I need to learn how to compensate the shorter shutter speed by what? aperture control? ISO control? other?
Can the camera do this automatically or do I need to set it in my script? Still a newby here...
-- read curent bv from scenefunction read_bv96() press("shoot_half") while get_prop(115)==0 do sleep(100) end bv=get_bv96() release("shoot_half") return bvend
-- Fast TV shooting-- Fast Tv mode is defined as a Tv mode where -- we try to attain a VERY fast shutter time (like 1/5000")-- by increasing ISO-- There is anyway a maximum value for ISOfunction fast_tv_shoot(bv, fast_tv, max_sv, offset)-- bv is the brightness we suppose have in the scene-- if bv=-1 this means we will have to meter ourselves-- fast_tv is the shutter time we would like to attain-- max_sv is the maximun sensibility we find acceptable -- offset is a fine-tuning for very fast exposures-- Possibile values for fast_tv-- 1245 = 1/8000-- 1149 = 1/4000-- 1053 = 1/2000-- 957 = 1/1000-- 861 = 1/500-- 765 = 1/250-- Possible values of max_sv-- 320 = ISO 50-- 388 = ISO 80-- 418 = ISO 100-- 514 = ISO 200-- 611 = ISO 400-- 707 = ISO 800-- 803 = ISO 1600-- Ixus 80 has fixed apertureav = 285 + offsetdbg("FAST TV")dbg("bv " .. bv)if bv==-1 then bv=read_bv96() dbg("metered bv " .. bv) -- offset measured brightnessend--if we shoot at fast_tv,tv=fast_tv-- resulting sv would besv = av + fast_tv - bv dbg("tv " .. tv)dbg("sv " .. sv)-- let's check if it's not too highif sv>max_sv then -- how much must we reduce sv? reduce = sv-max_sv -- same reduction must be added to tv tv=tv-reduce sv=max_sv dbg("Reduced: ") dbg("tv " .. tv) dbg("sv " .. sv)end -- it might also happen than sv goes too low-- arbitrary limit of 322 sv (abt ISO 50)if sv<322 then reduce = sv-322 tv=tv-reduce sv=322 dbg("INCREASED: ") dbg("tv " .. tv) dbg("sv " .. sv)end -- at last moment, set our parameters-- set shutter timeset_tv96_direct(tv) sleep(100)-- set ISOset_sv96(sv)sleep(100)shoot()writelog("FTV", "Shoot " .. get_exp_count() .. " ".. bv .. " " .. tv .. " " .. sv .. " " .. av)repeat sleep(100)until get_prop(206)==0end
function timestamp() h=get_time("h") m=get_time("m") s=get_time("s") return ( h .. ":" .. m .. ":" .. s)endfunction dbg(msg) -- uncomment for extra info il log file --print(msg)endfunction writelog(prefix, msg) ts=timestamp() print('###' .. prefix .. ' ' .. ts .. ' ' .. ' ' .. msg)end
-- min shutter 1/1000, max iso 100 fast_tv_shoot(-1, 957, 418, 24)
-- min shutter 1/2000, max iso 200 fast_tv_shoot(-1, 1053, 514, 32)
do you mean, "unmanned" underwater photography or just "normal" underwater photography?
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