CHDK firmware hack discussion (10)

Started Jun 1, 2007 | Discussions thread
Russel_Sprouts
Regular MemberPosts: 257
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Re: It works! Need more help PLZ
In reply to Fragglerock, Jun 7, 2007

Fragglerock wrote:

I wrote a script to shoot clash.
camera shoots
until the nomber of shoots is ok. Between 2 shoots there is a pause
which is corresponding to exposure duration + 20 % time.

Hey, fraggle, how did you arrive at the 20% safety margin?
Observation? Just a guess?
In any event, for taking 15sec exposures, it's pretty accurate.

For my own use, I wrote a "lightning" script with hardcoded values.

FYI, outcommenting the PRINT statement within the loop seemed to shave off 100ms. (Try 10 print statements without sleep delays between them -- you should find that they take 1000ms total to exectue)

@title lightning: 15s nonstop
rem pause between shots must
rem accomodate darkframe delay
print "recommended cam setup:"
sleep 1200
print "manual+INFINITY focus"
sleep 1200
print "full WIDE zoom"
sleep 1200
print "Av 4.5 + Tv 15sec"
sleep 1200
print "flash OFF"
sleep 3000
print "turn LCD review OFF"
sleep 300
print "turn LCD review OFF"
sleep 300
print "turn LCD review OFF"
sleep 300
print "turn LCD review OFF"
sleep 1500
print "Interval shooting..."
print "until you interrupt it"
sleep 1800
for i=1 to 999
rem print "shooting #", i
click "shoot_full"
sleep 35000
next i
end

The script takes 35seconds to produce each 15sec exposure
(15/35 = shutter is open 42.9% of the time)

That's "less efficient coverage" than coverage produced by the "many many 1sec continuous shots" ligntning script shown in the wiki... but I much prefer the approach of using a long shutter.

I also prefer (instead of scripting parameters) the freedom to interrupt the script to quickly change f-stop. If the lightning gets too close (or zoom is used) photos too often get overexposed if the aperture hasn't been stopped down.

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