Skipper Billy Posted September 3, 2016 Share Posted September 3, 2016 I recently bought the QHY Polemaster setup as I find the drift routine in PHD2 a bit tedious. They give different results !!! The error is repeatable too - I can set up with Polemaster and then drift align in PHD2 and it requires a half turn clockwise of the altitude bolt to get the drift right - back to Polemaster it needs half a turn back anticlockwise to get the crosses lined up - I can repeat this ad infinitum. So which one is right ??!!! Stars are round with either setting but the guiding seems to have less work to do when drift aligned in PHD2 than with Polemaster. This is in an observatory so tripod movement etc can be ruled out. Any ideas ?? Link to comment Share on other sites More sharing options...
michael8554 Posted September 4, 2016 Share Posted September 4, 2016 Only one way to find out. Leave the scope drifting for 10 minutes, on each setting, with a reticle eyepiece, and see which one drifts out the most. Michael Link to comment Share on other sites More sharing options...
StuartJPP Posted September 4, 2016 Share Posted September 4, 2016 I would suspect that the drift aligned one is the more accurate one...but that is only my opinion. It would be kind of you to let us know which it is... Link to comment Share on other sites More sharing options...
Skipper Billy Posted September 4, 2016 Author Share Posted September 4, 2016 I will try the above suggestion and report back. Link to comment Share on other sites More sharing options...
Jannis Posted October 17, 2016 Share Posted October 17, 2016 Were you able to find out which of them was correct? And, how much difference is there actually? From what I've heard the polemaster can quickly achieve more accurate polar alignment then most others have been able to before, but for a permanent setup i would also assume a long and time-consuming drift align would be the most accurate. Link to comment Share on other sites More sharing options...
alacant Posted October 18, 2016 Share Posted October 18, 2016 On 4/9/2016 at 14:53, StuartJPP said: drift aligned one is the more accurate Hi. +1. Also PHD2 is never wrong. Link to comment Share on other sites More sharing options...
KyleStoke Posted October 18, 2016 Share Posted October 18, 2016 I used the polemaster for the first time a few weeks back checked the results with PHD2 and it gave me an error of 10+ arc minuets i ignored this and got round stars on 15 min subs. Could be whatever settings are in PHD are incorrect, giving a false result. Link to comment Share on other sites More sharing options...
Tiny Small Posted October 18, 2016 Share Posted October 18, 2016 I've found that PHD is very inaccurate with it's drift align. I did an actual drift align using DARV and got a straight line on both axes at 10 minute subs. I can image unguided for a number of minutes with no trailing and on 900 second subs, no rotation, so I know it's decent. PHD reports it as substantially out and the guiding assistant recommends 4s subs. With this alignment, I am consistently drifting within +-0.5" with RMS errors ranging from about 0.08 to 0.14 in each axis and a total of under 0.2 usually. Until a gust catches the scope or something then I might get a spike of 1". So I wouldn't trust the PHD drift align that much. Link to comment Share on other sites More sharing options...
lukebl Posted October 19, 2016 Share Posted October 19, 2016 Can I throw Sharpcap's polar alignment into the mix? It's free and seems very quick and effective. Then you can compare the best of three! Link to comment Share on other sites More sharing options...
Ken82 Posted October 19, 2016 Share Posted October 19, 2016 Just remember if your mount has a large amount of uncorrected periodic error it will affect your drift alignment results . Link to comment Share on other sites More sharing options...
emyliano2000 Posted December 9, 2017 Share Posted December 9, 2017 Sorry to bring back this thread but last night I aligned perfectly with my polemaster and the error in phd2 was huge. What alignment method gives you better result in the end? Emil Link to comment Share on other sites More sharing options...
swag72 Posted December 9, 2017 Share Posted December 9, 2017 1 hour ago, emyliano2000 said: Sorry to bring back this thread but last night I aligned perfectly with my polemaster and the error in phd2 was huge. What alignment method gives you better result in the end? Emil Interesting......I found the Polemaster gave me a pretty poor PA on my mount when checked in PHD2 Link to comment Share on other sites More sharing options...
emyliano2000 Posted December 9, 2017 Share Posted December 9, 2017 The problem is that my visibility is quite restricted up to 25 degrees above horizon to the east and the west so I can't go close to the horizon. It's the first time I had a go at phd2 and I really wasn't expecting such a huge error. So far I've been using the lacerta standalone autoguider. I think I did the polemester alignment better than I ever did. I would also like to add that my mount has been hypertuned. Link to comment Share on other sites More sharing options...
Davey-T Posted December 9, 2017 Share Posted December 9, 2017 You can drift align on pretty much any star, the further from the pole the faster the drift will be which is the reason for using the horizon but then the nearer the horizon the more the atmospheric dispersion, you need to get the "crosshairs " at right angles to RA /Dec movement and as mentioned if it takes too long to reach a conclusion mechanical issues will interfere with the results. Best not to get too OCD about PA if it's near enough then guiding should sort it, you may get a bit of field rotation but stacking should sort that. Drift aligning using an illuminated graduated reticle eyepiece is good on a permanent setup but not worth messing about with every time on a mobile setup, time is better spent gathering data rather than wasting time drift aligning. The DARV method is pretty good in terms of results vis time taken, not used Polemaster but is seems an expensive sledge hammer to crack a nut, just my opinion may be talking rubbish and not for the first time Dave Link to comment Share on other sites More sharing options...
emyliano2000 Posted December 9, 2017 Share Posted December 9, 2017 12 minutes ago, Davey-T said: The DARV method is pretty good in terms of results vis time taken I will try DARV next time to see how the drift is. I want to use phd to see the errors in the mount. Link to comment Share on other sites More sharing options...
Davey-T Posted December 9, 2017 Share Posted December 9, 2017 1 minute ago, emyliano2000 said: I will try DARV next time to see how the drift is. I want to use phd to see the errors in the mount. I'd hope a hypertuned EQ6 would have no problems imaging guided when PAd within 30arc secs, why do you want to see the errors in the mount ? Dave Link to comment Share on other sites More sharing options...
emyliano2000 Posted December 9, 2017 Share Posted December 9, 2017 8 hours ago, Davey-T said: why do you want to see the errors in the mount ? The mount is 12 years old and I'm just curious to see if I can get to 10-15min unguided with my lightest setup ( ts65 quad + dslr + OAG + QHY5). ? Link to comment Share on other sites More sharing options...
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