I'm struggling to get consistent auto focus with my Moonlite NiteCrawler. One setting that has me confused is on the filters panel from the Focuser tab. There's a column in this grid "Flat Focus Position". Where do these values comes from? They have wildly differing values for my LRGB filters. Lowest value is 49 and highest is 48,000 (and a couple in the 38,000 range) . I typically find good focus in the 49,000 to 50,000 range. These values are not editable, so I assume that they are being derived from somewhere.
Focusing has failed for me every night I've tried to use it - in the morning I find everything aborted and the last images WAY out of focus (10,000 steps or more). Is there a good youtube video that covers setup?
I use Nightcrawler as in my home observatory, it's my primary driver for focusing/rotating. The key is to limit the maximum travel to something less than 5000 steps so the algorithm remains restricted to that zone. You need first to the OK focus position (e.g. 49,500) and then start the auto focus from there. You can even restrict max travel to 3000 or less. Select step as 500, and limit as 3000 and go from there. Depending on your optical setup, you can try different algorithms. Are the starts getting properly detected? Are you using subframing?
Once you reach a very good focus position, change the step size to 100 and limit to 1000 or 2000.
Thanks for the info. That makes a lot of sense. My next question was going to be, how to I stop the focuser from going so far off focus that it can't get back - but you've answered that for me! I've gone back ad forth on subframing - I had issues with "no stars detected" when I moved to my second target, so I decided to stop using that until I sort out the other issues. When it worked, it seemed like I was getting a better V shape. Btw, I love the Moonlite NiteCrawler; beautifully engineered piece of kit.
Not making any progress, in fact I went backwards! I had to abort my schedule when I noticed that the subs were being taken with a gain of 170, rather than 113. It seems like the gain in the camera tab is getting set to the gain value in the focuser tab (eve though it was initially set at 113). The only way I could work around this was to set both to 113. My first target focused ok (at which point I had to go to bed). But all subsequent targets failed. This morning I found the focus at 0! Perhaps at 113 the images were too thin? I guess I'll have to try increasing the exposure times for focus, or just give up on multiple targets in a single evening. I've lost too many nights imaging not to consider that.
The only time this has run to completion was when I first discovered that I was getting the wrong gain setting for the subs (all my subs were at a gain of 170). On that occasion, I assumed that I had incorrectly set the value in the camera tab,. Is it the intent that the focuser gain has to be the same as the focuser? That would seem odd; or am I doing something else wrong that's causing this? It doesn't like the sequence files contain a setting for gain. As far as I'm aware, the only places I am setting the gain are: the default value in the camera's indi Control Panel, (113) the value in the focuser tab (170, then dropped to 113) and the value in the camera tab (113 when I started, but ended up at 170 before I aborted).
Something went wrong to send the focuser to an absolute position of 494. That value does not reflect the previous inward focus move. The previous focus position was 49740. It looks like the 245 inward move was subtracted from that, giving 49,495 and then the number was truncated to 494.