Celestron XLT 150 / Skywatcher 150p - Mount weight limits and drive accuracy?

[metronome]

The unguided tracking accuracy will be no better than the EQ3 Pro. I only get 2 minutes unguided with my NEQ6! The EQ5 will give you better stability against the wind though, which will be a big help and can be used with autoguiding in the future (after your first couple of images, you will want to guide )

What about PEC? I understand that it would work only if the scope are well aligned, but what difference does it make? I'm about to get a NEQ6 myself (will use autoguiding though), and I was pretty sure that NEQ6 provided at least a bit more accuracy than CG4/EQ3-2.

[RikM]

I don't use PEC on the NEQ6. It guides out fine. I have done a few 30 min subs and the stars were round enough for me. Unguided though, at 750mm focal length, I have got longer subs with my EQ3-2 (but I think I got a good one ) Normally 90 sec but I have had a few sessions of 3 min subs out of it. With my NEQ6 I have never got longer than 90sec. To be honest I haven't put that much effort into getting the 6 running unguided. That's what I bought a finder guider for

I have heard a few people say that the EQ3 is smoother than the EQ5, and that the HEQ5 is smoother than the NEQ6. That matches my experience but smoothness isn't everything, stability / steadyness is a major factor. Go for the biggest mount you can afford and put the smallest fastest scope you dare on it

[metronome]

Useful information indeed! As I mentioned in my previous posts, I managed to get 3 mins subs from my metal grinding CG4 once also, but I bet it would never happen again

I'm pretty sure you could get a few secs more if fiddling with PEC, EQMOD and other toys, but as you say - guiding makes all that unnecessary.

Regardless, NEQ it is - anything bigger would make it too impractical to move and my wallet very thin....

[NeilFawcett]

I have heard a few people say that the EQ3 is smoother than the EQ5

Don't confuse me!

[metronome]

Don't confuse me!

Don't worry. As Rik says, smoothness isn't everything. It's all a combination of smoothness/accuracy, balance and steadyness of the mount. And of course, the capability of pushing all the calculated weight around. It's simply not possible to get very long exposure times without guiding, regardless of which mount you actually use. Go for a EQ5 Pro, if you can afford a NEQ6 it's even better, but trust me, it will do the job!