Hi all,
I picked up an Esprit 120 recently and unfortunately it's been a bit of a frustrating time with it so far. I am really, really struggling to get the nice round stars I'm accustomed to on the Esprit 80.
Imaging on a 533MC Pro, my pixel scale is about 0.92" per pixel on the 120 so definitely a lot more challenging than on the Esprit 80 and that's fine. But I'm kind of at a loss as to what I need to do to improve matters, short of spending obscene money on a better mount. My mount is an EQ6-R Pro currently.
First light with the 120 was earlier this month and unfortunately most subs showed star elongation. I put this down to guiding quality as my guiding wasn't amazing that night and I was just using a small findershoe guide scope (which has served me fine on the Esprit 80, perhaps not on the 120.) I replaced this with a much better, more rigidly mounted guide scope but unfortunately my next session still showed elongation issues
One other variable aside from the guide rig that changed between sessions is that for the first session I used the regular Skywatcher field flattener that ships with the scope. The 2nd session I used the newish Skywatcher 0.77 reducer/flattener designed for the Esprit 120 (sold seperately.) Now I could be wrong (I'd appreciate any expert opinions here) but to my eye the elongation "pattern" is actually different from session 1 to session 2 - ie potentially, maybe, two different problems I am dealing with.
I'm assuming guiding is the driving factor behind the elongation with the standard field flattener, in part because the elongation seems to all point in the same direction across the entire frame, and in part because I did manage to capture a few (not many, but a few) subs that look just fine with this flattener. With the reducer/flattener though, the stars seem to point in different directions depending on where in the frame you look.
Here is a link to some .fit files showing the problem, as well as some guide logs. I've included some sample .fit files using both the standard flattener and the reducer/flattener, and have included a few that, to my eye, look OK as well.
I'd very much appreciate any opinions people have after looking at the files about whether I am dealing with two different issues here, and what the likely causes are? I've posted a similar thread elsewhere but also keen to hear from users here about what they reckon the issues could be? Right now the theory is guiding for the standard flattener, and perhaps backspace for the reducer/flattener. Overall, it has not been a fun step up to the 120 unfortunately, with very little usable data gathered and much frustration trying to figure this out.
Cheers