Zoom intervalometer - page 2 - Script Writing - CHDK Forum
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Zoom intervalometer

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Offline waterwingz

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Re: Zoom intervalometer
« Reply #10 on: 13 / July / 2015, 12:49:51 »
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Quote from: ojobojo on 13 / July / 2015, 10:59:51
Now, if CHDK has the possibility to actually keep the iris open all the time and only use the electronic shutter to record the frame then I reckon that would completely eliminate variation due to slight differences in the iris opening from frame to frame
Forcing the exposure calculation to use and set the maximum aperture setting would be easy.   I suppose one other source of flicker is the discreet jumps in f-stop and ISO sensitivity causing slight differences in exposure as the lighting changed.

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A note before the report: the SX40 I am using has a M mode where I choose the speed and aperture and also a manual focus setting which I use in the testing. I think this overrides the script's settings but it still takes exposure and focus measurements when it moves between zoom levels.
Unless I am mistaken, CHDK will overrides your manual settings.

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Issues I found when testing now the latest version 3: the first frame at a zoom level is still under-exposed compared to the rest at that same zoom level
Strange. The first shot is simply a shoot( ) command, which does the exact same thing as pressing the shutter button.  If you have the camera in AUTO or P mode that should give the correct exposure.  If you are using M mode or an Ev offset value then it might be different.

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- when I put the timer at 2 seconds between frames when it moves to the next zoom level and takes measurements the delay becomes 4 or 5 seconds then within the same zoom level it is 2 seconds
The script inserts some additional delays when it sets zoom position and refocuses.  That's because we can't tell in the script when those actions have completed but if you don't wait long enough strange things can happen.  The loop timing compensatea for this until it gets too short to do the delays and take a shot (typically 2 secs). You can try editing the delays. YMMV.
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Offline ojobojo

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Re: Zoom intervalometer
« Reply #11 on: 13 / July / 2015, 18:07:00 »
Thanks waterwingz, I think things are becoming clearer now. In that case is it possible to modify the script so it does the following:

- take the manual speed and aperture values and focus information from the camera rather than have CHDK calculate it every time and override it (essentially lock exposure and focus prior to shooting). This will also potentially decrease the delay between zoom steps as there will be no refocus.

- have an ND setting prior to shooting to adjust for bright scenes (if possible)

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Offline waterwingz

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Re: Zoom intervalometer
« Reply #12 on: 13 / July / 2015, 18:54:19 »
Quote from: ojobojo on 13 / July / 2015, 18:07:00
take the manual speed and aperture values and focus information from the camera rather than have CHDK calculate it every time and override it (essentially lock exposure and focus prior to shooting).
If you have the camera in M mode, then when the script starts the first shot will use those setting.  As will all subsequent shots.   (I think I confused things with my previous comment).    The only thing I can think of that would cause the first shot to differ from the rest is if you have an Ev offset value set in the Canon menu?

It would be easy to have the script not set exposure at all.  If the camera is in M mode it should just use those settings.  You should be able to force the ND filter using the Canon menu that way too.


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Offline ojobojo

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Re: Zoom intervalometer
« Reply #13 on: 14 / July / 2015, 10:08:18 »
Thanks Waterwingz, I ventured in editing (simplifying) the script and pretty much nailed the functionality by removing the ND bits and setting MF outside of the main loop and it works by getting the manual values i dial in the camera.

However now i did some more testing comparing the two scripts and found a major issue which i am not sure where to address as it appears in both scripts.

Massive barrel distortion as if they are RAW images without correction: you can see in the attached photos zoomed in and out how bad it is.

So my question is why does it produce it? The in camera software corrects it automatically when shooting outside of CHDK.

Is there a way to use the in-camera correction in CHDK? I haven't had the issue running other intervalometer scripts (without the zoom functionality)

Thanks
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Offline ojobojo

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Re: Zoom intervalometer
« Reply #14 on: 14 / July / 2015, 10:11:24 »
Oh and here is the modified version of the script.
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Offline waterwingz

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Re: Zoom intervalometer
« Reply #15 on: 14 / July / 2015, 11:38:15 »

Quote from: ojobojo on 14 / July / 2015, 10:08:18
Massive barrel distortion as if they are RAW images without correction: you can see in the attached photos zoomed in and out how bad it is.

So my question is why does it produce it? The in camera software corrects it automatically when shooting outside of CHDK.

Is there a way to use the in-camera correction in CHDK? I haven't had the issue running other intervalometer scripts (without the zoom functionality)
The answer is simple but you are probably not going to like it.  As you may recall, I suggested that a refocus would be necessary after each zoom movement? Looks like I was right.  The zoom command simply moves the lens - a refocus tells the Canon firmware to reset the lens correction.  The cheap little lenses on these cameras are not the same as the old 35mm film lenses. They need varying amounts of correction at pretty much every setting.
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Offline waterwingz

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Re: Zoom intervalometer
« Reply #16 on: 15 / July / 2015, 23:14:28 »
Updated version of script attached.   Allows user to select :
  • exposure resets with each shot,  or after each zoom set,  or only on first shot
  • focus locks after each zoom step,  or only on first shot
  • Ev offset adjustment
  • ND filter auto,  always in,  or always out

If you put your camera in M mode (or Tv or Av priority) and set the script to exposure mode = auto then pictures will be taken with your Canon manual setting.

Similarly,  if you set MF in the Canon menus and select Focus = auto mode then the pictures will be taken with the Canon MF focus setting.

Edit : attached script removed. Updated version posted later in this thread.
« Last Edit: 07 / April / 2018, 17:28:49 by waterwingz »
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Offline ojobojo

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Re: Zoom intervalometer
« Reply #17 on: 16 / July / 2015, 09:53:47 »
Thanks Waterwingz, apologies for the delay in reply but am quite busy with other menial stuff ;] I actually found a way to make the barrel distortion disappear - it's just a matter of pre-focus and letting the camera adjust before starting the shoot (no change in the script). It's not a 100% sure method but it works.

I have uploaded a video here with the tests i did the other day. You can see in the first part the barrel distortion which is then gone in the following clips.

The zoom is jittery but more testing and post-production motion smoothing filters will probably be necessary to get that right.  I also noted something that i supposed - the optical rate of zoom at the wide end seems faster than at the telephoto.

I will test the latest version you posted here and come back with more feedback.

I was thinking it would be nice to put a zoom end level so it doesn't go to the highest or lowest value necessarily but a user-specified one. And also keep shooting at that level until interrupted.

Thanks again
« Last Edit: 16 / July / 2015, 09:55:52 by ojobojo »
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Offline waterwingz

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Re: Zoom intervalometer
« Reply #18 on: 16 / July / 2015, 15:17:28 »
Quote from: ojobojo on 16 / July / 2015, 09:53:47
I also noted something that i supposed - the optical rate of zoom at the wide end seems faster than at the telephoto.
I could add the ability for the script to load a small calibration file - an easy to edit text file that specifies how many shots to take at each zoom setting.   You could specify the number of shots at every zoom step but if you only provided a few discrete breakpoints, the script could interpolate linearly between them.

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I was thinking it would be nice to put a zoom end level so it doesn't go to the highest or lowest value necessarily but a user-specified one. And also keep shooting at that level until interrupted.
I like the idea.  Updated script attached.

Edit : attached script removed. Updated version posted later in this thread.
« Last Edit: 07 / April / 2018, 17:29:11 by waterwingz »
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Offline c_joerg

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Re: Zoom intervalometer
« Reply #19 on: 20 / August / 2015, 15:46:20 »
I run the izoomer on G1x and SX230. On G1x it works fine but on SX230 it crashes (cam goes off) after first change of zoom…
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