'Rack Focus' problem ML2.3, Canon 600D, 50mm 1.8.

Started by pipkato, October 06, 2012, 05:13:58 PM

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Can someone please help me with the 'Rack Focus' option on a Canon 600D, 50mm 1.8 in manual focus mode, with ML 2.3?

I've watched YouTube tutorials and read the user guide but can't get it to work.

For some reason I can no longer get my 'Magic Zoom' window to display either, although I've set it to work on Focus and Zoom.  I do sometimes see the 'Magic Zoom' window but I don't know why it's sometimes there and at other times is missing.  I did at some earlier stage get a full screen version of Magic Zoom (which I like) but could never get it back again.  when I focussed it gave me a full screen image of the zoomed in area, and it was great for focus.  I can force the small Magic Zooom window to appear by selecting 'Always', but I'd prefer to have it appear only when I attempt to focus.

I'm following the Wiki User Guide instructions for ML 2.3 and picking the End Point of the focus change.

Then I go to Focus End Point and press Set which sets it at 0.

Next I try to focus on the Start Point using the + and - magnification buttons.  But instead of focusing it just enlarges or  shrinks the image as it normally does.  So I can't focus on e.g the foreground.

Can anyone see what I'm doing wrong?



Not all lenses work with the Focus and Zoom MZ trigger, only ones that report focus info I'm guessing. This includes the 50mm 1.8, which is not particularly the most advanced lens.

To change the focus for Rack Focus, don't use the Zoom In/Out buttons, use the directional buttons.


Thanks very much Francis.

I'm afraid I have to make one red-faced confession - it never occurred to me that I had to have my lens set to 'AF' for this to work at all.  I'm not really an 'AF' person and tend to focus manually.

In addition, as you comment about the correct buttons underline, I was working from a combination of YouTube tutorials and the Magic Lantern User Guide from this site, and obviously the buttons used have changed as the firmware moved towards completion.  So the YouTube tutorial I was using told me to use the + and - buttons, but I should have been using the 'Left' and 'Right' arrow keys.

Even so I found grasping exactly how to do 'Rack Focus' difficult, and sometimes in the middle of setting it up I'd press the wrong button and be back where I started.  I did manage it once today, so I know it works, but have not had the time to keep trying.  I found that fine-tuning the focus was very difficult, and was not so much a 'fine-tune' as a 'rough-tune'.  So I think I need to read it all again very slowly and try to understand what role, if any, the various step sizes play in this fine-tuning.

ML2.3 is an amazingly sophisticated and powerful utility and a great addition to my Canon cameras, but I sometimes find it a little overpowering in practice. 

I think I should take a weekend and read that User Manual carefully from end to end.  Can't help feeling that there's a really good gap in the market for a proper ML2.3 tutorial series online or with Lynda.com or some other such provider.

Thanks again.

Angry Video Guy

I can't seem to figure out the rack focus myself...too many youtube tutorials with different cameras and different versions of ML. I am using a T2i and a 7D and am getting focus error :( message when i am trying to focus on my start point. I know how to set the end FOCUS point to ZERO but when I try to set the start point i sometimes get thefocus error :( message. I am using a cheap 50mm 1:8 canon lens and a pretty sweet Sigma 30mm 1:4

I seemed to had a hang of the rack focusing before i installed the nightly build onto my T2i...now it seems wonkier.

I would also love to know how to fine tune focus for my rack start and end points (zoom in and focus both points before recording) there are many videos on youtube on this but the verions of ML have changed and i cant find any info on what buttons do what.

Angry Video Guy

Here is a copy and paste of the instructions...i changed the step size to 1 and the step delay to 40 ms and the rack focus is working with no errors! anyways...what these instructions are missing is how to fine tune your end and start points for rack focusing...I have not seen one video on how this is done properly and now that i have it figured out on my own* its sweet!!!

Triggers the rack focus operation that moves between the start and end focus points. After the move is complete pressing again reverses the move.

    SET: rack focus will start after 2 seconds;
    Q: rack focus will start immediately;
    PLAY: ML will automatically record a short clip with the rack focus operation.


    Pick the end point of rack focus by focusing on it (manually or with AF).
    Configure focus parameters (step size and delay). Different lenses may require different parameters.
    Open the Focus menu, go to Focus End Point and press Set to zero it out.
    Pick the start point by focusing on it with the LEFT/RIGHT buttons while the Focus menu is active. Make sure the number from Focus End Point is changing as you focus. Fine-tune the position with scrollwheel.
    Go to Rack Focus and press SET or PLAY to start rack focus.
    To return to the starting point, run rack focus again.


    while recording, you can start rack focus from outside the menu, by pressing PLAY.
    when LCDsensor Remote is set on Near or Away, you can trigger rack focus from the LCD sensor, avoiding camera shake.

Recommended focus step settings:

    Focus StepSize: 1 or 2
    Focus StepDelay:
        without Step Wait: large delays (around 100 ms) ⇒ will ignore small position errors
        with Step Wait: small delays (use it only if your lens is in very good mechanical condition)

* fine tuning your focus is pretty tough to explain...