[DiscoDuck (Paul)]

Originally Posted by ChrisV

I'm no expert but I've seen periodic spiking when I've used the backlash compensation.

Thanks Chris. I think (may be wrong ) that backlash compensation only affects dec guiding. In any case, I've been using that for quite a while without issue and this problem only surfaced in the last couple of weeks.

Originally Posted by alpal

Hi Paul,
would my experience help you?

here:

https://www.flickr.com/photos/24719437@N03/6001169049

Thanks. I agree the bar is rubbish! Don't know why they couldn't do a better job. In my case, I don't think it was the cause of this particular problem as it was in a stable position and not moving. But definitely worth my looking at. Thanks again.

Originally Posted by Russj

G'day Paul, I have a NEQ6 which had graph similar to yours but was perhaps a little more spiky, although I could still image at 10 mins subs with round stars,...... go figure . I eventually got my rms down to .6 (on a good night) by the following.

1. I hypertuned the mount, (didnt replace any bearing).
2. fitted a Rowan belt kit
3. Run PEC in EQmod
4. Run Predictive pec in PHD2

My mount works well now, rms will still move over 1 on a poor seeing night which is to be expected.

I used to look at some of the almost perfect graphs on other forums and wondered how they do it on cheaper unmodified mounts in light polluted cities, something did not ring true to me, the reason I mention this is because I went down this road, spent a lot of unecessary time trying to get a near perfect graph, which I stil am unable to achieve, my graph still spikes a bit but I've got tight round stars, thats all that counts in the final washup.

These links may help, https://groups.google.com/forum/?fro...en-phd-guiding
http://www.astro-baby.com/EQ6%20rebu...own%20Home.htm

If I can help with any of the above let know

Hope this helps Russ

Thanks Russ. Much appreciated. I've already got a belt kit in there and had a re-grease at the same time. That was about 2 years ago, so it may be in need of a refresh/retune. I'll chase that up.

I've played with PEC before in EQMod. Never tried PHDs one. Can that work together with the EQMod one or do they interfere?

Re stars, yes, they were not as bad as the guide RMS would suggest, but the frustration is I've had much better up until now, i.e. RMS usually no worse than 0.5" RMS.

Thanks again for the advice. I'll look into the re-grease/re-tune etc. And again very much appreciated.

Originally Posted by Imme

Couldn't agree more with that last paragraph......there are probably 300,000 or more mounts out there in the world, the best 50 guide graphs get posted as 'this is how good my guiding is' and then we all try to compare ours to that.

As long as you stars are round then the guiding is perfect in my opinion!

Well, round and small is even better

Originally Posted by Atmos

Something else that might be worthwhile is stripping your mount down and giving it a regrease. For a time I had some guiding issues (random 2” spikes) that started appearing. After a regrease they went away. You just have to remember how tiny a particle needs to be for it to show up in the tracking

Thanks Colin. Sounds like it's time to pull out the lithium grease!