Hocus Focus for newbie - Forums

Topic starter

Feb 23, 2023

I am trying to learn the NINA "Hocus Focus" to help me with back focus.

I am NOT currently trying to use HF with a tilt correction device. I merely wish for the moment to know how/when to use HF to give me its opinion about too close to the sensor or too far from the sensor.

In settings, I thought I configured all the AF stuff to be done by HF, I selected the HF choices. But then what? Instructions for using HF seem to be non existent.

Do I run HF during a regular imaging session, or is a dedicated test session on a big star field required? When I push the aberration inspector button, I don't see anything about the back focus.

Engaging

Jonny Bravo

Feb 23, 2023

I haven't run Aberration Inspector for a while... mostly because I found myself spending WAY too much time chasing things down instead of imaging. Here's a screenshot of a run I did:

This gives a few bits of crucial information. First, looking at the focus curves, I can see that things are off. Ideally, all of those curves are on top of each other, indicating good spacing and minimal field curvature. The second bit of information is the back focus error. It's telling me I'm too close and need to adjust my spacing to move the sensor away from the reducer/flattener.

There's also a 3D model of tilt and field curvature. Looks like this:

As you can see, I had both tilt and field curvature issues to resolve.

Well Written Helpful Insightful Engaging

Paul Wilson

Topic starter

Feb 23, 2023

And you get this screen when you run an AF from the HF plugin?

Paul Wilson

Topic starter

Feb 23, 2023

And so you worked on tilt/field curvature, I am assuming, with a tilt correction device like an Octopi or a photon cage?

Jonny Bravo

Feb 23, 2023

Paul Wilson:
And you get this screen when you run an AF from the HF plugin?

The screen is a separate one called Aberration Inspector:

You execute it by hitting the "Run Auto Focus" button up top. Mine's disabled because nothing's connected currently (rig is in the garage).

Paul Wilson:
And so you worked on tilt/field curvature, I am assuming, with a tilt correction device like an Octopi or a photon cage?

No, I went decidedly low-tech. I bought some spacers from Agena that I slip in between the threaded components. Are they perfect? Nope... but quite a bit cheaper than the Octopi or other such devices

Paul Wilson

Topic starter

Feb 23, 2023

Jonny Bravo:
Paul Wilson:
And you get this screen when you run an AF from the HF plugin?

The screen is a separate one called Aberration Inspector:

You execute it by hitting the "Run Auto Focus" button up top. Mine's disabled because nothing's connected currently (rig is in the garage).
Paul Wilson:
And so you worked on tilt/field curvature, I am assuming, with a tilt correction device like an Octopi or a photon cage?

No, I went decidedly low-tech. I bought some spacers from Agena that I slip in between the threaded components. Are they perfect? Nope... but quite a bit cheaper than the Octopi or other such devices

*** Ah! Ok, that's how you run it. I had not gleaned that, so thanks! ***

Bill Poplawski

Sep 15, 2023

Paul, thank you for asking the question. Jonny, once again thank you for providing quality information! I'm going to run Aberration Inspector tonight clouds permitting to check mostly backfocus which is my immediate interest. I'm interested in tilt as a second priority at his point.