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Timelapse with variable shutter speed

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Offline lukg

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Re: Timelapse with variable shutter speed
« Reply #110 on: 23 / June / 2008, 11:29:40 »
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Thanks Francesco and mx3. i forgot to mention that i was going to use x264 codec...but I've just realised there's no vfw codec for x264 :(

EDIT: I've always had the solution under my nose. Quicktime Pro has "Open Image Sequence" and it compress in h264. Thanks guys!
« Last Edit: 23 / June / 2008, 11:42:53 by lukg »

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Offline lukg

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Re: Timelapse with variable shutter speed
« Reply #111 on: 23 / June / 2008, 12:04:02 »
Another question :D....one pic= one frame? (eg 25pics-->25fps) or do you use other settings?

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Offline fbonomi

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Re: Timelapse with variable shutter speed
« Reply #112 on: 23 / June / 2008, 12:12:51 »
it depends on fast / smooth  you want the movement

one pic=one frame -> fast and smooth movement (requires many pics)
one pic=several frame -> slow and "jumpy" movement (fewer pics are needed)

I prefer the first solution


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Offline lukg

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Re: Timelapse with variable shutter speed
« Reply #113 on: 23 / June / 2008, 12:28:52 »
Ok, thank you! I was interested in knowing what settings you used for your video! Thanks again!


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Offline topshot

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Re: Timelapse with variable shutter speed
« Reply #114 on: 15 / July / 2008, 12:56:51 »
Would it be possible to get a build for an A620? Or do I simply need the appropriate manual build from Jucifer and the script (v 10) from reply #79 here (or will v 12 from reply #100 also work)?

I got the impression this script requires RAW mode because of the histogram data, or can I still use JPEG?

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Offline Jucifer

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Re: Timelapse with variable shutter speed
« Reply #115 on: 15 / July / 2008, 14:55:20 »
If you use the collabuild, change the get_exp_info commands to get_histo_range.
e.g.
Code: [Select]
exp_get_info 100 800 hto
Code: [Select]
h=get_histo_range 100 800and put
Code: [Select]
shot_histo_enable 1before the ":loop" label.
I guess you should get better results with the newest script version.
The shot histogram data is from raw data (I think), but doesn't require raw saving to be enabled.

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Offline topshot

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Re: Timelapse with variable shutter speed
« Reply #116 on: 15 / July / 2008, 15:42:11 »
The shot histogram data is from raw data (I think), but doesn't require raw saving to be enabled.
Having zero experience with RAW, is not saving RAW something I need to set within the script or just the CHDK parameter under RAW settings? I guess I don't care if it saves both RAW and JPEG, but I'm only making my movies from JPEG. I don't have time to learn about and do all the post processing many here seem to do with the RAW files.

I just loaded CHDK 2 days ago so I'm not all that familiar yet. I'm going to the mountains this weekend so I want to experiment beforehand so I can capture sunrise/sunset. Thank you for the help, and for the devs who did all this great work.

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Offline topshot

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Re: Timelapse with variable shutter speed
« Reply #117 on: 16 / July / 2008, 09:09:46 »
For sunrises it seems to over-expose (at least for the sunrise I did this morning). The entire sky was nearly white, when the shutter went from 1/60 to 1/160 (which was still too long IMHO). The sun didn't finally break through a distant tree until 9 minutes later though there were some clouds reflecting the light as shown in the attached pic (this was the shot where shutter moved to 1/160). I also attached the pr_screen.txt file.

What parameter(s) do I need to change to make it get brighter slower?

Should metering mode be Pattern?

Thank you for the help.


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Offline Jucifer

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Re: Timelapse with variable shutter speed
« Reply #118 on: 16 / July / 2008, 11:49:06 »
saving RAW something I need to set within the script or just the CHDK parameter under RAW settings?

You don't need to set RAW saving. The shot histogram data is obtained from the RAW data before discarding or further processing (and saving) it.

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Offline topshot

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Re: First night-long time-lapse
« Reply #119 on: 18 / July / 2008, 15:48:46 »
This is the first (decent) result of a night-long time-lapse, including sunset and dawn.

2020 shots, from 19:30 to 06:45, with exposures ranging from 1/2000", 160 ISO to 20", 1500 ISO.

Here is the video: Night-long time-lapse 1

Better in MPEG1 format (abt 20MB): Night-long time-lapse 1

and below is the graph of the movie:

There are evident problems:
 - flickers in brightness around frames 650 and 1350 (we are at the very end of the sensors' reliability) and 1200 (moving averages method is not good for this sort of smoothing)
- around frame 700, the exposure is kept constant for a while. (In the movie, you get a short period of pitch black sky). In that moment the "over-exposure protection" was somehow triggered. I have to study exactly why.
Did you ever figure out why the overexposure correction kicked in? Mine has done the same thing on a sunset. It likely would have before had I let it run until it was darker.

My thoughts are your values for h being < 10 may be unreasonable (or maybe I didn't have enough sky - maybe 2/3 of frame). My h values started at 60 (sun still bright) and were nearly a straight line, still being 55 when the protection kicked in long after the sun set. Then it eventually dropped to near 0. I thought I had added in Bruce Allen's overexposure compensation (L-25 & M+25) but it turns out I forgot to copy that version over so maybe my h values would be much lower.

On comparing the shots at the end with values of h near 10, they seem OK exposure-wise for my conditions (city lights). I kind of prefer the dark bluer sky though of 30 minutes earlier (and 70 minutes after the sun had set) when the correction kept the shutter constant at 4" and h had finally dropped to 10 versus the dark gray sky at the end when the shutter was 13". I know I could change the Tv limit and likely will for those time-lapses I do at home. The ambient light should be far less where I'll be this week so results should be better with what I had used.

I also note that the only black pic I've had occurred when T=0 so I have now added a check to set it to 1 if that happens again. Maybe a fluke, but maybe a bug in set_tv96_direct?

Peace

 

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