Get Brackets (CHDK)

Get Brackets.lua

--[[
Capture 'Perfect' focus brackets, with focus overlap defined in terms of defocus (CHDK Circle of Confusion (CoC)) blur

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).
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
None means that requested exposures will only be captured at the current focus point

Additional exposure brackets may be taken at each focus step, using various schemes: 1Ev, 2Ev or 3Ev steps using -/+ or -/-- or +/++; one iso-invariant at
ISO at 800 or 1600; or one (Zero Noise) exposure at +4Ev, +3Ev or +2Ev or auto from a shadow exposure

Use Bookends to help differentiate bracket set in post (reccomended)
Option to switch LCD screen off during shooting
Script will pause and display predicted number of focus brackets and, if requested, the infinity focus distance. Do a Full Shutter press to terminate or Half Shutter to run the script.
If you get an error message, try resetting focus as this is the usual cause

Tested on an S95, G5X, G7X and a G1X

For the EOS M3 version goto: https://chdk.fandom.com/wiki/Landscape_Focus_Bracketing_:_perfect_near_to_far_focus_brackets

Rev 1.9286211
August 2020
Garry George

@chdk_version 1.5
@title Get Brackets
@subtitle Focus Stuff
# 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]

@subtitle Exposure Stuff
# delta = 0 "Exposure delta?" {None 1Ev 2Ev 3Ev 800 1600 ZN4 ZN3 ZN2 Auto}
# logic = 0 "Exposure logic?" {0/-/+ 0/-/-- 0/+/++}
# hilit = 20 "% histo HiLit" [5 30]

@subtitle Other Stuff
# delay = 3 "Script Delay (s)" [0 5]
# bookends = 1 "Bookends?" {No Yes}
# screen_off = 0 "Screen off?" {No Yes}
--]]

capmode = require("capmode")

set_config_value(2151,0) -- switching these two off means we are measuring distance 'from the lens': ...
set_config_value(2152,0) -- ...this is the 'best' we can do without knowing the position of the front principal plane

function restore() -- called at script termination
    if done == 0 then
        if x_start == -1 then refocus(1000000) else refocus(x_start) end
        set_tv96_direct(s)
        set_av96_direct(av)
        press("shoot_half")
        release("shoot_half")
        if current_focus_mode ~= 1 then set_mf(0) end
        if (current_mode ~= "M") then capmode.set(current_mode) end
        set_lcd_display(1)
    end
end

function my_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(100)
    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)
    done = 1
end

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

    press("shoot_half")
    repeat sleep(10) until get_shooting()
    s = get_tv96()
    av = get_av96()
    if (current_mode ~= "M") then capmode.set("M") end
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
    dof = get_dofinfo()
    x = dof.focus
    x_start = x
    xr = x
    base_h = dof.hyp_dist -- that is without diffraction accounted for
    fl = dof.focal_length/100 -- focal length in mmx10

    if current_focus_mode ~= 1 then
        print("MF mode not set")
        done = 1
        return false
    end

    if x < 0 then
        print("Refocus as at infinity")
        done = 1
        return false
    end

    if x > base_h/3 and (focus_strat == 3 or focus_strat == 4 or focus_strat == 6) then
        print("Too far away")
        done = 1
        return false
    end
    
    return true
end

function myshoot() -- works inside X_bracket function
    local prevcnt=hook_shoot.count()
    local rawprevcnt=hook_raw.count()
    press'shoot_full_only'
    repeat sleep(10) until prevcnt ~= hook_shoot.count()
    release'shoot_full_only'
    repeat sleep(10) until rawprevcnt ~= hook_raw.count()
end

function bookend()
    set_tv96_direct(960)
    set_av96_direct(get_max_av96())
    local ecnt = get_exp_count()
    shoot()
    set_tv96_direct(s)
    set_av96_direct(av)
    repeat sleep(10) until (get_exp_count() ~= ecnt)
end

function refocus(xx)
    set_focus(xx)
    press("shoot_half")
    repeat sleep(10) until get_shooting()
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
    dof = get_dofinfo() -- update info
    return dof.focus
end

function X_bracket()
    press("shoot_half")
    repeat sleep(10) until (get_shooting())
    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()
    elseif delta == 9 then
        shot_histo_enable(1)
        myshoot()
        sleep(100)
        lower = 1024 - 1024*hilit/100
        test=get_histo_range(lower,1024)
        step = 0
        while test > 0 do
            step = step + 1
            set_tv96_direct(s + 96 * 2 * step)
            myshoot()
            sleep(100)
            test=get_histo_range(lower,1024)
        end
        shot_histo_enable(0)
    end
    set_tv96_direct(s)
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
end

-- Main section

done = 0

if not set_up() then 
    return -- exit script
end

-- Calculate the overlap h
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 umx1000
        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

x_stop = h/3

if focus_strat == 1 then
    x = 10
    xr = refocus(x)
    x_stop = x_start
elseif focus_strat == 2 then
    x = 10
    xr = refocus(x)
elseif focus_strat == 3 then
    x_stop = x_start + delx
elseif focus_strat == 4 then
    x = x_start - delx
    xr = refocus(x)
    x_stop = x_start
elseif focus_strat == 5 then
    X_bracket()
    if bookends == 1 then bookend() end
    my_restore()
    return
elseif focus_strat == 6 then
    x_stop = x_start + delx
    x = x_start - delx
    xr = refocus(x)
end

-- Keep all DoF calculations in request-space, to limit build up of image to image CHDK-Canon errors
if xr >= base_h then
    bracks = 2
else
    bracks = (-h*(xr-x_stop)+3*x_stop*xr)/(2*x_stop*xr)
    if bracks < 1 then bracks = 1 end
    if focus_strat == 0 or focus_strat == 2 then 
        bracks = bracks + 2
    end
end

print("# of Brackets = "..bracks)
if focus_strat == 0 or focus_strat == 2 then 
    print("Inf focus @: "..(base_h*(quality+2)).."mm")
end
print("Press HS or FS")

repeat
    wait_click()
until (is_key("shoot_half") or is_key("shoot_full"))

t1=os.time()
print("Bracketing Started")

if screen_off == 1 then set_lcd_display(0) end

if bookends == 1 then bookend() end
t1=(os.time()-t1)

if delay >= t1 then
    t1=delay-t1
    sleep(t1*1000) 
end

im = 0

while (xr <= x_stop) do -- capture the focus brackets up to the required x_stop
    if 2*xr >= h then break end
    im=im+1
    x = refocus(xr)
    print(im.."/"..bracks..": "..x.."mm")
    X_bracket()
    xr = (xr*(h*10 - 2*fl))/(h*10 - 2*xr*10) -- estimated position of next focus bracket
end

if focus_strat == 0 or focus_strat == 2 then 
    temp2 = refocus(base_h) -- take shot at the base hyperfocal
    im=im+1
    print(im.."/"..bracks..": "..temp2.."mm")
    X_bracket()
    temp2 = base_h*(quality+2)
    temp2 = refocus(temp2) -- take shoot at the selected infinity blur
    im=im+1
    print(im.."/"..bracks..": "..temp2.."mm")
    X_bracket()   
end

if bookends == 1 then bookend() end

my_restore()