LBS (CHDK)

LBS.lua

--[[
Landscape Bracketing Script (LBS)

Capture 'perfect' focus brackets, with focus overlap defined in terms of defocus (CHDK) Circle of Confusion blur

Focus bracketing strategies are: current position to blur-defined infinity (X2INF); min camera focus to blur-defined infinity (Min2INF); H/x to infinity (H/x2INF);...
and Min focus to current focus position (Min2X).

Overlap, ie bracket to bracket, is definded in terms of the defocus (CoC) blur, eg CoC/2 means focus brackets 'touch' at a CHDK defocus blur of CoC/2. 

Exposure brackets may be taken at each focus step, using various schemes: 1Ev, 2Ev or 3Ev steps using -/+ or -/-- or +/++; one
ISO at 800 or 1600; or one (Zero Noise) exposure at +4Ev, +3Ev or +2Ev, auto from shadow exposure to an ETTR exposure, a wind bracket where the exposure stays the same...
but ISO and shutter speed are adjusted, ie to achieve a faster shutter; and a full auto.

You can check the camera's black level and set this value via the menu, eg put the lens cover on and run the script with the check black level option.

Black and White level sensitivity can be user set to Normal, Mediun or High. White level influences ETTR exposure insurance, ie high skewing the exposure away from 100% saturation.

You can also switch on Infinity Brackets that allows you to take an ETTR shot at the infinity focus position, eg for the sky, or capture a simulated ND bracket set, up to a 5 ND, or both.

Use Bookends to differentiate the captured bracket set in post (reccomended). Note the ND sub bracket will be bookended as well.

The script will pause and display info about the option you have selected. You can refocus, with the script recalculating number of brackets...
or telling you the infinity defocus blur if you are positioned beyond the hyperfocal.

When the script is paused you can change the shutter; however, don't try and change aperture or focal length, as the script will terminate in a controlled way.

You can switch off the screen during bracketing (recommended).

Press Half Shutter to run the script or MENU to exit script.

The script should run on most CHDK cameras, but bits of the code may need tweaking, eg to account for camera specific buttons.

Rev 1.1865
June 2022
Garry George

@chdk_version 1.6
@title LBS
@subtitle Focus Stuff
# focus_strat = 0 "Focus logic?" {None X2INF Min2INF H/x2INF Min2X}
# hfrac = 0 "H start" {H H/3 H/5 H/7 H/9}
# overlap = 0 "Overlap at" {CoC 2CoC/3 CoC/2}
# quality = 2 "Infinity quality?" {CoC/2 CoC/3 CoC/4}

@subtitle Exposure Stuff
# delta = 0 "Exposure logic?" {None 1Ev 2Ev 3Ev 800 1600 ZN4 ZN3 ZN2 A:x>H Wind A:S>H}
# logic = 0 "Bracketing logic?" {0/-/+ 0/-/-- 0/+/++}
# hilit = 0 "Over X Sensitivity" {Normal Medium High}
# bp = 0 "Black Level Sensitivity" {Normal Medium High}
# sky = 0 "Inf Bracketing?" {None Sky NDSim Both Auto}
# NDF = 1 "ND (Ev) value" [1 5]

@subtitle Other Stuff
# delay = 3 "Script Delay (s)" [0 5]
# bookends = 1 "Bookends?" {No Yes}
# screen_off = 1 "Screen off?" {No Yes}
# bplevel = 0 "Check Black Level?" {No Yes}
# bpval = 30 "Black Level" [0 200]
--]]

capmode = require("capmode")
props=require'propcase'
bi = get_buildinfo()

if (bi.platform == "m3") then 
    print("Doesn't run on M3")
    sleep(3000)
    return
end

if bi.platform == "s95" then
    set_exit_key("display") 
--elseif bi.platform == "???" then -- add additional camera specific exit keys here
    --set_exit_key("display") 
else
    set_exit_key("right") -- default exit key
end

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 and pupil magnification

function restore() -- called at script termination
    exit_alt()
end

function my_restore()
    if x_start == -1 then refocus(1000000) else refocus(x_start) end
    set_user_tv96(s_start)
    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())
    set_lcd_display(1)
    cls()
    exit_alt() -- just in case
    sleep(1000) -- just in case
end

function set_up()
    current_focus_mode = get_focus_mode() 
    current_mode = capmode.get_name()
    
    if capmode.get_name() ~= "M" then 
        print("Switch to M mode")
        sleep(2000)
        exit_alt()
        return false
    end

    if current_focus_mode ~= 1 then
        print("Switch to MF mode")
        sleep(2000)
        exit_alt()
        return false
    end

    press("shoot_half")
    repeat sleep(10) until get_shooting()
    
        dof = get_dofinfo()
        x = dof.focus
        x_start = x
        fl = fmath.new(dof.focal_length,1000) -- focal length in mm (real)
        s = get_prop(props.TV)
        s_start = s
        av = get_prop(props.AV)
        n = fmath.new(av96_to_aperture(av),1000) -- aperture number as a real
    
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())

    x_start = x
    xr = x

    base_h = (1000*fl*fl)/(n*dof.coc) 
    H = base_h + fl
    
    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 snap() -- single image capture
    press("shoot_half")
    repeat sleep(10) until (get_shooting())
        myshoot()
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
end

function bookend()
    set_user_tv96(960)
    set_av96_direct(get_max_av96())
    local ecnt = get_exp_count()
    shoot()
    set_user_tv96(s)
    set_av96_direct(av)
    repeat sleep(10) until (get_exp_count() ~= ecnt)
end

function refocus(xx)
    set_focus(xx)
    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 or delta == 11 then
        shot_histo_enable(1)
        myshoot()
        sleep(100)
        if bp == 1 then
            bp = 3
        elseif bp == 2 then
            bp = 9
        end
        hilit2 = hilit
        if hilit2 == 1 then
            hilit2 = 3
        elseif hilit2 == 2 then
            hilit2 = 6
        end
        do
            local bpl = bpval
            local lower = 1023 - hilit2
            local test=get_histo_range(lower,1023)
            local test2 = get_histo_range(bpl,bpl+bp)
            step = 1
            while test > 0 do
                set_tv96_direct(s + 96 * 2 * step)
                myshoot()
                sleep(100)
                test=get_histo_range(lower,1023)
                step = step + 1
            end
            if delta == 11 then
                step = 1
                while test2 > 0 do
                    set_tv96_direct(s - 96 * 2 * step)
                    myshoot()
                    sleep(100)
                    test2=get_histo_range(bpl,bpl+bp)
                    step = step + 1
                end
            end
        end
        shot_histo_enable(0)
    elseif delta == 10 then -- 3Ev ISO uplift from a lowish ISO base
        snap()
        set_tv96_direct(s+96*3)
        local svt = get_sv96()
        set_sv96(svt+(3*96))
        snap()
        set_sv96(svt)
    end
    set_tv96_direct(s)
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
end

function set_ETTR(n)
    histo={}
    count = 0

    if bi.platform == "g7x" then -- adjust histogram saturation bin
        top = 235
    --elseif bi.platform == "???" then -- add additional cameras here
        --top = ?
    else
        top = 255
    end

    set_user_tv96(s) -- current exposure
    press("shoot_half")
    repeat sleep(10) until get_shooting()
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
    histo,total=get_live_histo()
    for j = (top-n),top, 1 do 
        count = count + histo[j] 
    end
    if count > 0 then -- over exposed
        i = 0
        repeat
            i=i+96
            count = 0
            set_user_tv96(s+i)
            press("shoot_half")
            repeat sleep(10) until get_shooting()
            release("shoot_half")
            repeat sleep(10) until (not get_shooting())
            histo,total=get_live_histo()
            for j = (top-n),top, 1 do 
                count = count + histo[j] 
            end
        until count <= 0
    end
    return
end

function num_b (xx)
    local xc = xx
    local HH = H:int()
    if xx < 1 then -- at infinity
        return 1
    end
    if focus_strat == 0 then -- no focus bracketing requested
        return 1
    elseif (3*xc < HH) then
        local i = 0
        repeat
            xc = ((xc*(h-fl))/(fl+h-2*xc)):int()
            i = i + 1
        until 3*xc >= HH
        return (i + 1)
    elseif (xx < HH) then
        return 2
    else
        return 1
    end
end

-- Main section

if not set_up() then
    print("Can't run script")
    return -- exit script
end

if bplevel == 1 then
    shot_histo_enable(1)
    jj = 0
    myshoot()
    repeat
        test2 = get_histo_range(jj,jj)
        jj = jj + 1
    until test2 > 0
    shot_histo_enable(0)
    print("Black Level = "..jj-1)
    sleep(4000)
    return
end

-- Adjust the overlap h if required
h = base_h -- 'short' hyperfocal, ie H = h + fl

if overlap == 1 then -- adjust h to achieve the requested overlap, ie 'touching' at 2*CoC/3 or CoC/2
    h = (h*3)/2
elseif overlap == 2 then
    h = 2*h
end

H = h + fl -- 'full' hyperfocal as measured 'from the lens'

x_stop = (H/3):int()

if ((focus_strat == 2) or (focus_strat == 4)) then -- move to minimum focus
    x = 10
    xr = refocus(x)
    x = xr
elseif focus_strat == 3 then
    x = (H/(2*hfrac+1)):int()
    xr = refocus(x)
    x = xr
end

-- Keep all DoF calculations in request-space, to limit build up of image to image CHDK-Canon errors
bracks = num_b(xr)

if focus_strat == 0 then bracks = 1 end

if focus_strat == 4 then
    x_stop = x_start
    if x_stop > (H/3):int() then 
        print("Too far away")
        return
    end
    bracks = num_b(xr) - num_b(x_stop)
end

if focus_strat == 0 then
    print("@:"..x.."mm")
else
    print("At least "..bracks.." focus steps")
    print("@:"..x.."mm")
    if focus_strat == 4 then
        print("Stop@:"..x_stop.."mm")
    else
        print("H@:"..H:int().."mm")
    end
end

print("HS 2 run: MENU 2 exit")
dof = get_dofinfo() -- get current focal length and aperture values
fl_check = dof.focal_length
av_check = dof.aperture

if (focus_strat == 1 or  focus_strat == 0) then last_x = 0 else last_x = x end

repeat

    dof = get_dofinfo() -- Note the following checks may not work on all cameras: so don't change focal length or aperture ;-)
    if fl_check ~= dof.focal_length then
        print("FL changed!")
        sleep(2000)
        return
    end
    if av_check ~= dof.aperture and get_alt_mode() then
        print("Aperture changed!")
        sleep(2000)
        return
    end

    if focus_strat == 1 then
        if last_x ~= dof.focus then
            last_x = dof.focus
            if last_x == -1 then
                print("@ infinity")
            elseif last_x >= H:int() then 
                if last_x > 0 then
                    blur = ((dof.coc*H)/last_x):int()
                else
                    blur = 0
                end
                print("@:"..last_x.."mm/InfBlur="..blur.."um")
            else
                bracks = num_b(last_x) + 1
                print("@:"..last_x.."mm/#steps="..bracks)
            end
        end
    elseif focus_strat == 0 then
        if last_x ~= dof.focus then
            last_x = dof.focus
            if last_x == -1 then
                print("@ infinity")
            elseif last_x >= H:int() then 
                if last_x > 0 then
                    blur = ((dof.coc*H)/last_x):int()
                else
                    blur = 0
                end
                print("@:"..last_x.."mm/InfBlur="..blur.."um")
            else
                print("<H@:"..last_x.."mm")
            end
        end
    end

    dof = get_dofinfo()
    fl_check = dof.focal_length
    av_check = dof.aperture
    wait_click(500)
    if is_key("set") then 
        print("HS 2 run: MENU 2 exit")
        last_x = -9
        console_redraw() 
    end

    if is_key("menu") then 
        my_restore()
        return 
    end

until is_key("shoot_half") and get_alt_mode() 

press("shoot_half")
repeat sleep(10) until get_shooting()
    s_start = get_prop(props.TV)
    s = s_start
    set_user_tv96(s_start)
release("shoot_half")
repeat sleep(10) until (not get_shooting())

xr = refocus(last_x)
x = xr

t1=os.time()

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

if focus_strat == 0 then -- take requested exposues only
    X_bracket()
else
    im = 0

    while (xr < x_stop) and (xr > 0) do -- capture the focus brackets up to the required x_stop
        im = im + 1
        print(im.."/"..bracks..": "..x.."mm")
        X_bracket()
        if 2*xr >= H:int() then break end
        xrn = ((xr*(h-fl))/(fl+h-2*xr)):int()
        if xrn == xr then xrn = xr + 1 end
        xr = xrn
        x = refocus(xr)
    end

    if focus_strat ~= 4 then
        if xr == -1 then
            im=im+1
            print(im.."/"..bracks..":INF")
            X_bracket() 
        else -- take an image at H and the infinity blur position
            temp = H:int()
            temp2 = refocus(temp) -- take shot at the base hyperfocal
            im=im+1
            print(im.."/"..bracks..": "..temp2.."mm")
            X_bracket()
            temp2 = (H*(quality+2)):int()
            temp2 = refocus(temp2) -- take shoot at the selected infinity blur
            im=im+1
            print(im.."/"..bracks..": "..temp2.."mm")
            X_bracket() 
        end  
    end
end

if (sky == 2 or sky == 3) then -- capture an ND sim bracket subset
    if bookends == 1 then bookend() end
    print("ND brackets")
    set_tv96_direct(s_start)
    if NDF == 1 then
        i = 2
    elseif NDF == 2 then
        i = 4
    elseif NDF == 3 then
        i = 8
    elseif NDF == 4 then
        i = 16
    else
        i = 32
    end
    for j = 1, i do 
        snap()
    end
    if bookends == 1 then bookend() end
end

if (sky == 1 or sky == 3) and focus_strat ~= 4 then -- Take a sky ETTR shot
    print("Sky bracket")
    hilit2 = hilit
    if hilit2 == 1 then
        hilit2 = 3
    elseif hilit2 == 2 then
        hilit2 = 9
    end
    set_ETTR(hilit2)
    press("shoot_half")
    repeat sleep(10) until get_shooting()
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
    myshoot()
end 

if sky == 4 and focus_strat ~= 4 then -- Take a sky auto exposure bracket set
    shot_histo_enable(1)
    myshoot()
    hilit2 = hilit
    if hilit2 == 1 then
        hilit2 = 3
    elseif hilit2 == 2 then
        hilit2 = 6
    end
    do
        local lower = 1023 - hilit2
        local test=get_histo_range(lower,1023)
        step = 1
        while test > 0 do
            set_tv96_direct(s + 96 * 2 * step)
            myshoot()
            test=get_histo_range(lower,1023)
            step = step + 1
        end
    end
    shot_histo_enable(0)
end

if bookends == 1 then bookend() end

my_restore()