I've noticed I have a small amount of drift with the tracking of my EQ6 and I've put up with it so far as it didn't really bother me, but as I've been experimenting with imaging more recently it's become more of an irritation.
I've timed the drift of a planet across the FOV of my planetary camera and by my calculations the object drifts off by about 1' per minute.
Given this is a popular mount and lots of people use them for imaging, I was hoping you helpful folk out there would be able to give me some tips as to where I should start adjusting the mount to reduce this, with the objective of being able to keep a planetary object in the FOV for longer, and to allow me to take longer exposures of DSOs.
I've recently performed a belt mod on the mount and the drift is more or less the same as before. It also seems to do it more or less the same regardless of which scope I'm using with it, but is more obvious at higher magnifications...when I've been imaging Mars at f/25, it just about stays in the FOV long enough to capture a video sequence
It might be worth your time to download Synscan version 3.35 - as that contains a polar alignment checking and adjusting routine. You can also use PAE to adjust for precision in the area of the sky your working. I assume your not using a guidescope.
Another consideration is that Planets traverse the sky at different rates/speeds to each other and with the stars, I would watch a star in the field to see if the resulting effect of 'drift' are the same as your experiencing with the planets ?
My 1st thought was Polar allignment, but I would check out a stars behaviour 1st !
Hi Dunk, Bob and Glen are both right.
Start by downloading and installing version 3.35 to your hand controller.
Use the polar align function therein. Try to get down to a few arc seconds.
Download and print out the complete manual for the hand controller.
It's about 45 pages. A 65cent plastic binder thingy will make it into a
convenient reference booklet [A4 size]. Lots of info in it.
There is no planetary tracking speed for the reasons stated by Bob, but
if your P.A. is good, the planet should drift slowly enough for you to get
a decent video. The tracking difference between planets and stars is actually very small, so checking your drift with a star [as Bob suggested]
is a good idea. If it is pretty much the same[as it should be], then your
P.A. is not good enough. If I put Saturn at the centre of a prime focus field in my 8" f/5, it is still in the field an hour or more later.
raymo
The weather is threatening to be clear tomorrow night so I will try and give it a go. I'm already running 3.35 and as I've been polar aligning by eye to less than 1 degree of error in either axis I've not been using the polar alignment routine. I'm not guiding, so I guess I'm introducing the error by not aligning well enough
Will try on a star ASAP and see what happens... with my planetary camera and powermate I'm basically running at about 1000x, so the effect is amplified but my DSO images have showed trails too. I need to practice drift alignment too...
I'm guessing you're aligning on Sigma Octantis? 1 degree PA isn't going to cut it for the focal length you're working at.
Don't know how well you'll go, but try to get dark adapted and use averted vision to align on mag6.8 BQ Oct. This will get you just inside of 11 arc minutes from the SCP.
I'm fortunate enough in light polluted suburbia to be able to also just make out mag7.8 HD99685, which with BQ Oct. almost forms a Right triangle with the SCP at the Right angle. With dark adaption and averted vision and some time adjusting, this gets me to within around 5 arc mins.
You're probably not going to be able to see HD99685 from Sydney tho, but worth giving BQ Oct a try.
Thanks chaps, I don't have a view of the SCP from here, big tree in the way so will probably have to rely on the polar alignment routine until I can get to a dark site again
I should be able to see BQ Oct through the finder scope though right? Or would I be better putting a small refractor on the mount for the PA?
Hi again Dunk. You don't need more than one way of doing P.A.
The P.A. routine in Synscan will get you just as close as the polarscope will, with a lot less neck cricking. It is a bit fiddly at first, but once you
know how much to turn the knobs for a given result, it's pretty
painless, and doesn't take too long.
raymo
If you can, it helps to mark the ground where your setting up. I have a bright brickie's string pegged to the ground to show exactly the line for True South, and my tripod feet go on exactly the same spot each time. If you sit the south leading foot on the string line then the othe two feet must be equal distance from the string line, you will be very close then. BTW, If you have not done so, you can move the square peg sticking up on the mount base so that it sits right behind a south leg, mine came from the supplier set up for a north leading leg and I suspect they all do. Having a south leading leg helps with setup alignment.
Raymo is right, just forget about trying to see anything around the SCP and use the PA routine in Synscan V3.35. With my string line I am usually within seconds of the SCP on azimuth. And forget about using the Altitude pointer on the scope, it is never accurate (mine is off 4 degrees), must be a mashocist that puts them on the scope. Get an inclinement off ebay and put it on the mount dovetail when your setting up the Altitude (don't forget to align the inclinemeter to level before you start). Good luck
Judging by the comments here it might be worth my while trying 3.35.
I tried 3.32, 3.33 and 3.34 and they were all buggy(well documented here and on other forums) and i reverted to 3.27 in each case, which is where it remains, but sounds like they finaly got it working in 3.35 huh?
If the PA routine can get me within the claimed few seconds, I might just try it
Thanks chaps! I try to escape the light pollution when I can, so I have to learn how to get it right quicker...just practice I guess. Only then will I be able to tell if there's something more wrong with my mount, besides me touching it
Judging by the comments here it might be worth my while trying 3.35.
Plenty of people have had issues with v3.35, including me, but also plenty of people haven't. I don't know why some people experience issues and others don't. I'm back on v3.27, which still works well for me.
From my point of view, v3.35 firmware might be worthwhile if it did something useful with the Mel and Maz error measurements that it makes ... like tracking in DEC, for instance. Alas, it doesn't.
As for Dunk's problem, that's clearly a polar alignment issue. With good polar alignment (however achieved) you should look forward to very little drift of planets at the eyepiece: I can often go 30 minutes without needing to touch the SynScan arrow buttons on my NEQ6 Pro. I've even had Mars at 12.5 metres focal length stay centred on a camera sensor for 15 minutes ... and that was just using the polar scope.
Plenty of people have had issues with v3.35, including me, but also plenty of people haven't. I don't know why some people experience issues and others don't. I'm back on v3.27, which still works well for me.
Hmmm ok thanks.
I'll try it, but I'll probably be back on 3.27 and visual PA.
Sorry to hear that you're having drift woes! I'm not familiar with your specific setup or workflow, so I can only really tell you what has worked for me.
My EQ6 came with SynScan hand controller firmware 3.33, so I can't comment on any versions prior to that. If you've had drift-free sessions in the past, I would suggest updating/downgrading the hand controller and/or motor controller firmware only as a last resort. Personally, I feel inclined to go back to 3.33 since I find the new two-stage polar alignment procedure to be no more accurate than it was in 3.33 and if anything, more cumbersome.
As Astro_Bot pointed out, I agree that it's probably a polar alignment problem more than anything else. I'm very picky about polar alignment accuracy and not being able to resolve Octans from my location, I rely on the polar alignment routine in the hand controller.
What I've found works really well if you want a very accurate polar alignment, is to do both the 3-point mount alignment and polar alignment routines using a guiding camera with a high-speed readout (a modified webcam will do, though) and a barlow lens -- the higher power the better.
I use PHD 2 to see what's happening in the camera and, after enabling the on-screen crosshairs and adjusting the focus so that the star is bloated enough to fill the centre circle, bring it into the middle (see example image attached).
Once you've done both the 3-point and polar alignments using this method, you've got an excellent starting point for making adjustments to compensate for any drift as it's much easier to see the drift on-screen than it is through something like a 9mm illuminated reticle eyepiece.
I've been able to achieve =< .175" accuracy using this method.
If you want PHD 2 to show you how much error you have in your PA, you'll need to arrange an autoguiding setup first using a small refractor or an OAG. Then, in PHD, just turn off Dec guiding and it'll give you a readout on your PA error.
I suggest powering off the mount after doing the polar alignment and then going through both the 3-point and polar alignment routines again to confirm and refine. It can take a little while, but if you don't have a permanent setup and want the accuracy level, it's worth it.
Be mindful of the fact that if the mount is not sufficiently balanced (or if it's overloaded), it will impact the accuracy of your 3-point alignment, which in turn will impact the accuracy of the polar alignment routine in the hand controller.
Disabling the auxiliary encoder via the appropriate menu in the hand controller will improve pointing accuracy too, so you may like to give that a go if you've not done so already.
So...I've been out practicing with the polar alignment routine... after 3 rounds last night, Synscan reported Mel 21" and Maz 24". That was the best I could do. I found the altitude knobs especially difficult to operate with any accuracy getting this far. Alignment stars were Miaplacidus and Antares, and Antares was in the FOV of a 7mm eyepiece (about 290x in the C8).
With the scope parked, I added the reducer (0.7x, so about 1400mm F/L), rebalanced and took some test images with my 1100D and I've posted a stack of M22 in the Beginner's AP section. I was able to get 15s exposures without stretched stars. How much more should I able to eek out without resorting to guiding?
Be very careful with using the steps outlined on page 35 of the V3.35 Manual related to adjusting the Altitude during this PA routine. It is my view, with a scope on the mount, and it keeled over as it is at that point, that trying to adjust the Altitude may lead you to stripping the threads on the mount, especially if you have to go up. You should never use the Altitude knobs alone to move the mount - Andrews Comms carry a warning on their Skywatch page advising that those bolts are only for locking - not moving. I try to get the Altitude as close as I can using my inclinometer before the PA routine and then not touching it - unless it is out by more than 1' and it has to go down. The Azimuth is never a problem. I'd bet that most mount thread strips happen on that back hole where it forces the load upward.
I don't feel a lot of load on the front altitude adjustment bolt (the one that raises the mount against gravity), certainly not enough to strip threads. I'm guessing the stripped threads are the result of people trying to adjust the bolt without loosening the opposing one. I've seen pictures of bent azimuth bolts resulting from that very same kind of mistake.
I agree with the lack of precision when it comes to the last couple dozen arc seconds of PA error. The adjustment feels mushy and imprecise, probably because of steel bolts with irregular tips digging into cast aluminium. I'm planning on replacing the bolts with ball-tipped ones – if I can find some.
Drift on EQ6
so will probably have to rely on the polar alignment routine until I can get to a dark site again 
