Focus Stacking Helper Script

[garry23]

I hope this post and script helps others who are learning/struggling to become 'scripters'.

I couldn't have got this far without the help of David Milligan and others, who have provide feedback.

Although learning Lua scripting is easier than trying to code in ML C, Lua still requires some effort to learn, especially while the 'user manual' is being developed. For instance http://davidmilligan.github.io/ml-lua/index.html helps, but there are still areas where the user is left 'guessing'.

As a scripting newbie, I have spent tens of hours experimenting and trying to divine coding errors. I have educated myself on event driven programming and now have a reasonable looking script to offer the ML community.

This script's only purpose is to provide in-camera feedback to aid landscape (sic) focus stacking, ie NOT macro focus stacking.

The caveats are the lens must report focus distance and DoF, and LV must be on.

Before using it is best to check if the ML DoF is set up correctly, eg I recommend switching on the diffraction aware option.

I have positioned the script in the Audio menu (my preference), but this can me moved elsewhere.

Here is the script, which you should put in a text file with a .lua extension and place this file in the ML script folder.

Code Select Expand

--[[
Manual Landscape bracketing helper script
Version 0.3.3
Garry George Feb 2016
http://photography.grayheron.net/
First focus at nearest bracket in focus stack then move towards infinity.
Try using ML follow focus to control lens, as opposed to rotating lens by hand.
Yellow means move more towards the infinity end, Red means move more towards macro end,
Green means at the sweet spot. If Green not seen, move to just being in the Yellow from being in the Red.
************************
* Must be in liveview! *
************************
--]]
a1 = lens.dof_near
b1 = lens.dof_far
c1 = 0
fp = lens.focal_distance
inf = 1000000
started = false

event.keypress = function(key)
if keymenu.submenu["Turn On/Off"].value == "Off" then started = false end
if fp ~= 0 then
if key == KEY.UNPRESS_FULLSHUTTER
then
b1 = lens.dof_far -- in mm
fp = lens.focal_distance -- in cm
if keymenu.submenu["Bracket to bracket overlap"].value == "20%" then
factor = .2
elseif keymenu.submenu["Bracket to bracket overlap"].value == "10%" then
factor = .1
else
factor = .05
end
c1 = b1 - (b1 - fp*10)*factor
started = true
end
end
end

lv.info
{
    name = "Landscape Stacker Info",
    value = "",
    priority = 100,
    update = function(this)
    this.value = ""
if fp == 0 then
this.value = ""
else
    if keymenu.submenu["Turn On/Off"].value == "On"
    then
    if started then
a2 = lens.dof_near
this.value = ""
if a2 > b1 then
this.background = COLOR.RED
elseif a2 < c1 then
this.background = COLOR.YELLOW
this.foreground = COLOR.BLACK
else
this.background = COLOR.GREEN1
end
if lens.dof_far >= inf then
this.value = "Inf"
else
this.value = "   "
end
end
else
this.value = ""
end
end
end
}

keymenu = menu.new
{
parent = "Audio",
name = "Landscape Stacking Helper",
help = "First focus at nearest point in bracket set",
help2 = "and take first picture",
depends_on = DEPENDS_ON.LIVEVIEW,
submenu =
{
{
name = "Turn On/Off",
help = "Switches the script on/off",
depends_on = DEPENDS_ON.LIVEVIEW,
choices = {"Off","On"},
},
{
name = "Bracket to bracket overlap",
help = "Amount to overlap each bracket",
help2 = "% of FP-2-DoF(far) distance",
choices = {"20%","10%", "5%"},
}
}
}

The script, by default, is not running. To switch it on, go to the menu and switch to 'on'.

Also change the bracket to bracket overlap. The default is 20%, but you can reduce this to 10% or 5%. The % represent the % of the distance between the current bracket's DoF(far) and the focal_distance. According to the lens you may not see the effect of this variable.

Do a half shutter press to get rid of the script's menu and, of course, ensure you are displaying the ML top and bottom bars of information.

To use the script, once switched on, position the lens at the first (closest) bracket and take a picture. You will then see a helper flag (coloured block) come on.

The coloured blocks have the following meaning:
* Yellow = move the lens towards the infinity end
* Red = move the lens towards the macro end
* Green, if seen, means the lens is in the 'sweet spot', according to the % overlap criterion

If you don't see green, but just yellow or red, simply move the lens into the yellow position just before it goes red.

Each time you take a picture move the lens closer to the infinity end until you see INF in the coloured block. This means the DoF-far has reached infinity: you may wish to take an insurance shot beyond this.

Consider using the ML follow focus to move the lens, as this is more controllable than trying to manually position the lens.

To take a new set of brackets, simply reposition the lens to a new closest image and take a picture to reset the bracketing sequence. Consider grabbing a bookend image to separate your bracket sequences, eg an image of your hand: this will help in post processing, especially if you are not recomposing.

Bottom line: I have tested the script on my 5D3 and 24-105 F/4L and it works for me. I hope it does for you. As usual I welcome feedback on this script. Also note that my next project is an automated version of this, but I can't finish this until the next Lua update is pushed out, eg fixing the lens control by Lua.