Setting up procedure+guiding PHD2

[david_taurus83]

Morning everybody. Hopefully the more experienced folk on here can offer some advice. Last night we had clear skies here in the Midlands so was my first proper attempt at guiding. My tripod is left out in the same place and is bang on level so when I bring the mount out (EQ5) and set it up its pretty much pointing towards Polaris. I've recently attached another dovetail on top of the clamps of my 200p and bolted on a ZWO finder scope with guide camera. I collimated main scope from outside last night, pointed at the moon and made sure both scopes were pointing in the same direction and returned to approx home position. So far so good! Not a cloud in sight! Fired up Sharpcap and using the guide scope to do the polar align. Got it down to excellent and repeated by returning to home and rotating the RA to the opposite side as the first time. First result came back as fair by about 3 minutes. I thought maybe I've got some cone error somewhere but not enough to affect guiding. So done a 3 star alignment with the hand controller and got a error of about 30 minutes. So I left it at that and then switched over to EQMOD on the laptop. That's when the fun began. After faffing about for ages with PHD crashing everytime I connected the ZWO camera and switching cables around on the USB hub, it then struggled to calibrate. It kept saying the star didn't move enough. It kept saying backlash couldn't be cleared. It gave an error message a few times saying Ascom pulse guiding signals stopped being sent to the mount but it remained guiding? I was using stellarium scope and the scope position on screen was nowhere near where the scope itself was pointing. Eventually it calibrated with a 30 degree error! Despite all this I still managed to get some usable images of M45. I will load into DSS later and let it sort them out. I switched to carte du ciel late on and attempted to drift align. Calibration this time was pretty straightforward but the results were still poor but I managed to get both axis down to below 1 minute error when the battery on the Canon camera died and upset the USB hub and crashed everything!

 

So points to be taken from the above debacle:

1. I appear to have some alignment issues between main scope and guide scope as I would expect Sharpcap to be more accurate with it's polar align feature.

2. When I do a star alignment on the Synscan controller, any error is compensated for if continuing to use the hand controller. When I switch to EQMOD, are those errors not seen and EQMOD assumes good polar alignment and starting from the home position? Hence the wrong scope position displayed on Stellarium and Carte du Ciel? In Ascom I can put in fairly accurate location coords but on the Synscan controller I can only put in to the nearest minute. Is this an issue when trying to start off with a good home position?

 

3. Moving forward, would a sensible approach at this time be to not use Sharpcap initially until I sort out any cone error/scope alignment issues? Set up as normal, do a 3 star alignment, return to home position, switch to EQMOD, drift align using PHD2, return to home and repeat another 3 star alignment to get a better home position and position displayed in Carte th Ciel should be more accurate?

 

I would have to do this every time as it's a set up from scratch so I'm interested to know how anyone else has to set up from scratch all the time. Is there a more efficient method or is this one of the joys of Astrophotography?!

 

Thanks

 

David

[ChrisEll]

I think nailing SharpCap is a priority. Be sure to move onto the "next screen" before turning the altaz knobs (this still catches me out). Once I've twiddled with the knobs and got it to near zero I always repeat the process to make sure it's still zero. +/- 10" is good enough. I've had problems with the later versions of SharpCap and my QHY camera and had to go back to version 2.9.

In PHD2 always visit the Calibration Calculator to determine the correct step size before calibration. Check the pixel size of your guide cam and FL of your guidescope are correctly entered.

I believe there's a tool called ConeSharp, also on the SharpCap website.

[spillage]

I would not bother doing an alignment. You are using a canon so thats a plus.

Download APT (its free)

Connect your mount to the pc, I take it you do not have an eqdir cable only via the hand set in pc mode.

Open up phd2 and connect the mount and guide cam.

Run drift align.

open up apt connect camera and scope/mount. Under mount click platesolve and choose M45 from the list then goto++ once you have success then click sync.

when you open cdc and connect to the mount it should show the correct position.

 

Sorry thiis is off the top off my head so may be a little wrong in places.

[bottletopburly]

If the clouds didn’t roll in then you can’t be far off getting it right lols ? 

[alacant]

1 hour ago, david_taurus83 said:

would a sensible approach at this time be to not use Sharpcap

Hi. Yes. PHD2 has three methods for polar aligning built in. One of them very similar to the sharpcap method.

Here's another way to get up and running efficiently:

1. Put the mount home using using a bubble level on the RA and DEC axes

2. Lose sharpcap

3. Lose the star alignment via the hand controller

4. Connect eqmod

5. Connect cdc

6. Slew to Capella

7. Centre it in the FOV

8. Focus the imaging camera

9. Sync cdc to capella

10. Slew to -near- the equator-meridian intersection. As @spillage has recommended, APT will simplify this significantly by eliminating steps 6, 7 and 9.

11. Connect phd

12. calibrate

13. drift

14. guide

HTH and good luck.

[Thalestris24]

Hi

Do make sure everything is balanced in all 3 axes at the start. Polar alignment, especially drift alignment with PHD2, is a bit chicken and egg. In order to calibrate PHD2 you need to be already fairly close with PA but you need to calibrate before you drift align, so it can all take a few iterations. If you have any problems with calibration or drift aligning, it's a good idea to run the PHD2 guiding assistant.

Louise

[david_taurus83]

Thanks for the replies. I look forward to trying a different approach in 3 or 4 weeks time with the next clear night!

[david_taurus83]

Well I had another go last night. Gave sharpcap a try again in case I messed it up the first time. On the second step I rotated RA to the East and got result down to excellent but if I repeat and swing to West I get a 6 minute error. This again is mirrored to the East side if I restart and get the West side to excellent. What could be causing this? Could it be the mount isn't level? The tripod is bang on but the bubble on the mount is off. I'm not sure if the mating faces on the bottom of the mount or too of tripod are true?

 

The above info about focusing on an a star and simply pressing Sync in CdC is great! Even with a bad polar align it wasn't far off when slewing to different parts of the sky.

 

So I ran PHD and calibration results were down to a 20 degree error this time. Started drift align and after a few minutes got azimuth down to under 1 minute. Great! Slew West to do altitude. And then the clouds roll in!! It kept losing the star! After 45 minutes of this I gave up so picked an area that was cloud free and ran Guiding Assistant. This took ages. It appears I have an issue with Dec backlash. Results below:

 

[spillage]

Its been a while since I have had my hands on the eq5 but with the eq5 pro I am sure you could move the motors to improve backlash. You should really wait until you can run drift align fully and then have another look.

[newbie alert]

You might have cone error within the guidescope when running sharpcap.. I use my polemaster camera with sharpcap and after adjusting after the 30 degree rotation I return to home and fine tune it..i think that there's a difference between sharpcap idea of perfect PA and phd,but never 20-30 arc mins..maybe 1- 2 (I've yet to do phd2 drift alignment)

[david_taurus83]

2 hours ago, newbie alert said:

You might have cone error within the guidescope when running sharpcap.. I use my polemaster camera with sharpcap and after adjusting after the 30 degree rotation I return to home and fine tune it..i think that there's a difference between sharpcap idea of perfect PA and phd,but never 20-30 arc mins..maybe 1- 2 (I've yet to do phd2 drift alignment)

Yes, possibly. The guide scope is definitely pointing in the same diretion as the main scope but clearly something is not right. The 22 arc minute error above is likely a result of an abandoned drift align. I adjusted the azimuth and then the clouds rolled in before I could tune the altitude. I ran Guiding Assistant after.

[david_taurus83]

4 hours ago, spillage said:

Its been a while since I have had my hands on the eq5 but with the eq5 pro I am sure you could move the motors to improve backlash. You should really wait until you can run drift align fully and then have another look.

I tried again this evening but alas, clouds again. I should add, my setup is slightly scope heavy. I know I'm way over the recommended load allowance for this mount but where I thought the RA would struggle as it's scope side heavy, this appears to be fine. It's the declination, which is well balanced, that struggles. In fact, there is slight play in the RA worm gear still but the declination has virtually nothing. I will strip the motor off tomorrow and check all again.

 

[david_taurus83]

Another update. So I think I've managed to reduce some of the backlash issues I was having. As spillage has said, the motors can be moved to reduce backlash. The Dec motor had quite a bit of play between the drive gear and the bigger one that contacts the mount gear. Maybe 0.5mm or a bit more. Doesn't sound like much but considering the drive gear is small it's a lot! I moved both Dec and RA motors closet to the gears anyway, not too tightly but enough to remove any free play by hand. After calibration last night I get the below result. Now I only aimed at Sirius with the finder scope so I'm not quite sure how accurate it was so my guess is it was a bit off as it's hard to tell exactly where your pointing in PHD. I'm guessing I still need to work on polar aligning before calibrating and drift aligning. Was hoping to start some guided imaging Friday night as Clear Outside is "promising" me a clear night. Instead I think I'll be messing about with Conesharp trying to get mount, 200p and guide scope all parallel and pointing in the same direction!

[alacant]

25 minutes ago, david_taurus83 said:

aimed at Sirius

Hi. That's quite low. You could try a bit higher; Orion's belt at around 23:00 would be ideal.

27 minutes ago, david_taurus83 said:

mount, 200p and guide scope all parallel and pointing in the same direction

Don't go too obsessed. So long as they're reasonably close, PHD2 doesn't mind. It looks like the outward calibration -when the gears are meshed- went very well. A nice right angle. Then the return journey, not so well due to the backlash, but it doesn't matter about the return journey as by then the calibration has been done.

Did you try guiding? I think you may have been pleasantly surprised. Remember to look at the images you produce rather than the graphs. HTH and good luck.

[kens]

It looks like your PA is affecting the calibration. Thats just a guess and it would be helpful to see the guide log. 

Make sure you run the guiding assistant on the tools menu and follow its recommendations.

If you are game to try the snapshot version of PHD2 (its quite safe really) you could try the Polar Drift tool which is remarkably simple to use and does not require a good calibration to work. It's useful to get you to within about 10 arcminutes after which you can calibrate then switch to any of the other tools available to get closer. 5 arc minutes is good enough for jazz. 

 

[david_taurus83]

^^Hi yes, tried guiding but...clouds? It started off ok but then the RA started to peak so I had to mess about with the aggression to bring it back down. Tried to run the assistant again also but it couldn't complete because of the clouds. I should add I also got the drift align down to within a minute or so on each side but as I dont think I was pointing where the mount thinks it was I think this may have an overall effect on everything as well. I'm going to try and iron out any cone error/alignment issues as I think this is affecting Sharpcap. I tried that also but the centre of rotation is way off screen. I'm pleased though that it's an improvement on before. If I can improve something on each attempt I'll be very happy. The main frustration is the lack of clear skies to get stuff done whilst also clock watching knowing I have to get up at 6am for work!

[spillage]

That new calibration looks good to me. I would run phd drift align and make sure you allow it to run for at least 5-10 minutes in azi and alt. Don't get too hung up on it though.

You can then experiment with exposure times. 

As much as it pains me, I do every nown and then give up a clear night just for things like polar alignment and tweeking bits of kit.

 

Late posting so missed your reply.

Get everything connected and unpark the mount. Using apt take a short single shot and platesolve, then use these results to sync the mount.

Then just use phd drift align and slew to the recommend co-ordinations. If you have issues with your view then just make adjustments until you have a star in your fov to use.

Rember to keep slewing the mount back to the correct postion to keep it as accurate as possible.

You may not need to plate solve but that just the routine I have.

[david_taurus83]

Success!

 

Well, sort of. Friday night did indeed give me that clear night so i set to work. Drama straight away. PHD couldnt even calibrate this time. Refusing to waste another clear night i ticked the box to restore previous calibration, restarted and just set it to drift align anyway. Took me ages to get each axis down to below 1-2 minute error but I got there and set it guiding.

 

 

So onto guiding. Started off ok and then the dec line started to skyrocket! About to throw in the towel and just get some image time without PHD I remember reading somewhere on the forum that some folk change the AUTO tab on the dec axis to guide in one direction only. I changed to South and within a few minutes the graph flatlined! I left it for about 10 minutes and it stayed the same.

 

 

 

The above was taken at the end of the session. I managed 60 usable 120 second subs on M81. I even took a 5 minute sub at the end to see if my setup is capable and there was zero star trail whatsoever. So maybe up the exposure length next time. Still though, I've ordered a Polemaster (and a Baader coma corrector) as I just havent got the time to mess about so much before I can start imaging, with work, a young family and the weather I want to make use of every available chance I get!

 

Thanks for all the input above as it certainly helped. I couldnt get APT to plate solve though, despite downloading the various add ons needed. Something to investigate further I suppose. For now, I'm happy to have got off to a successful start.

 

 

^60 no. 120s subs ISO800 Canon 600D Modified Baader BCF1 filter + Skytech CLS CCD clip filter

 30 no. darks, flats and bias. All pre and post produced in Pixinsight using begginers workflow tutorials on Youtube.

 

David : )