AlexN
09-07-2024, 02:01 PM
So You'd think throwing an EAF on a scope would just resolve all your focus issues, right... You'd just tell your imaging software to refocus every couple of hours, or on > 2°C temp shift, or on 10% HFR increase and all your subs should then be in focus... That's the plan...
So, throwing the 3rd axis balance issues that plagued me for ages (2.4kg telescope with 400g of off-axis weight attached to the rear left of the scope) aside, here's the situation....
I run an AF routine with focus absolutely spot on (bahtinov mask confirmed), the v-curve looks reasonable, perhaps 10 steps off on the backlash give or take, with a slightly flattened edge to the right hand side of the v curve. I usually get 2 points that are roughly around the critical focus zone... Once it gets to its final position, the HFR will be worse than original focus, sometimes as far as 100 focuser steps off.
I test this via first looking at the starting and finishing HFR's being significantly different, then throwing the bahtinov mask on the scope, checking the focus and manually adjusting 8~15 'fine focus movements' on the focuser controller in NINA until the bahtinov mask then confirms accurate focus.
This has been going on since I got the EAF, and it's particularly annoying.
I don't mind manually focusing, if I haven't spent $400 on a system to do it for me.. but having spent that money, having to manually fix focus when I check it after an AF run and the stars look bloated is not what I had in mind when buying an AF system for my scope.
This is the last thing I'm manually having to adjust during a night of imaging, and I'd really love to be able to fire off a target sequence, and then leave it to do its thing...
Anyone got suggestions?
For reference,
The gear is:
Askar 65PHQ (with and without the 0.75x Reducer)
ZWO EAF (5v)
Focuser load is:
Player One Artemis C Pro,
Player One Filter Drawer,
Player One OAG
Maybe 1.5kg total including the reducer.
In NINA, my settings are currently
Backlash set to 60 on the out direction, backlash compensation mode is set to overshoot, step size is 50, initial step count is 3.
So, throwing the 3rd axis balance issues that plagued me for ages (2.4kg telescope with 400g of off-axis weight attached to the rear left of the scope) aside, here's the situation....
I run an AF routine with focus absolutely spot on (bahtinov mask confirmed), the v-curve looks reasonable, perhaps 10 steps off on the backlash give or take, with a slightly flattened edge to the right hand side of the v curve. I usually get 2 points that are roughly around the critical focus zone... Once it gets to its final position, the HFR will be worse than original focus, sometimes as far as 100 focuser steps off.
I test this via first looking at the starting and finishing HFR's being significantly different, then throwing the bahtinov mask on the scope, checking the focus and manually adjusting 8~15 'fine focus movements' on the focuser controller in NINA until the bahtinov mask then confirms accurate focus.
This has been going on since I got the EAF, and it's particularly annoying.
I don't mind manually focusing, if I haven't spent $400 on a system to do it for me.. but having spent that money, having to manually fix focus when I check it after an AF run and the stars look bloated is not what I had in mind when buying an AF system for my scope.
This is the last thing I'm manually having to adjust during a night of imaging, and I'd really love to be able to fire off a target sequence, and then leave it to do its thing...
Anyone got suggestions?
For reference,
The gear is:
Askar 65PHQ (with and without the 0.75x Reducer)
ZWO EAF (5v)
Focuser load is:
Player One Artemis C Pro,
Player One Filter Drawer,
Player One OAG
Maybe 1.5kg total including the reducer.
In NINA, my settings are currently
Backlash set to 60 on the out direction, backlash compensation mode is set to overshoot, step size is 50, initial step count is 3.