RA Drive speed?

[Perkil8r]

Last night I set up the EQ5 with the st80 and DSLR. I set it up bang on the moon and set her running to see how far out my alignment was. What appeared to happen over the space of half an hour to an hour was the mount appeared to have moved too far in RA.

Is this because the moon moves at a different rate, therefore over half an hour to an hour I would notice this, or is it something that might be wrong or need adjusting?

I do know the mount wasn't aligned perfectly due to the polar scope being slightly out before, now being centred perfect, thus the mount wasn't quite aligned perfectly at this point. Once dark enough I did manage to polar align spot on, I would say DEC was almost perfect anyway but RA was Roughly 1 deg out, maybe 2. I wouldn't have thought this would be enough to produce the speed issue? Just to clarify, to get the moon centered again I only had to alter the RA, I didn't have to touch the DEC, and pretty much the same was true for the polar aligning.

Am I worrying about something that is correct, or am I worrying for the right reasons? Should I try a similar test with a star rtather than the moon? I set it up, and left alone completely, didn't look for between half to an hour or so, so it's not like it was enough to see movement in real time.

Hope some of that made sense?

[Tweedledee]

Lunar rate is slightly slower than sidereal rate, so it is nothing to do with the moon. Hopefully you just accidentally nudged it. You will just have to check again. Fingers crossed.

[Tweedledee]

Although if you were tracking at sidereal rate the moon would appear to lag behind a little. Maybe that is what made you think the RA went too far.

[+Graham]

Have you got the scope balanced properly.

If I am reading this right you had to take the RA back to get to the moon.

It sounds like you have a bit of 'creep' (for want of a better word )going on there Mike.

Are the clutches holding ok?

[Perkil8r]

It was only say about half a lunar dia out of position, balanced well and clutches tight. Hopefully just a difference in the speeds then.... That's a relief.

[Tweedledee]

Yes.

Very roughly, the moon will lag behind your tracking by about a quarter of a degree in half an hour.

Half a lunar diameter is about a quarter of a degree.

Sounds like normal tracking and nothing to worry about.

[Perkil8r]

Excellent, thank you for that, I now feel a lot more confident.

[Brantuk]

On the "goto" mounts there's usually a lunar rate, solar rate, and sidereal rate to choose from because they all do vary slightly from one another. The "tracking only" mounts usually just have sidereal rate plus a couple of higher speed slew rates. If you didn't have to adjust Dec then it sounds like PA is accurate, and the difference between sidereal and lunar rate is whats happening here. Nothing to worry about Mike

[Perkil8r]

It is the answer I was hoping for, but being a born unlucky I was looking on the dark side lol Thanks for all the replies, it's put my mind at rest.