Setting up the ZWO EAF

damianvines

When installing an EAF, in this case a ZWO EAF on an Edge HD8.. When you physically connect (lock down the set screws) in what position should the focus knob or wheels be in? Meaning, should the knob be half way from close focus to infinity?.. or roughly in the correct focus spot when you lock down the EAF? And... when you set the "0" position in whatever software you use, and set the total number of steps to say 60,000.. Does that mean the motor will turn -30,000 to +30,000 steps? My concern is having the motor accidentally try and turn the focus knob past it's end point and cause damage 🙁

sebriviere

1st, you need to understand your mirror position in relation to focusing.
Is it near focus (like daylight style, watching distant landscape) or near infinity focus, astro/star focus.
Then, which way does the know has to rotate (clkwise or ctr-clockwise) -> will determine if EAF will work in normal or reverse.
Then how many turns (complete revolutions) between some close objects (moon) or distant DSO -> will give you number of turns for the 60000 steps of EAF.

Easiest is then to position your EAF and allow couple of turns one way, keeping remaining range for other direction.

EAF cannot work in negative values.
So if you set it like above, depending on rotation direction you choose (normal / reverse), once in place you set it electronically to the position ( 15000 or 45000)...

You just then have to check your focusing range covers your needs....

normal/reverse may also have an impact on mirror shifting, as AF sequence is always going in same direction.

raw focus -> jump 150 steps -> move back down 30 steps increments building V curve.
Once estimated focus position known, EAF jump another 45 steps up above estimated focus position, then back down by 15 steps increment until confirmed focus position is obtained.

So chose as to ensure your mirror is shifted the right way reaching focus.

damianvines

Thank you very much sebriviere