MaxIM 3D plots

[LewisM]

I am not sure what I am expecting to see in MaxIM regarding the 3D plot of star focus - is ANY degree of flat top "acceptable" or is the aim to get a pointed top showing a perfectly focused star image?

I am still hand-focusing, and am getting some pretty tight 3D plots, but do I need to aim for the pointed spire? (probably nigh on impossible hand focusing in the CFZ with an f/5 scope).

My Sharpsky will be up and running later this week.

[Atmos]

You think that's bad, I am trying to focus a F/3.76 guide scope :P

[Peter.M]

Flat tops do not indicate lack of focus. Generally it is the star saturating at the center.

[LewisM]

Thanks Peter. I wouldn't have thought that they would saturate that much in a 10 sec exposure on medium magnitude stars, even at f/5.

[LewisM]

One word -helical focuser. You can get one for around $70 and retrofit it to an 50mm tube finder etc. (old image, but same guidescope conversion)

Image below. makes life a breeze!

[Atmos]

Already got one :) Only properly figured out how to use it yesterday afternoon so I haven't actually had a decent focus out in the field yet :/