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Shot Histogram Request

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Offline lapser

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Re: Shot Histogram Request
« Reply #170 on: 25 / March / 2013, 20:47:30 »
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Quote from: ahull on 25 / March / 2013, 20:08:20
lapser  :D - I could watch that all day (don't think I'd get paid though).
Thanks! It is pretty fascinating to see things with the help of technology in a way that was previously impossible. I was hoping for clear skies, but now I'm glad I got the clouds. It made the video more interesting.

I made a shorter time lapse with the SX50 right before the last video started. I wasn't expecting my external battery pack to last so long, so I wanted to start the G1X right before sunset. Anyway, here's the SX50 video:

http://www.youtube.com/watch?v=9_m2INhl2pE#ws

I also fired up the SX50 at first light from my tent using a Gorillapod in the vestibule. I must have been a little sleepy, because I had the camera in Manual Exposure mode. I discovered this at 2:25 into the video (after a cup of hot tea) and switched it to Aperture Priority while the script was running. The shot rate sped up and the pictures got much clearer. I think maybe setting the aperture with the script while in manual exposure mode was causing the aperture motor to move back and forth between each shot, or during the exposure. The clicking sound also changed in AP mode.

http://www.youtube.com/watch?v=ImpRHRcU5gY#ws
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EOS-M3_120f / SX50_100b / SX260_101a / G1X_100g / D20_100b
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Offline lapser

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Re: Shot Histogram Request
« Reply #171 on: 28 / March / 2013, 20:57:03 »
I decided to take another look at smoothing out the small exposure changes to avoid the "fluttering" effect in the dark parts of the picture that show up sometimes. My first attempt was in the shot meter routine (CHDK mod), but I realized it wasn't right. The exposure is set by the Lua script, so the proper place for smoothing is in the script, not the shot meter. So I took all the smoothing stuff out of the shot meter, and wrote some new smoothing into the script.

I added an input parameter to the script I call "smoothing". Basically, the script doesn't change the exposure as long as it's within plus or minus the smoothing factor. I.E. if smoothing = 16, then the exposure doesn't change until the photo is overexposed by 16, or underexposed by 16.

This seems to work, but it leaves the shot always over or under exposed by 16. So I added a test that if it's over or underexposed more than 2, I adjust it by 1. The idea is to bring the exposure slowly to the middle, proper exposure when it suddenly jumps. I'm not sure I'm explaining it properly, but here's the Lua code involved:
Code: (lua) [Select]
  --tvd is the change in exposure computed by the shot meter
  --you add tvd to the current exposure and use it for the next shot
  tx=0
  if(tvd>0)then
    if(tvd>2)then tx=1 end
    tvd=tvd-smooth
    if(tvd<0)then tvd=tx end
  elseif(tvd<0)then
    if(tvd<-2)then tx=-1 end
    tvd=tvd+smooth
    if(tvd>0)then tvd=tx end
  end
I'll try to test this tonight, weather permitting.

Here's a pretty interesting time lapse I did last night on Spencer's Butte:

http://www.youtube.com/watch?v=X2o6Cderq10#ws
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Offline lapser

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Re: Shot Histogram Request
« Reply #172 on: 29 / March / 2013, 01:29:17 »
Great sunset tonight. From the log files, it looks like the smoothing worked well. The only small mistake was using < instead of <= and > instead of >=
Code: (lua) [Select]
  tx=0
  if(tvd>0)then
    if(tvd>2)then tx=1 end
    tvd=tvd-smooth
    if(tvd<=0)then tvd=tx end -- changed to <=
  elseif(tvd<0)then
    if(tvd<-2)then tx=-1 end
    tvd=tvd+smooth
    if(tvd>=0)then tvd=tx end -- changed to >=
  end
Here's one of the pictures from the G1X:
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Offline ahull

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Re: Shot Histogram Request
« Reply #173 on: 29 / March / 2013, 10:44:14 »
Would your script work on my ancient SD300 (Ixus 40) and the latest SVN build ? If so, any chance of posting the full script, the results are pretty impressive. 
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Offline lapser

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Re: Shot Histogram Request
« Reply #174 on: 29 / March / 2013, 10:59:16 »
Quote from: ahull on 29 / March / 2013, 10:44:14
Would your script work on my ancient SD300 (Ixus 40) and the latest SVN build ? If so, any chance of posting the full script, the results are pretty impressive.
It requires a custom build I've been developing that adds a lot of functions to CHDK. I'd be interested in seeing if it does work on old cameras, so if you're game, let me know your firmware version and I'll post a build for you to try.
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Offline ahull

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Re: Shot Histogram Request
« Reply #175 on: 29 / March / 2013, 12:22:38 »
I have a couple of old cameras we can try, you could start with the Ixus 40, its on f/w 1.00k and I have just stuck
ixus40_sd300-100k-1.2.0-2653-full on an SD card, shoved it in a slightly butchered IXUS II WP-DC10 dive housing I got for next to nothing from ebay. (It fits in quite well with a little filing and a bit of blue tac, don't worry, I filed the case, not the camera  :P).

I'm running one of the existing sunset time lapse scripts and have stuck it at the end of the garden to give us a baseline to compare with. Don't expect results quite as good as the G1X  :D  Especially since it is the middle of the day here at the moment.


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Offline lapser

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Re: Shot Histogram Request
« Reply #176 on: 29 / March / 2013, 13:05:27 »
Quote from: ahull on 29 / March / 2013, 12:22:38
ixus40_sd300-100k-1.2.0-2653-full
OK, see if the attached CHDK build runs your current scripts.

My time lapse script switches to manual focus using:
post_levent_for_npt("PressSw1AndMF")

I think that may crash cameras without manual focus.

Does anyone know how to tell from a script if the camera has manual focus or not?

Without manual focus, I think you can just use set_focus, press shoot_half, and aflock, but newer cameras only set focus in manual focus mode. Anyway, maybe we can figure it out on your older cameras.

Let me know if the build works, and I'll post the script for you to test.
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Offline ahull

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Re: Shot Histogram Request
« Reply #177 on: 29 / March / 2013, 16:50:44 »
OK Good news, bad news time...

Good news is that that build loads OK on my camera (confused me slightly because it doesn't show the CHDK splash screen at startup, the first time,  so I thought it wasn't loading).

Good news,
I see the fancy new menu layout.
I can shoot DNG

Bad news, RawTherapee cant make sense of the .DNG file (I'll investigate this later, maybe try  DNG 1.1).
EDIT: Nope, and .CRW looks like nonsense as well. Neither RawTherapee nor UFRAW can make any sense of them, they look like a noise with a narrow horizontal band of dark colour about 1/4 of the way down from the top.
 
Good news, it runs the sunset timelapse script I used for the first test run.

More bad news, the internal SD card reader in my laptop suffered a fatal mechanical breakdown (i.e. the cheap'n nasty plasticky POS fell apart, and spat out a couple of very expensive looking  (and very small) plastic pieces,  I guess nothing lasts forever these days).

Good news, I dug out an old external card reader and that works.

Bad news, next the battery went flat, the second battery I tried was also flat. Good news, the third one is fully charged (and the others are now charging).

More good news, its my work laptop, so it looks like they will have to pick up the tab to fix it  :P

Bad news, after all that faffing about, its dark now, so no sunset time lapse from me tonight.

What do you want to test next?
« Last Edit: 29 / March / 2013, 17:00:57 by ahull »
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Offline srsa_4c

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Re: Shot Histogram Request
« Reply #178 on: 29 / March / 2013, 16:58:53 »
Quote from: ahull on 29 / March / 2013, 16:50:44
Bad news, RawTherapee cant make sense of the .DNG file (I'll investigate this later, maybe try  DNG 1.1).
EDIT: Nope, and .CRW looks like nonsense as well. Neither RawTherapee nor UFRAW can make any sense of them, they look like a noise with a narrow horizontal band of dark colour about 1/4 of the way down from the top.
This is fixed in the ixus30 port. Does it help if you set image size to L (I mean if it's currently set to a smaller size)?
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Offline ahull

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Re: Shot Histogram Request
« Reply #179 on: 29 / March / 2013, 17:03:28 »
Image size is set to Superfine and L (2272x1704)
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