CHDK Get Focus Script Rev 2

gfbs2.lua

--[[
@title Get Brackets
Capture 'Perfect' focus brackets, with focus overlap defined in terms of defocus (CHDK Circle of Confusion (CoC)) blur
Plus option of additional exposure brackets at each focus step, using various logic: 1Ev, 2Ev or 3Ev using -/+ or -/-- or +/++; one iso-invariant at
ISO at 800 or 1600; or one (Zero Noise) exposure at 4Ev, 3Ev or 2Ev
Focus bracketing strategies are: current position to blur-defined infinity (X2Inf); min camera focus to current position (Min2X), min camera focus to blur-defined infinity (Min2Inf); 
current position to a delta x ahead of the current position (X2DelX); from a delta x in front of the current position to the current position (-DelX2X); 
from a delta x in front of the current position to a delta x ahead of the current position (-D2+D).
None means that requested exposures will only be captured at the current focus point
Overlap, ie bracket to bracket focus insurance, is definded in terms of the defocus (CoC) blur, eg CoC/2 means focus brackets 'touch' at a blur of CoC/2. 
Where as diff means that the defocus blur and the diffraction blur, taken in quadrature, equals the CHDK CoC value
Unless, under focus strategy, none is selected or the delX option is selected the script will take three focus brackets, even if initial focus is beyond the defocus hyperfocal (H), 
ie at H/3, at H and at the blur-based infinity, which means DoF will go from H/4 to infinity. Thus focusing is not critical, just ensure focus is beyond H (+ have CHDK show focus & H)
Use Bookends to help differentiate bracket set in post
Option to switch LCD screen off during shooting
Rev 1.7
Jan 2020
Tested on a G7X and G1X
Garry George
@chdk_version 1.5
# focus_strat = 0 "Focus logic?" {X2Inf Min2X Min2Inf X2DelX -DelX2X None -D2+D}
# overlap = 0 "Overlap at" {CoC 2CoC/3 CoC/2 diff}
# quality = 2 "Infinity quality?" {CoC/2 CoC/3 CoC/4}
# delx = 10 "Focus delta (mm)" [5 100]
# delta = 0 "Exposure delta?" {None 1Ev 2Ev 3Ev 800 1600 ZN4 ZN3 ZN2}
# logic = 0 "Exposure logic?" {0/-/+ 0/-/-- 0/+/++}
# delay = 3 "Script Delay (s)" [0 5]
# bookends = 1 "Bookends?" {No Yes}
# screen_off = 1 "Screen off?" {No Yes}
# num_braks = 10 "Max num of brackets" [5 20]
--]]

capmode = require("capmode")

function restore()
    if x_start == -1 then refocus(1000000) else refocus(x_start) end
    set_tv96_direct(s)
    set_av96_direct(av)
    press("shoot_half")
    repeat sleep(10) until get_shooting()
    sleep(500)
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())

    if current_focus_mode ~= 1 then set_mf(0) end
    if (current_mode ~= "M") then capmode.set(current_mode) end
    set_lcd_display(1)
    exit_alt()
end

function set_up()
    current_focus_mode = get_focus_mode() 
    current_mode = capmode.get_name()

    if current_focus_mode ~= 1 then set_mf(1) end

    dof = get_dofinfo()
    x = dof.focus
    x_start = x
    last_x = x
    base_h = dof.hyp_dist -- that is without diffraction accounted for
    fl = dof.focal_length/100

    s = get_tv96()
    av = get_av96()

    if (current_mode ~= "M") then capmode.set("M") end

    set_tv96_direct(s)
    set_av96_direct(av)

    press("shoot_half")
    repeat sleep(10) until get_shooting()
    sleep(500)
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())

    return true
end

function myshoot() -- works inside X_bracket function
    shoot()
end

function bookend()
    set_tv96_direct(960)
    set_av96_direct(640)
    local ecnt = get_exp_count()
    myshoot()
    set_tv96_direct(s)
    set_av96_direct(av)
    press("shoot_half")
    repeat sleep(10) until get_shooting()
    sleep(500)
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
end

function refocus(xx)
    set_focus(xx)
    dof = get_dofinfo() -- update info
end

function X_bracket()
    set_tv96_direct(s)
    if delta == 0 then 
        myshoot()
    elseif delta < 4 and logic == 0 then
        myshoot()
        set_tv96_direct(s-96*delta)
        myshoot()
        set_tv96_direct(s+96*delta)
        myshoot()
    elseif delta < 4 and logic == 1 then
        myshoot()
        set_tv96_direct(s+96*delta)
        myshoot()
        set_tv96_direct(s+2*96*delta)
        myshoot()
    elseif delta < 4 and logic == 2 then
        myshoot()
        set_tv96_direct(s-96*delta)
        myshoot()
        set_tv96_direct(s-2*96*delta)
        myshoot()
    elseif delta == 4 then
        local iso = get_sv96()
        myshoot()
        set_sv96(sv96_market_to_real(iso_to_sv96(800)))
        myshoot()
        set_sv96(iso)
    elseif delta == 5 then
        local iso = get_sv96()
        myshoot()
        set_sv96(sv96_market_to_real(iso_to_sv96(1600)))
        myshoot()
        set_sv96(iso)
    elseif delta == 6 then
        myshoot()
        set_tv96_direct(s-96*4)
        myshoot()
    elseif delta == 7 then
        myshoot()
        set_tv96_direct(s-96*3)
        myshoot()
    elseif delta == 8 then
        myshoot()
        set_tv96_direct(s-96*2)
        myshoot()
    end
    set_tv96_direct(s)

end

-- Main section

if not set_up() then -- at the moment set_up() always returns true ;-)
    restore()
    return -- exit script
end

if screen_off == 1 then set_lcd_display(0) end

h = base_h -- no overlap case: brackets 'touch' at CHDK CoC

if overlap == 1 then -- adjust h to achieve the requested overlap, ie 'touching' at 2*CoC/3 or CoC/2 or at the diffraction aware defocus blur
    h = (h*3)/2
elseif overlap == 2 then
    h = 2*h
elseif overlap == 3 then -- use diffraction aware overlap: Assume CHDK CoC is total blur, formed in quadrature from defocus and diffraction blurs
    temp1 = 1000*dof.coc -- total blur set up for imath
    temp2 = (1342*dof.aperture)/1000 -- set up for imath. From diff_blur = 2.44*0.55*N (um)
    if temp1 > temp2 then -- can use diffraction aware overlap
        temp = imath.sqrt(imath.mul(temp1,temp1) - imath.mul(temp2,temp2)) -- diffraction aware defocus blur
        temp2 = imath.div(temp1,temp)
        if temp2 > 3000 then 
            h = 3*h
        else
            h = (h*temp2)/1000
        end
    else -- diff blur > total blur
        h = 3*h
    end
end

if (1 + (h/x))/2 > num_braks then -- too many brackets needed
    print("Too many brackets needed")
    restore()
    return
end

sleep(delay*1000) 

if bookends == 1 then bookend() end

x_stop = h/3

if x == -1 then
    -- skip the other checks
elseif focus_strat == 1 then
    x = 0
    x_stop = x_start
elseif focus_strat == 2 then
    x = 0
elseif focus_strat == 3 then
    x_stop = x_start + delx
elseif focus_strat == 4 then
    x = x_start - delx
    x_stop = x_start
elseif focus_strat == 5 then
    x_stop = x_start
elseif focus_strat == 6 then
    x_stop = x_start + delx
    x = x_start - delx
end

while (x < x_stop) and focus_strat ~= 5 and x_start ~= -1 do -- capture the focus brackets up to the required x_stop
    refocus(x)
    X_bracket()
    x = dof.focus -- get actual x moved by cam
    last_x = x
    x = (x*(h*10 - 2*fl))/(h*10 - 2*x*10) -- position of next focus bracket
    if x <= last_x then -- can't continue
        print("breaking")
        break
    end 
end

if x ~= x_stop then refocus(x_stop) end

X_bracket()

if focus_strat == 0 or focus_strat == 2 then 
    refocus(h) -- take shot at h
    X_bracket()

    temp2 = h*(quality+2)
    refocus(temp2) -- take shoot at infinity blur quality
    X_bracket()   
end

if bookends == 1 then bookend() end

restore()