Autofocus Rigel nStep


#1

I must be misunderstanding something. I have been trying to get autofocus to work for DAYS and it never works right. Here is what I’m doing:

I use a bhatinov mask to get perfect focus. Then I take note of the current position (lets say for example for my HA filter) and note it’s at 8920. I then go in and set the focus pt for the Ha filter at 8920. I do this for all of my other filters taking note of the current position and once I get focus I put that into the focus pt.

As soon as I try to switch to another filter after all of my focus pts are set, it will go to the correct position but the frame is out of focus. I’m totally confused and completely new to autofocus. Please help :joy:

Edit: Just to add to this. I just tried to set my autofocus point for my Ha tonight. Last night the position of 8920 was the focal pt. Tonight, however the position that I’m getting focus is 11095. Obviously it’s not going to get focus if it uses 8920 and for some reason tonight it focuses at 11095.


#2

Hi,

what’s the actual distance / step in your setup? 2000 steps sounds like a lot, seems too much even if the diff in temperature between both nights was huge.

Either you’re losing steps, and then track of the real position, or the position is lost after a session… I’d say ?


#3

Thanks @jaime - I looked into this deeper last night and indeed, you are correct. My telescope has a crayford focuser on it and it was slipping from the weight of the equipment when I was trying to focus in. I tightened up the screws on the plate of the focuser, so hopefully my next test will see some improvement.


#4

Yep, many crayford focusers are not up to the task, with today’s gear… rack and pinion ones are back!

Good luck


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