor?
With really bad seeing it would be less effective, although since it's looking for Fourier frequencies, it should still make a difference by properly recognizing periodicity
Seeing and relative humidity are huge factors. My summers are quite humid and my normal RMS shoots up by 0.30 easily. Dry winters nights are much easier to guide.
This video dropped just in time! I literally looked up which PHD2 algorithms were better to use a couple of days ago and ended up settling for PPEC, which was one of the most recommended. Glad to know how that works now :)
Cuiv, very well done explanation of cause and effect. This was done so well, I would suggest you consider doing slightly expanded version some Sunday on The Astro Imaging Channel (TAIC). They are always looking for great presentations.
On my Skywatcher HEQ5 mount which definitely exhibits PE in RA. I generally get good enough guiding total RMS around 1 arc sec but also annoying “random” excursions in RA up to +/- 4 arcsecs which does seriously affect my images. Pete.
So great to have you back to making astrophotography videos again, Cuiv! I've always learned so much from you and this video is no different. I will be giving this a go next imaging session. Thanks for all of your help and tips over the past couple years. Take care, Cuiv.
You are a legend Cuiv. Why am I only hearing about this now? Can't wait to give this a go. Thanks
Hope it works out for you!
Thank goodness your back Cuiv, as well as turning me on to N.I.N.A your videos have steered me through most of the problems I have come across as a beginner astophotographer. Thanks for all your time ,effort , and enthusiasm.
Glad it's helpful!
I am happy to see your videos back. Theorical and practical is what I love. This is what defines an engineer. Keep going.
Thank you - I'm glad to hear my long-winded explanations are appreciated :-)
I m so thankful that there are people like you out there. What a legend !!!
Thanks so much for sharing this Cuiv! I have some eccentricity in my EQ6R RA motor that causes a 120s PE that I can't get rid of with the mount's bulit in PEC, and this should be a great way to deal with that. BTW you probably know that is but you can use the "analyis" feature in the guidelog to look at the period of that sine wave.
You really do a great job of explaining things so that us newbies can understand the problem you are solving. Thanks for another great video.
Really happy to see such feedback, thank you :-)
Great video, Cuiv!!
I've been using PHD2's PPEC algorithm for over 2 years with my iOptron GEM45 mount, and can't live without it now. The guide performance in RA axis is no match when you look at the guide graphs on the guide log side by side, and would highly recommend any of the beginning astrophotographers to use this algorithm on PHD2.
I usually guide with an OAG and the shortest focal length I use is about 900mm+. On such system, I use higher aggression and higher values for retaining the periodic error on the advanced (brain) settings due to terrible seeing conditions in the middle of Seoul.
I would also highly recommend not to use auto find setting for the worm period. I found that guesses the PHD2 is quite finicky, and I sometimes get something like 2.5 times the worm period (how does it guess such a figure!!) and get terrible guiding results if I leave it at auto. I use the worm period in the spec sheet of the mount, and it works perfectly
Thanks for the feedback! You're brave using such long FL in such poor seeing (I think Tokyo and Seoul have equally bad seeing...). Interesting on the worm period, thanks for the tip!
Thanks for this comment. I was going to ask about the gem45 as it is my understanding that it has built in encoders which Cuiv stated might make PEC suboptimal. Based on your experience I will try it myself.
Excellent tip and explanation. Off to check my PHD2 log.
Have fun!
Great video and explanation!
Is Phd2 smart enough to learn this while doing short exposures and dithers, or would it benefit from being left alone to guide uninterrupted for 10-15 min before you start imaging?
As long as you do this without slewing the scope, yes!
Another great video Cuiv I'll be using this setting in PHD2 next time I image as my guiding can be very hit & miss sometimes, thanks for your time uploading & explaining this clear skies!!
Good luck!
Great tip! Never heard of it before! Gonna try it soon, thanks!
Enjoy trying it!
Thanks for sharing this video Cuiv!
You mention "not multi-star" but wich is better to use with Predictive PEC, sigle star or multi star?
Multi-star is always better, regardless of what else is used!
Excellent video Cuiv! I kind of wondered if ppec and phd2 were fighting each other or not, so I quit enabling ppec. I will try this. Thanks!
Good luck!
Great video. Thanks! Concerning RMS errors, (Total, RA & Dec) I am sure you are aware that this is actually a right triangle with the hypotenuse being Total RMS. The side adjacent and side opposite represent the DEC and RA. If the DEC and RA are unequal then the stars will be egg shaped. But if they are equal (or at least close to equal) then the stars will be round. OK fine. I have searched and searched trying to find the adjustments (in PHD2) that will help to achieve this without any luck. I have come close adjusting the RA minmo and the DEC minmo but the results are far from stable. Any thoughts on this? Anyone?
This is very useful Cuiv. Have you compared phd2 pec results vs doing a pec training within eqmod?
Heck no! That's far too much work and I already know from the result of the PHD2 PredictivePEC that there is very little room for improvement, so ROI on spending the effort to do so would be quite bad
Thank you for all your help with astro gear! I have learned so much from you!
Question: I have aa C14 on the CEM60EC mount (which has RA encoder) Do you know what PHD2 algorithm I should use with the encoder? Would I be better off to turn the encoder off and allow PHD2 to correct for both mount axis errors? I am running at F7 with the ZWO071MCpro camera at bin2 and off axis guider ZWO290mm mini. Thanks
I think a lot of people had issues with sub division errors with encoder + guiding forthe CEM60. You should check on Cloudynights
Your are an excellent teacher. Where were you in college??🤣🤣
Hahaha maybe I should become a teacher :)
Just a quick follow up. My guiding improved by about 25% like you said...total RMS 0.50" from 0.70". Not sure why this hasn't been discussed before so thanks.
I have exactly this problem with AR, but I use ASI AIR, do you know if there is a way to correct it on ASIAIR as you did with PHD2?
Excuse me while I bookmark this.
Hahaha thanks :-)
Great video. One mystery for me on all these settings is which software does it in a multi-software environment? I run stellarmate as my core O/S but get it to use PHD2 as the guiding interface. Do I do these settings in PHD2 or Stellarmate, do you know if Stellarmate overides PHD2 settings?
I think Stellarmate would completely rely on PHD2 if setup to use PHD2, so it should be set there
Hello my friend. Have you also tested at the Zenith? Looks like it is not good in the Zenith. Pls let me know.
Do you mean at the celestial equator? Zenith is fairly irrelevant for equatorial mounts
@@CuivTheLazyGeek sorry, i meant near ecliptic is worst
Yeeesss, one more step towards the dark side of UA-cam. Now time to learn how to do the UA-camr face and you'd be set LMAO Nice work here, pretty sure I haven't seen anyone explain this.
Now I'm wondering if ZWO implemented something similar in the ASIAir; yes I know they ripped off a lot of stuff from open source software (the multi-stars guiding was supposedly one of those), not sure if this is included. Yes I really have to wean myself from the big bad red, but eh, I need to maximize the silicon and metal used to build this thing. ¯\_(ツ)_/¯
They might implement it after this video ;-)
Clickbait video caption. Nearly.skipped the vid. Why would any manufacturer 'hate' this?
This was intended as a tongue in cheek parody of all the "doctors hate this one trick" ads that can be seen on a lot of websites :-)
Glad to see you back Cuiv, rested and sharp. Great vid, as usual^^
I'm using it since its implementation on a SW AZ-EQ6 with a SC 8", which cut my RMS and peaks in half.
NB : polar alignment, weight distribution and calibration must be perfect.
Great video as usual. Your contributions to amateur astronomy community have been incredible I can't thank you enough.
Thanks Rich! Although the PHD2 dev deserves all the acclaim!
As usual another great video Cuiv. Thanks for taking the time to pull it together. BTW - You should enable DEC Backlash Compensation and back-off on your Resist Switch Aggressiveness a bit.
Thanks Jim! I've had bad experiences with the backlash comp in the past, and with the CEM60 meshing that can be variable depending on the clutch I'm wondering if it would work well... I'll have a look!
With the EQ6-r and EQMOD, PPEC and guiding don't fight like they do on iOptron mounts. The combination works great together! The same is true or Astro-Physics mounts.
Thanks Linda,
That was my quesrion for Cuiv. So I’ll try both of them together. Without corrections on my EQ6-R, PHD2Guiding shows an RMS of 0,78”. Let’s try if I can ger this value lower.
Although to be fair, as far as I remember EQMOD does cut off some guide pulses when they conflict with the PPEC (Greenswamp Server has a specific mode to combat this). Might be misremembering though!
@@CuivTheLazyGeek That might be true if you are using EQMOD's PPEC, but I used PEMPro to write a curve to the mount so EQMOD isn't aware of it.
I thought you were gonna talk about the east heavey method and almost didn't watch the video. Never heard of this method so thank you very much. Glad your back.
Note that KStars has this as well; I also just implemented a feature to decouple the predictive corrections from the guide camera corrections, so you can take long guide exposures if necessary, while responding to predicted PE much more frequently :)
That is awesome to hear Sophie, and yes that's a great feature, keeping with the predictive corrections while the next guide image is being taken :-)
Took 9 minutes of watching the video to find out I'm already implementing the correction.
I love the silly click-bait sub-title in the thumbnail!!!
I'm so glad you got the joke!!! Apparently some were a bit offended by the thumbnail, not realizing it is tongue in cheek!
This is a reason I get 0.5-0.6 on AVX with 25Lb load. I experimented with different algorithms; it gave best results.
That's excellent for any mount, even more so for an AVX!
@@CuivTheLazyGeek This is not “real” AVX. It is just AVX shell (made in 2016). Inside everything (bearing lubricant motor parts) US made, except electronics. I basically remade everything inside. One more thing, I guide with 0.5 sec interval. This very important.
SW EQ6R = really good with PPEC and guiding, iOptron CEM26 = useless if you use PPEC and guiding at the same time.
Yep I have a CEM26 and without PPEC the guiding goes all over the place out of no where even with perfect polar alignment and perfect gear mesh / belt tension. I did just realize that my rig got a bit to heavy so making sure you are not more than double your mount's capacity helps too. Not everyone has a CEM60 LOL.
Excellent - cant wait to put this to use! As a beginner in the hobby I cant express enough appreciation for your videos - thank you Quiv!
Glad it's helpful!
I am so glad I found this video. I have been struggling to learn how to understand my PHD2 log information and this really helps. Keep up the great work Cuiv.😊
Recently got a used CEM60EC, the tracking performance is so good.
Thanks, Cuiv ! I always wondered how to get a better, flatter graph even with multi-star. Great explaination!
I recently upgraded from DSLR to QHY 183 M with the 7 position filter wheel but I'm stuck finding the right fitting to connect my Televue Paracorr type 2 coma corrector to the QHY filter wheel. Any experience with that coma corrector and a Newtonian?
Great advice Cuiv! I have the Orion HDX 110 Mount and routinely get around .52 arc seconds total error, which is already really good so I can imagine what predictive PE might do. I have been known to get a quarter arc second before but I'm not sure why it was so good. I did add around twelve new calibration steps. Perhaps that was it? Thanks for the advice.
Very sophisticated and well explained!
Thank you!
Thank you Cuiv, I have been using PHD2 for years but was not aware of this. I will try it next session. You have a great way of explaining things and this is very helpful.
Hope it works out well for you :)
wow very interesting. do you have any videos on a backyard DIY 21cm 1420 MHz radio telescope dish and how to track hydrogen objects with an equatorial motor control? 😎 thank you.
Thanks Cuiv! What a brilliant educational vid. I will try out this PPEC on my SW HEQ5 Pro Mount the next time i'm imaging
I wonder if the periodic error is changed by different loads. What I'm trying to ask is, say i do planetary one day and the next day I put a heavier camera and filter wheel on? Will predictive PEC save more that one profile or would you say that this function only depends on the error in the gears, irrespective of the load on the mount? If it does make a difference and PHD2 only saves one profile, perhaps this would be an upgrade to propose to the creators of the program?
Discovered this algorithm back when I had my CGEM, didn't help too much, but it really did when I got my EQ6R.
It's really mount dependent, glad it's working well now!
Thanks for the tip. I will try this out. I am trying to guide out a C14 and the RA does show some periodic fluxes. I hope setting to predict PEC setting will help.
Like every one here said: Another great video!!
We missed you !
Question could you explain the chart you show at 1:34 ?
Also, there's no advantage in getting a mount with built in PPEC?
That little change is amazing. My guiding went from about 0.85 arcseconds to about 0.55 arcseconds. absolutely amazing!!! thanks for the tip.
Awesome! Super happy it might such a large difference!
You keep making us smarter! Thank you.
Appreciate all you do for the astro community. Thanks, Cuiv !!
Glad it's helpful!
Brilliant, Cuiv! You’ve changed/ improved our imaging forever! Award this man a medal!
Thanks for the feedback as always Melvyn :-)
Using PPEC and PEMPro together seems to work well with my Losmandy G11 with Gemini. The 240s error is reduced by PEMPro to some degree but the PPEC picked up the most of the residuals. But PPEC does not seem to have the ability to reduce multiple overlapping worm harmonics, e.g. it will handle the 240s error well but not the 120s, 80s or 60s; all fundamentals of the original worm period. A more advanced PPEC that could handle more frequencies at once would really be worth while.
Thanks again for your feedback.
John
Great video, Cuiv!!! For those reading, it is possible to right click in the PHD2 log viewer to do a frequency analysis and it will tell you the periodic error to help in analysis. Great for talking with the PHD2 devs or mount support gurus as well!!
Thanks for the additional tip Steve, I didn't know that!
Any chance to do that in an ASIair as well??
What about the azeq5. It has bad encoders I think. Should I enable ppec?
I don't remember exactly, but I don't think those encoders are used while tracking, so it probably is fine. Safest bet would to simply disable them!
Would running both permanent PEC in my eq6r and predictive PEC in PHD2 cause a conflict?
Yes Predictive PEC would likely have trouble finding a periodic signal and behave weirdly - you should chose one or the other
Thank You, Cuiv. Little Pearls like this make life better. I'd say after the multi-Star guiding, this can really help automate the guiding process. A friend of mine gave multi-star out as soon as PHD2 allowed it to be given. He was a part of the Beta team helping to work out the release. I do have a question though, why do you have your settings so broad where you show Plus/Minus of 30°? I try to run my graph much, much lower so my graph is choppier. Mainly just curious, because I've observed this a lot when folks start demonstrating their graph's. Or is it to get a much broader view of time? Love your tutorials! I've already applied this to my "Mount Computer" that I use outside. (I remote operate most of the time. I'm old, and the cold bothers me.) Again, Thank You!
You referring to the guide graph scale in PHD2LogViewer? I think the scale defaulted to that when I opened it - also I don't want to scale it too much because then I might start getting obsessed with the guide performance!
Ah maybe my guiding will be more stable. I can get into the low .40's arcsec/pix, but then out of nowhere it goes to over 1.0 arcsec/pix. Very frustrating. I'm always watching it.
Good luck!
Thank You. Very objective for a beguinner like me. Clear skies.
Glad it was helpful!
Didn't know about that one Cuiv!. Thanks for that, I will definitely be giving it a go next clear night. I do have sine wave discrepancies on my guiding for sure.
Hope it helps!
Great tip Quiv, didn't know that so have to try this out if I can get some clear skies here in Belgium.
Question though, your title says "not multi stars" but in the video you write to enable multi star guiding ?
Just means that the trick isn't "multi-star", but something else (e.g. Predictive PEC). Basically clickbait :p
Great tip, I will try this, thanks
Gold dust Thanks Cuiv
Is there a list somewhere of your current kit ? Does the choice of guiding scope matter much in Tokyo ?
In my latest video :) Guide scope normally doesn't matter much in Tokyo (because terrible seeing) as long as it's well paired with the FL of your main scope...
So how does it interfere with GS server alternative checkbox?
Good question, to which I don't have the answer :-)
Amazing. I’m petitioning ZWO to get this on the ASIAir!
That would be awesome indeed! Although it won't help their own AM5 mount
0.51 RMS total is a great result. Thanks for going over this.
Thank you!
Did you give up on Antlia ALP-T? I just got mine and can't wait to give it a go
Didn't give up on it - but it's just not a good match to a hyperstar setup!
thank you, very valuable information!
My pleasure :-)
Cuiv, do you happen to know if there are PhD2 log files in the ASIair app that can be viewed on the PhD2 viewer? I would like to be able to view my periodic error, but I just recently switched from using Ascom and third-party software like APT and N.I.N.A to using ZWO’s ecosystem. Currently my total RMS error is between 0.6”-0.8” on my AVX mount using the “lite” PhD2 guiding within ASIair. I suppose if anything I can always still connect my AVX to the “other system“ to do the PhD2 log file but I’m getting spoiled with the ASIair. Like most of the other nerds and engineers watching your videos I appreciate your time explaining new topics like the way you do.
Unfortunately that's one of the limitations of the AA ecosystem - there's much less information to troubleshoot issues...
Cuiv, I just checked my images on my last session and there is a log file for the PHD2 output. It works with the PHD2 log viewer that you mentioned. When you transfer your image files from the thumb drive there is a log folder that has the log files in them. Just for all your viewers to know for sure you can still use the log viewer to see your performance of the mount with the ASIAIR.
Hi Cuiv, your video is interesting but but I think you have misinterpreted the results. RA error is roughly proportional to cos(Dec) and if you compare your mount performance at different declination you will measure different errors. So, if your error at the equator is 1" at 60 degrees it would be 1" * cos(60) = 0.5" so applying this equation to California nebula (dec = +36 degrees) and Heart nebula (dec = +61 degrees) we get cos(36) = 0.81 and cos(61) = 0.48, and this makes 0.81/0.48 = 0.59, which means about 40% improvement, which is pretty much in line with your claim of 30% improvement with PPEC on. I have a paper on that and if you want I can share it. So, I am not sure the improvement comes from the PPEC, but I am pretty sure it mostly comes from the tracking on a higher declination. I would advise you to repeat the test at the same declination with and without PPEC, with same settings (guiding exposure, aggressiveness etc) and then draw any conclusions.
I'd like to see that paper! I can understand why the error in pixel (for RA guiding) would be proportional to cos(dec), but arcangle (and guide pulse lengths required for corrections) should be unchanged. As far as I can tell the only thing changing would be the precision of the deviation measurements that gets worse the closer to the Celestial pole since the same arcangle of deviation would cover fewer pixels. And of course the impact on the final image of the same guiding performance would be diminished then.
To be sure I tested PredictivePEC and Hysteresis just now staying on the California and then the Heart Nebula, and I could reproduce my previous results on both (guiding perf sensibly the same between the two targets, PredictivePEC sensibly better than Hysteresis on both)
@@CuivTheLazyGeek Looks like if I put the link UA-cam refuses to publish my post. I will send the paper on FB. But generally, i do not claim PPEC does not help I just say that there may be another explanation. And I do understand your confusion. The difference in arcsec comes from the fact that the mount has certain error in RA axis. And the further to the pole you go the smaller its projection as the circle followed by RA is smaller. The guiding error is always measured on a great circle while RA error projection will be 1:1 only on the equator (on a great circle). While declination always follows a great circle.
I have the same thing on cem26 :) thanks for the trick :)
Excellent!
how do you know the period of the worm? I own an Eq5 but idk what is the period of its worms
Should be somewhere in the mount specs, or Google it! A lot of SW mounts have an 8 minute period
RA errors are proportional to cos(Dec). Dec of the California nebula is 36 degrees, and Dec of the Heart nebula is 61 degrees. Therefore, the ratio of the two RA errors would be cos(61)/cos(36) = 0.60. From the guide logs, the ratios were 0.37/0.61 = 0.61. So it seems to me that there was no difference in guiding performance between the two session, if you take the declination of the targets into account.
This has been pointed out before - I've done the test again on the same target and seen the same improvement!
@@CuivTheLazyGeek Interesting. Do you have an explanation of what has changed?
Cuiv, there is nothing lazy about the depth of what you’re sharing and for the engineer audience you can’t say too much! Now i have to wait for the next clear night to give this a try. Thank you!
Hope it works out well for you!
On my mount, EQ6.R, this sinusoidal periodic error is MUCH MORE pronounced. Why is that? I don't see it being this bad for anyone else, is my mount extra poorly made?
Could be simply a units problem, make sure to compare arcseconds to arcseconds!
@@CuivTheLazyGeek I have made sure of not making that mistake. I do also believe I have the guide scope focal lenght and guide camera pixel size set correctly.
I does not just feel like a difference in the amplitude of the sine wave., so many abrupt jumps on the guide graph. I have heard from others for whom PHD2 was able to remove most of the PE, without any PEC. Adding PEC only made marginal improvements for them.
Also, my DEC is quite bad, around 0.80''. Ra is at about 0.9''. Which gives about 1.22''. There are several 4'' peaks in both axes. Many 2-3'' jumps between two consecutive frames. I mean that's not really horrible I guess, but worse than what I had expected from roaming the internet. So, there could be other issues that is making the graphs look bad. Hardware, software and so on. Or I am expecting to much. Or it could that there is consistently bad seeing here in Sweden. Or my expectations are too high.
Thanks
Wow thanks for the support Andrzej!!
@@CuivTheLazyGeek you do a great work mate, lots of people moved forward with your guidance. So did I. Thanks.
Why not use predictive algorithm in dec? You only use predictive in ra?
RA axis only moves forward (or at most pauses) to adjust its movement, while Dec with perfect polar alignment should in theory be completely static. In practice it goes back and forth as needed - predictive PEC therefore doesn't make sense for Dec!
@@CuivTheLazyGeek ty very much :)
Nice video as always. I looked for the optional algorithns in the settings and the pull down menu was inactive (greyed out if you will). Is this s version thing or is there another stting that inhibits this? Also, do you have the PEC playback (I have an AVX mount) active when you guide like this?
Did you try while it was guiding? Also PEC playback should be disabled if using that algorithm!
@@CuivTheLazyGeek Thank you. It was guiding. I just looked at it when unconnected and the menu option is there. Somethings seam more obvious in daylight. As soon as the weather cooperates I will disable PEC playback and give is a shot,
With this, does that mean i should disable/clear all other PECs (EQMOD PEC, AutoPEC, etc)?
Correct!
@@CuivTheLazyGeek thanks, can't wait to try this!
Great information. Thanks for sharing.
My pleasure!
Hello Cuiv, thank you for this video. Unfortunately I cant read anything of your recording because UA-cam wants money from me to buy premium to get 1080p otherwise I only can stream 360p which is, for a channel about visual stuff, not useful. Maybe you can zoom in to the interesting points or read the values of your screen next time.
That's 100% a UA-cam bug - it should provide the 1080p normal option, and as far as I can tell only this video is affected. For now, I've used the UA-cam Studio editor to add a random blur in one second of a video. This should force UA-cam to reprocess the video, and maybe fix the issue.
And it seems that worked!
@@CuivTheLazyGeek Thank you very much, you're the best! Is see clearly now, the blur is gone. You are a human BlurXterminator :) BTW ontopic: yout Trick worked great!
Many thanks!
All I can say is thank you thank you thank you!!!
My pleasure :-)
You sir, are a scholar and gentleman!
Thanks Vipin!
Didn't know this, good to know. Also set your guidecamera to 16bit.
Ooh, I need to check that too!
@@CuivTheLazyGeek you do it where you connect the camera
Great work putting this out there Cuiv! - I'll be giving it a go for sure! :-D
Clear skies!
Thanks Luke! I'll be curious how well it works out for you!
In the photography world we have a lot of cameras with image shake reduction hardware that the sensor is attached to. Seems to me this would be an excellent way to tackle some of these areas - basically in camera. Perhaps this is not really a good solution or the market is not pressuring the manufactures to build it.
That's exactly what Pentax Astrotracer is ;) And Olympus' derotator patent. Would be great to have physical optical stabilization on astrocameras so guiding corrections could be done in camera but the range is small and there's a whole cooling element stuck to the sensors backside!
@@CuivTheLazyGeek I was aware of Pentax's feature, but not Olympus. I forgot about the cooling problem - I suspect if the motivation is there it could be solved. Which leads me to ask - just how big of a range would one need (assuming a reasonably good mount).
What a great guy! Thanks for still MORE helpful information I can put to work easily and quickly. And I’ll even sort of understand what I’m doing!
Absolutely amazing to have to you back mate! Just learned something new from you (again)… Will implement this as some as weather improves here in Melbourne … now I have to remind myself how to turn off PEC corrections from my mount - EQMOD😂
Thank you, Cuiv.
I will certainly give this a shot.
Fantastic video!! Honestly this has been very useful and I look forward to seeing if I can improve my guiding with this method… however I use ASiair plus, do you know if the ASiair has this setting? I’ve not noticed in the settings, but I do notice a similar wave pattern on my guiding… I use an EQ3 pro mount. Thanks
I don't believe it's in the AA yet - you may want to petition ZWO to get it added ;)
@@CuivTheLazyGeek ah ok thanks Cuiv, I think I may have to try PHD2 guiding by itself in one of my next few sessions. My guiding has improved a lot recently by carrying out PA at least twice and making sure that I calibrate the guider everytime. But I do still notice the wave pattern. I could never figure out what could be happening so I’d try adjusting the aggression but ultimately because the guiding is usually around 0.7 arc seconds I haven’t been too troubled. But a fantastic video that really makes you realise there is much more to many aspects of AP than you would at first think. I never considered impurities in the worm and I do have one of the cheaper mounts too haha
@@Astroephotography see my reply to Cuiv, you Can access PHD2 log files in ASIair…
I will definitely try this the next time I image. Guiding can be such a mystery at times, the last two months I was really frustrated I went from an average of error of 0.7 to 1.0 to 1.5, last time I imaged it was back down to 0.6 the difference being the seeing conditions were really good, prior to that they were not. I don't suppose this would have much affect when seeing conditions are poor?
With really bad seeing it would be less effective, although since it's looking for Fourier frequencies, it should still make a difference by properly recognizing periodicity
Seeing and relative humidity are huge factors. My summers are quite humid and my normal RMS shoots up by 0.30 easily. Dry winters nights are much easier to guide.
Thanks a lot!!
I use to have to record my pec in the beginning of all of my sessions and loose about 16 minutes ...
I can't wait to try this 👍👍
This video dropped just in time! I literally looked up which PHD2 algorithms were better to use a couple of days ago and ended up settling for PPEC, which was one of the most recommended. Glad to know how that works now :)
Keep up the fantastic work. Absolutely great video. Demystified some things for me! Gave me confidence to delve into the guts of PHD2.
Cuiv, very well done explanation of cause and effect. This was done so well, I would suggest you consider doing slightly expanded version some Sunday on The Astro Imaging Channel (TAIC). They are always looking for great presentations.
We love your videos….and you too.
I'm going to blush there Jane :😁
Thanks for that Cuiv, I will give it a go next session. Pete.
On my Skywatcher HEQ5 mount which definitely exhibits PE in RA. I generally get good enough guiding total RMS around 1 arc sec but also annoying “random” excursions in RA up to +/- 4 arcsecs which does seriously affect my images. Pete.
Hope it fixes your issues, good luck!
So great to have you back to making astrophotography videos again, Cuiv! I've always learned so much from you and this video is no different. I will be giving this a go next imaging session. Thanks for all of your help and tips over the past couple years. Take care, Cuiv.