Bracketing During Exposure

outslider

762

Re: Bracketing During Exposure

« Reply #10 on: 19 / December / 2011, 08:09:39 »

Advertisements

I'm not sure what does SD mean in SD bracketing, but I succesfully changed focus a few times during exposure. But remember, that each camera can work in different way. Moreover - the same camera might work different when you repeat experiment (while using zoom sx130 crashed soetimes at the begining of the zoom movement and sometimes at the end of the exposure and sometimes it took a few seconds more).

I have sx130is firmware 1.01c.

Maybe other way to perform your project is to use a few separated photos and then just add RAW files?

Logged

if (2*b || !2*b) {
cout<<question
}

Compile error: poor Yorick

Flutterbudget

10

Re: Bracketing During Exposure

« Reply #11 on: 19 / December / 2011, 17:45:57 »

Hey outslider...

SD stands for Subject distance, so basically it means focus. That's what I want to try doing, changing the focus during an exposure and seeing what the outcome is. You say you've done this a bit? What script did you use, how often was it successful and did it ever freeze/crash the camera?

Thanks,

!Noah!

Logged

outslider

762

Re: Bracketing During Exposure

« Reply #12 on: 19 / December / 2011, 18:21:33 »

Zoom - always crashed, focus - never. I have used exactly the same script as you have poseted above. I have also changed a few things including changing zoom to focus. I did some further changes and I did many different things, so I have no one specific script.

You need to do some experiments, especially about changes in zoom/focus range or time of move and so on...

Logged

if (2*b || !2*b) {
cout<<question
}

Compile error: poor Yorick

Flutterbudget

10

Re: Bracketing During Exposure

« Reply #13 on: 19 / December / 2011, 20:25:29 »

Ok. Trying...

Code: [Select]

--[[
Test zooming during long exposure.
 
1) Set camera to shoot a very long exposure (either M or Tv mode or
CHDK Tv override).
 
2) run the script
--]]
 
max_focus = get_focus_steps() - 1
 
if get_focus() ~= 0 then
  set_focus(0)
  sleep(5000)
end
 
press("shoot_half")
repeat
  sleep(1)
until get_shooting() == true
press("shoot_full")
sleep(100)
set_focus(max_focus)
 
repeat
  sleep(1)
until get_shooting() ~= true
 
release("shoot_full")
release("shoot_half")

How's that?

!Noah!

Logged

outslider

762

Re: Bracketing During Exposure

« Reply #14 on: 20 / December / 2011, 01:38:05 »

Well, I wasn't enough clear. You can't just replace set_zoom by set_focus()... Focusing mechanism is very fast. So it will focus without significant changes during exposure.

Try rather do something like:

Code: [Select]

max_f_steps=20 -- or whatever you want
for f=1,max_f_steps do
    set_focus(f)
    sleep(10)
    end

You should of course use 'shoot' command somewhere (or click("shoot_full")).

Just try to experiment, don't ask about pure solutions without experiments. Of course there is always some probability of camera damage while forcing hardware to do something it wasn't design to, but there's also no varranty, that somebody's else script will not blow away your camera;)

Logged

if (2*b || !2*b) {
cout<<question
}

Compile error: poor Yorick

Flutterbudget

10

Re: Bracketing During Exposure

« Reply #15 on: 02 / January / 2012, 23:02:42 »

Hey! Sorry I dropped out for a while. Got frustrated about this whole thing.

Anyway, I got a bit of help from my brother, who's actually done a bit of coding, and this is what he came up with. The code doesn't crash/damage the camera, but it sure doesn't bracket focus either.

Code: [Select]

--[[
Test zooming during long exposure.
 
1) Set camera to shoot a very long exposure (either M or Tv mode or
CHDK Tv override).
 
2) run the script
--]]

press("shoot_half")
repeat
  sleep(1)
until get_shooting() == true
press("shoot_full")
sleep(100)

for f=955,60000 do
    set_focus(f)
end

repeat
  sleep(1)
until get_shooting() ~= true

release("shoot_full")
release("shoot_half")

Outslider? You're sort of the expert here, so what do you think?

Also, please remember, I couldn't write a line of code to save my life. I need just a tad more help than's humanly possible.

Thanks,

!Noah!

Logged