M3 Focus & Exposure Bracketing

M3 Brackets.lua

--[[
@title M3 Bracketing: Focus & Exposure
@chdk_version 1.5
#mode = 0 "Mode" {Off X2INF Min2INF}
#bracket = 0 "Exposure bracket?" {None +4Ev +3Ev +2Ev 2(+2Ev) 3(+2Ev) ISO1600 auto}
#infinity = 3 "Infinity focus" [2 4]
#overlap = 15 "Overlap (um)" [5 20]
#sleep_time = 2 "Delay (s)"
#bookends = 1 "Bookends?" {No Yes}
#screen_off = 0 "Screen off?" {No Yes}
#t = 0 "x for Thickness (mm)"
#hilit = 20 "% histo HiLit" [5 30]
#lens = 0 "Get lens name?" {No Yes}

Release 1.62

Note: only tested on EFM lenses

photography.grayheron.net
July 2020
--]] 

capmode = require("capmode")
bi = get_buildinfo()

if (bi.platform ~= "m3") then error('Only runs on M3') end
press("shoot_half")
repeat sleep(10) until get_shooting()
dof = get_dofinfo()
f = dof.focal_length -- in microns
F = f / 1000 -- focal length in mm
s = get_tv96()
av = get_av96()
release("shoot_half")
repeat sleep(10) until (not get_shooting())
n = av96_to_aperture(get_user_av96()) -- N*1000
H = (f / 1000 + (f * f) / ((n * overlap))) -- for overlap control, in mm
steps = 1

function get_focus_distance_upper()
    local x = -1
    if (bi.platsub == "101a") then
        x = peek(0x00244916, 2)
    elseif (bi.platsub == "120f") then
        x = peek(0x0024495A, 2)
    else
        error('Not 101a or 120f')
    end
    return x
end

function lens_name()
    local get_lens_name_fn = 0xfc2f3fd5
    if (bi.platsub == "101a") then get_lens_name_fn = 0xfc2f3fc3 end

    if call_event_proc('System.Create') == -1 then error('Unknown Error') end

    local ppname = call_event_proc('AllocateMemory', 8)

    if ppname == -1 or ppname == 0 then error('Unknown Error') end

    local plen = ppname + 4
    poke(ppname, 0)
    poke(plen, 0)
    local status = call_func_ptr(get_lens_name_fn, ppname, plen)
    local pname = peek(ppname)
    local len = peek(plen)
    call_event_proc('FreeMemory', ppname)
    if ppname == -1 or ppname == 0 then error('Unknown Error') end
    local i = 0
    local t = {}
    while i < len do
        local c = peek(pname + i, 1)
        if c == 0 then break end
        table.insert(t, string.char(c))
        i = i + 1
    end
    local name = table.concat(t)
    return name
end

function restore()
    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)
    exit_alt()
end

function get_focus_distance_lower()
    local x = -1
    if (bi.platsub == "101a") then
        x = peek(0x00244918, 2)
    elseif (bi.platsub == "120f") then
        x = peek(0x0024495C, 2)
    else
        error('Not 101a or 120f')
    end
    return x
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
    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(100)
    release("shoot_half")
    repeat sleep(10) until (not get_shooting())
    return true
end

function refocus_to(xx) -- returns requested focus distance in cm
    local current_x = get_focus_distance_lower() -- ie focus distance of current step that includes current_x
    local steps_total = 0
    local last_step_count = steps_total
    if xx < current_x then return -1 end -- don't use
    local last_x = current_x
    while current_x < xx do
        call_event_proc("EFLensCom.MoveFocus", steps, 1) -- move towards infinity
        steps_total = steps_total + steps
        sleep(25) -- for system to catch up
        current_x = get_focus_distance_lower()
        if (current_x ~= last_x) and (current_x < xx) then -- just went through an intermediate step change, ie not yet reached the step that covers xx
            last_x = current_x
            last_step_count = steps_total -- close enough
        end
    end
    -- now fine tune position
    local steps_back = ((current_x - xx) * (steps_total - last_step_count)) / (current_x - last_x)
    steps_back = steps_back/steps
    if steps_back ~= 0 then
        for i = 1, steps_back do call_event_proc("EFLensCom.MoveFocus", -steps, 1) end
    end
    sleep(25) -- for system to catch up
    current_x = get_focus_distance_lower()
    return current_x -- may not represent the actual position, but it's the best we can do on the M3
end

function myshoot()
    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 X_bracket()
    press("shoot_half")
    repeat sleep(10) until (get_shooting())
    set_tv96_direct(s)
    if bracket == 0 then
        myshoot()
    elseif bracket == 1 then
        myshoot()
        set_tv96_direct(s - 96 * 4)
        myshoot()
    elseif bracket == 2 then
        myshoot()
        set_tv96_direct(s - 96 * 3)
        myshoot()
    elseif bracket == 3 then
        myshoot()
        set_tv96_direct(s - 96 * 2)
        myshoot()
    elseif bracket == 4 then
        myshoot()
        set_tv96_direct(s - 96 * 2)
        myshoot()
        set_tv96_direct(s - 96 * 4)
        myshoot()
    elseif bracket == 5 then
        myshoot()
        set_tv96_direct(s - 96 * 2)
        myshoot()
        set_tv96_direct(s - 96 * 4)
        myshoot()
        set_tv96_direct(s - 96 * 6)
        myshoot()
    elseif bracket == 6 then
        local iso = get_iso_mode()
        set_iso_mode(100)
        myshoot()
        set_iso_mode(1600)
        myshoot()
        set_iso_mode(iso)
    elseif bracket == 7 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

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

-- Main Section

if lens == 1 then
    print(lens_name())
    return
end

if t > 0 then -- calculate lens thickness from credit card measurement (assumes n = 3)
    w = 223 -- APS-C x 10 for EOS M3
    n = 3
    cc = 856 -- CC width x 10
    t = (10*t - ((10*F)*(cc*n + w))/(cc*n) - ((10*F)*(cc*n + w))/w)/10
elseif lens_name() == "EF-M11-22mm f/4-5.6 IS STM" then -- calculate lens thickness from manufacturer's data
    -- add other lenses as required, ie replace the following for your lens
    -- For the above lens, 300 is the lens max magnification x 1000, ie from manufacturer's data or your measurement
    -- 22000 is the lens maximun zoom, or the prime, focal length in microns
    -- 150 is the lens minimum focus distance (mm), ie from manufacturer's data or your measurement
    m = (300 * f) / (22000)
    t = (F * (1000 + m) * (1000 + m))
    t = 150 - t / (1000 * m) -- this is an estimate of the spilt thin lens thickness (mm)
    --[[
 elseif lens_name() == "your lens" then
    m = (max_mag? * f) / (max_fl?) -- where max_mag? is the max magnification x 1000 and max_fl? is the maximum focal length of your lens
    t = (F*(1000+m)*(1000+m))
    t = min_fd? - t/(1000*m) -- where min_fd? is the minimum focus distance of your lens
    ]]
else
    t = 0
end
print("t="..t)
if screen_off == 1 then set_lcd_display(0) end

set_up()

if bookends == 1 then bookend() end

if mode == 0 then
    X_bracket()
    if bookends == 1 then bookend() end
    restore()
    return
end

if mode == 2 then
    call_event_proc("EFLensCom.FocusSearchNear")
    sleep(50)
end

sleep(sleep_time * 1000)

x = get_focus_distance_lower() -- current x estimate in cm
q = (x*10 - t)
u = imath.sqrt(q*(q-4*F)*1000)/1000
u = (q + u)/2 -- estimate of distance from split thin lens 'front principal' in mm

X_bracket()

while (u < H/3) do -- capture the focus brackets up to H/3
    new_u = (2 * F * F - 3 * F * u + H * u) / (F + H - 2 * u) -- estimate position of next focus bracket in mm. From 'Ins & Out of Focus' by Merklinger
    if (new_u - u) < 10 then new_u = u + 10 end -- just in case
    u = new_u
    x = (100*u + 100*F + (100*F*F)/(u-F) + 100*t) / 1000 -- next focus bracket estimate from sensor plane in cm
    print(refocus_to(x) .. "cm")
    X_bracket()
end

if u < infinity*H then
    print(refocus_to(((F*F)/(H-F) + F + t + H) / 10) .. "cm")
    X_bracket()
    print(refocus_to(((F*F)/(infinity*H-F) + F + t + infinity*H) / 10) .. "cm")
    X_bracket()
end

if bookends == 1 then bookend() end

restore()