Focusmax - Vcurve Routine

[leinad (Dan)]

my Equipment specs:
Starlight Feathertouch with Wireless Autofocusing System
QHY8 OSC
Vixen VC200L F/9
Latest verison of Focusmax
Windows 7

Ive been pulling my hair out on numerous nights trying to get Focusmax working correctly. It keeps failing or crashing and I have a feeling it may have something to do with the QHY and binning or another obvious error. MaxDL allows me to bin 1x1, 2x2, 4x4 (3x3 is a no go)

It appears to be taking an initial exposure; then binning a 3x3 or 2x2 sub-frame and then it's looking for the star and various subframe sizes to start it's focusing/vcurve routine, however it fails and cant find the star; out of frame or too faint.

I'm lost of what it's trying to do. I placed a magnitude 3-4 star in the center of the frame, focused as close manually as I could and started the routine, yet it fails to work every time.

I eventually gave up and used MaxDL's Autofocus instead.

I think I only got it working once and that was with the star placed in the very top-left hand corner of the exposure frame.

I should have taken notes of what I was doing at the time.


If anyone can assist it would be greatly appreciated.
Thanks

[Jeffkop (Jeff)]

Hi Lienad

Your testing my memory here, and thats always fraught with peril, however I seem to recall having the same problem. In the end I think I worked out that putting a box around the star you want to use cured it.

I hope this helps

[Bassnut (Fred)]

The small box it brings up is not binning, its just makeing the view box smaller. Too small, and it will lose the star if it drifts out of view. Try increasing the box size.

Are you setting the max exposure time in focus max?, it will attempt exposures up to the time you set, no longer.

If you have other dimmer stars or hot pixels in view, it may select them. Also, dont have nebs/galaxies etc in the view, pick a view that has a bright star in the middle.

[jase (Jason)]

During the focus routine or that of establishing a v-curve, it shouldn't be binning the data at all. 1x1 all the time. It can however 2x2 or 3x3 for platesolves associated with the AcquireStar process. Leave this disabled until you get your v-curve established. Fred's suggestion is a good one - increase the frame size will improve chances if the star wanders.

[Hagar (Doug)]

Hi Leinad, The first time I used Focusmax I suffered the same indignity that you seem to be suffering. I was using Robofocus on an FSQ106ED which has a relatively short focus travel and had step size set to 4. I could not get a v curve to complete properly. I read in the notes something about step size and changed the step size to 1 and after a lot of error messages which I chose to ignore the whole thing worked and worked very well. I would not be without focusmax and robofocus, at least by choise. Focus Max doesn't work under Windows7 which is a pain in the backside so I an back to standard Robofocus and Bahtinof mask. I have asked the originators of Focusmax if there is a work around but haven't heard from them.

[leinad (Dan)]

Thanks guys for the feedback.

Hagar what do you mean Focusmax doesn't work with W7?
You have latest patch from D3C-Dreams website?
Is there a procedure that doesn't work ? Ive got it working fine here, had it working once perfectly, but had no idea what I was doing and now cant get it working at all.

Jeff/Fred,

Do you mean I need to expose then select the subframe box to highlight the star to begin the vcurve routine on?


Ok so by default we have Frame Width:100, Bin:2, Exp:0.5

First I set my end points 1000 low and 1000 high of best focus, and step size to 1.

If my QHY8 has a frame width of ~2000 and I have a centered star, I should use a large frame width of close to 2000?

I read that Exp time should be around 0.11 to 0.5; however I'm running at F/9 1800 focal; so I could actually set at 10sec and focusmax will run exposure times low to high; maximum being 10secs to find the star.

I assume all this will do is increase the time to auto focus?

When I watch Maxim running in the background during the vcurve routine, I thought I recalled it binning at 2x2 or 3x3 using a very small subframe box of the image. I'll have to pay more attention to this in future.

[Bassnut (Fred)]

Increase the exposure time to something like 2 secs, this works well for me with mag 5 stars. The min time is attempted for focus, a 2 sec max does not increase focus time. The frame width 100 should be OK, try 200. Those end points look huge, it depends on the focuser count range. If its too big, focus will be so far out to start it will lose it, try something much small. Manually defocus to see the count range whilst still having a bight image.

[leinad (Dan)]

Hi Fred,

My focuser starts at 30000, ends at 42000. So do you mean to have a start point and end point that is just enough to defocus the star; say only 100 or less steps if my focus point is at 36050 roughly?

[Bassnut (Fred)]

Well, my focuser is in focus about 19800 and the start point is 20020, so , make the end points say 35600 to 36400.