Hand Held Bracketing Script

HHB.Lua

--HHB Script Release 1.75

--[[
********************************************************************************************
This script attempts to capture 'the best' bracket sequence when hand holding.
The bracketing scheme is based on ISO shifting as well as time shifting.
The general strategy being to time shift from the highlights at the lowst ISO you can, and ISO shift from the shadows from the lowest Tv you can, at ISO 100. That is try and maximise photon capture, ie for the highest DR.
Note pushing ISO too far is pointless, as once above a critical level, Canon cameras go into ISO invariant zone (varies with camera) and overall DR falls with no increase in (read) noise.
You should also be high enough to be above the 'pattern noise', but not too high.
On a 5D3 a figure of 6400 seems to work well, on an EOSM, say, maybe try 1600 or 3200.
The script is triggered by a 3+ sec half shutter press. The script will give user feedback as requested.
The script's menu allows you to select a 0, 2 or 5 second delay.
To get the best workflow, switch ETTR on and use ETTR to set the base exposure. 
Irrespective of using ETTR, the base exposure should always be the exposure set for the highlights.
You can select the min shutter yourself in manual mode, the script uses the ETTR min even if you don't ETTR. 
In auto mode (also ensure you select FF or Crop to suit your camera) the script will adjust the min shutter according to your FL. 
You can also set an explicit min shutter for Auto mode to account for WA lenses, ie auto 1/FL too low.
The script will take either 3 or 6 brackets, according to the scene and your menu choices.
That is (3 x ISO brackets from the slowest shutter, always) plus [(3 x (highlight) time brackets if possible) or (3 x high ISO 'noise' brackets if requested)]
The 3 high ISO 'noise' brackets can be either at 1/3Ev or 0Ev apart: down from the menu set max ISO
The script can be switched off (disabled) via its menu.
The script will run in LV on non-LV mode.
The brackets need to be post processed, eg through LR HDR Merge, Photomatix or with LR/Enfuse or some other app that handles exposure bracketing, or blended with layer masks.
The script checks if the lens reports FL and adjusts accordingly. So the script can be used with manual lenses that don't report FL, but ensure you set ETTR min to suit your lens.
The script 'remembers' menu settings at camera close, so you will only need to set them once: only change things as required.

Garry George
Feb 2018
www.photography.grayheron.net
********************************************************************************************
--]]

require("config")

max_iso = 0 -- Set in menu
first_pass = false
second_pass = false
reset = false
base_shutter_apex = 0
base_iso_apex = 0
count = 0
options0 = {"ON", "OFF"}
options1 = {"Auto", "Manual"}
options2 = {"0 delay", "2s delay", "5s delay"}
options3 = {"FF Sensor", "Crop Sensor"}
options4 = {"1600", "3200","6400"}
options5 = {"Auto","1/30","1/60"}
options6 = {"None", "Audio","Led", "Both"}
options7 = {"OFF", "Time only", "Time/Noise", "Noise only"}
options8 = {"0Ev", "1/3Ev"}
min_shutter_value =0
min_shutter_apex = 0
timer_running = false
time_pressed = 0
run_HHB = false
beeped = false
good_to_go = false

function HH_bracket(arg) -- note this function is called regularly by the shoot_task event handler and does all the main work
    
    if HHB_menu.submenu["Turn Script on and off"].value == "ON" then good_to_go = true else good_to_go = false end -- track the script's on/off state 

    if good_to_go and timer_running and (not beeped) and (dryos.ms_clock - time_pressed > 3000) then -- give user feedback if requested
        if HHB_menu.submenu["User feedback"].value == "Audio" or HHB_menu.submenu["User feedback"].value == "Both" then beep() end
        if HHB_menu.submenu["User feedback"].value == "Led" or HHB_menu.submenu["User feedback"].value == "Both" then led_blink() end
        beeped = true -- so don't beep again
    end

    if good_to_go and not run_HHB then -- keep track of min shutter speed
        if lens.focal_length == 0 then menu.set("Hand Held Bracketing", "Min Shutter options", "Manual") end -- handle lenses that don't report FL, but ensure ETTR min shutter set correctly
        if HHB_menu.submenu["Min Shutter options"].value == "Auto" then -- set ETTR automatically based on focal length and min hand holding shutter set in script's menu
             local x = lens.focal_length
             if HHB_menu.submenu["Sensor Type"].value == "Crop Sensor" then x = x*1.6 end -- account for crop sensor
             x = 8*(7+math.ceil(math.log(x)/math.log(2)))
                 if x < 96 and HHB_menu.submenu["Your min hand holding limit"].value == "1/30" then
                    x = 96
                 elseif x < 104 and HHB_menu.submenu["Your min hand holding limit"].value == "1/60" then
                    x = 104
                 end
             menu.set("Auto ETTR","Slowest shutter", x) -- set slowest ETTR shutter to FL-informed value, ie 1/FL guidance + your min hand holding limit (1/30 or 1/60)
        end
             min_shutter_value = menu.get("Auto ETTR","Slowest shutter",1)
             min_shutter_value = 1/(2^(min_shutter_value/8 - 7)) -- set min shutter in seconds based on ETTR setting
    end

    if good_to_go and run_HHB then -- capture brackets

    -- Now manage the three phases

            if first_pass then -- do ISO bracketing, 'up' from the min (hand held) shutter, starting at ISO 100, in an attempt to cover the shadow end
                first_pass = false -- so don't do first pass again in this bracketing sequence     
                max_iso = tonumber(HHB_menu.submenu["Max ISO"].value)
                second_pass = true -- do a second pass when ready
                reset = false -- but don't do a reset yet, ie only after a second pass attempt
                base_iso_apex = camera.iso.apex -- get base ISO value in APEX units, ie the ISO set for the highlights
                base_shutter_apex = camera.shutter.apex -- get base shutter speed, ie the shutter value used for the highlights in APEX units    
                menu.set("Shoot", "Advanced Bracket", 0) -- switch advanced bracketing off, just in case it's on'
                camera.shutter.value = min_shutter_value -- get ready to ISO bracket from min shutter position
                min_shutter_apex = camera.shutter.apex -- get this shutter in APEX units
                camera.iso.apex = 5 -- set to ISO 100
                if HHB_menu.submenu["Delay?"].value == "2s delay" then
                    msleep(2000) -- inject a 2 sec delay
                elseif HHB_menu.submenu["Delay?"].value == "5s delay" then
                    msleep(5000) -- inject a 5 sec delay
                end -- else no delay
                count = dryos.shooting_card.file_number -- get current file counter before we start bracketing
                camera.shoot() -- capture the 3 ISO brackets from the min shutter
                camera.iso.value = max_iso
                camera.shoot()
                camera.iso.apex = (camera.iso.apex + 5)/2
                camera.shoot()
                return true
            end

        -- Do a time or 'noise' bracket pass, from the highlight shutter time starting position or high ISO level
            if second_pass and (dryos.shooting_card.file_number - count == 3) then -- do a second time bracket pass from the highlights, if possible
                second_pass = false
                camera.shutter.apex = base_shutter_apex -- set shutter to base shutter speed, ie as set for the highlights
                camera.iso.apex = base_iso_apex -- set to base ISO, ie as set for the highlights
                if base_shutter_apex > min_shutter_apex and (HHB_menu.submenu["2nd Pass Options?"].value == "Time only" or HHB_menu.submenu["2nd Pass Options?"].value == "Time/Noise") then -- can do 3 time brackets from the highlights
                    camera.shoot()
                    camera.shutter.apex = min_shutter_apex
                    camera.shoot()
                    camera.shutter.apex = camera.shutter.apex + (base_shutter_apex - min_shutter_apex)/2
                    camera.shoot()
                elseif HHB_menu.submenu["2nd Pass Options?"].value == "OFF" then 
		        -- no second pass requested
		        elseif HHB_menu.submenu["2nd Pass Options?"].value == "Noise only" or HHB_menu.submenu["2nd Pass Options?"].value == "Time/Noise"  then -- do some high ISO 'noise' brackets at min shutter
		            camera.shutter.iso = min_shutter_apex
		            local delta_ev = 0
		            if HHB_menu.submenu["Noise Ev delta"].value == "1/3Ev" then delta_ev = 0.33 end
                    camera.iso.value = max_iso
                    camera.iso.apex = camera.iso.apex - delta_ev
                    camera.shoot()
                    camera.iso.apex = camera.iso.apex - delta_ev
                    camera.shoot()
                    camera.iso.apex = camera.iso.apex - delta_ev
                    camera.shoot()
                end
                reset = true
                return true
            end

        -- Are we ready to reset?
            if reset then -- tidy up
                reset = false
                camera.shutter.apex = base_shutter_apex -- reset to initial state
                camera.iso.apex = base_iso_apex -- reset to initial state
                count = 0
                menu.set("Shoot", "Advanced Bracket", 0) -- ensure advanced bracketing off so you can ETTR
                if timer_running and (not beeped) then -- give user feedback if requested
                    if HHB_menu.submenu["User feedback"].value == "Audio" or HHB_menu.submenu["User feedback"].value == "Both" then beep() end
                    if HHB_menu.submenu["User feedback"].value == "Led" or HHB_menu.submenu["User feedback"].value == "Both" then led_blink() end
                end
                run_HHB = false -- signal end of bracketing sequence to event handler
                return true
            end
            return true  -- keep watching out
    end
    return true
end

function test4key(key)
    if key == KEY.HALFSHUTTER and good_to_go and (not timer_running) and (not run_HHB) then -- note assumes the shoot_task runs at least once following camera start
        timer_running = true -- start looking for half shutter long press
	time_pressed = dryos.ms_clock
        beeped = false
        return false -- steal key press
    elseif key == KEY.UNPRESS_HALFSHUTTER and good_to_go and timer_running and (not run_HHB) then
        if dryos.ms_clock - time_pressed > 3000 then -- 3 sec plus half shutter press, so start HH bracketing
           run_HHB = true -- OK to run the main script
           timer_running = false -- stop looking for a long press
           first_pass = true
           return false -- steal key press
        else -- less than 3 seconds so handle as a normal half shutter unpress
           timer_running = false
           return true
        end
    else -- must be a normal key press
        return true
    end
end

event.keypress = test4key
event.shoot_task = HH_bracket

HHB_menu = menu.new
{
    parent = "Shoot",
    name = "Hand Held Bracketing",
    help = "Start at exposure for the highlights",
    submenu =
    {
        {
            name = "Turn Script on and off",
            help = "Does what it says",
            choices = options0,
        },
        {
            name = "Min Shutter options",
            help = "Auto means script sets ETTR min, manual means you do",
            help2 = "For manual, set min in ETTR menu",
            choices = options1,
        },
        {
            name = "Sensor Type",
            help = "Full Frame or Crop 1.6?",
            choices = options3,
        },
        {
            name = "Delay?",
            help = "Injects the requested delay before bracketing",
            help2 = "Switch off Canon delays",
            choices = options2,
        },
        {
            name = "Max ISO",
            help = "Make sure Canon Auto Max ISO is the same",
            choices = options4,
        },
        {
            name = "2nd Pass Options?",
            help = "For noise options choose delta Ev",
            help2 = "if Time/Noise then do Noise if can't do Time",
            choices = options7,
        },
        {
            name = "Noise Ev delta",
            help = "Delta Ev ISO bracket",
            choices = options8,
        },
        {
            name = "Your min hand holding limit",
            help = "Your hand holding shutter speed limit",
            help2 = "Useful when in Auto mode to override 1/FL for WA lenses",
            choices = options5,
        },
        {
            name = "User feedback",
            help = "To help with 3s half shutter and indicate bracket end",
            choices = options6,
        }
    }
}

config.create_from_menu(HHB_menu) -- keep a track of the script's menu state at camera close