Timelapse with variable shutter speed

Bruce Allen

3

Re: Timelapse with variable shutter speed

« Reply #50 on: 04 / May / 2008, 00:43:07 »

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Fbonomi, that's a sweet script you have there.

I am using it on an A650, with four modifications:

1. It was overexposing a bit so I increase Tv by 25 and decrease Sv by 25 just before I shoot
2. I take an additional highlight detail shot (Tv + additional 75, Sv minus additional 150) each pass
3. I decreased sleep times from 500 to 400 for the metering section, from 100 to 40 for all other sections. So far no ill effects!
4. I am using the get_tick_count function from the accurate intervalometer example to try to keep timings more constant as shutter speeds change. I THINK it's working, not too sure

In terms of settings, I'm running at slightly more conservative settings (Sv limit, etc) than your defaults, shooting wide aspect-ratio JPEGS and in post am combining with frame blending in After Effects, scaling down, running grain reduction and a stack of curves, sharpness, etc. So far, delighted with the results. This on the new allbest build, combined with dataghost's awesome 8gb SD card hack.

If I keep having good results, I'll let you know and post my variations for you to include if you wish (at the moment, haven't really contributed anything cool though...)

Anyway, THANK YOU, you rock.

Now, if only I could find some decent clouds in LA... your footage is beautiful BTW.

Bruce Allen
www.boacinema.com

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fbonomi

469
A570IS SD1100/Ixus80

Re: Timelapse with variable shutter speed

« Reply #51 on: 04 / May / 2008, 13:07:55 »

BA, glad you like it :-)

] 1. It was overexposing a bit so I increase Tv by 25 and decrease Sv by 25 just before I shoot
Very likely.

] 2. I take an additional highlight detail shot (Tv + additional 75, Sv minus additional 150) each pass
What do you mean?

] 3. I decreased sleep times from 500 to 400 for the metering section,
] from 100 to 40 for all other sections. So far no ill effects!

Yes... those were of cource just guessed values, the problems I was having is that some frames were way under-exposed (the set_tv96_direct was not working)

] 4. I am using the get_tick_count function from the accurate
] intervalometer example to try to keep timings more constant
] as shutter speeds change.

Yes, that was plain lazy of me...

] In terms of settings, I'm running at slightly more conservative settings (Sv limit, etc)
] than your defaults, shooting wide aspect-ratio JPEGS and in post am combining with
] frame blending in After Effects, scaling down, running grain reduction and a stack
] of curves, sharpness, etc. So far, delighted with the results.

Can you share a sample?

I have done almost NO post-processing, just the raw JPGs fed into my old Premiere 6,
plus a crude compression to MPG (that wastes a lot fo quality :-(
I guess there is a lot to improve there :-)

] I'll let you know and post my variations for you to include if you wish
Please yes, at least the get_tick_count change would definitely be a bonus

] your footage is beautiful BTW.
thanks!

PS your site gives a 403 error

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Bruce Allen

3

Re: Timelapse with variable shutter speed

« Reply #52 on: 05 / May / 2008, 04:18:04 »

Quote from: fbonomi on 04 / May / 2008, 13:07:55

2. I take an additional highlight detail shot (Tv + additional 75, Sv minus additional 150) each pass
What do you mean?

I take two shots per cycle:
http://www.bruceallen.tv/projects/2008/for_forum_posts/timelapse_normal.jpg
and
http://www.bruceallen.tv/projects/2008/for_forum_posts/timelapse_bracketed.jpg

Then combine them in post

my shooting code is now:

rem we can now shoot
sleep 40
set_sv96 (Y - 25)
set_tv96_direct (X + 25)
sleep 40
shoot
sleep 40
print "SHOOT",p,(X + 25), (Y - 25)
p=p+1
set_sv96 (Y - 150)
set_tv96_direct (X + 100)
sleep 40
shoot
print "SHOOT BRACKET",p, (X + 100), (Y - 150)
p=p+1

I THINK this gives me better latitude when I combine the two shots in post, HDR style.

Need to test to see which is best:

1. taking 1 long exposure shot at as low an ISO as possible
2. taking 2 shots with different bracketing
3. taking many shots as fast as possible and merging them in post

I am currently trying method #2, you are using method #1. Need to try method #3 too...

Quote from: fbonomi on 04 / May / 2008, 13:07:55

] 3. I decreased sleep times from 500 to 400 for the metering section,
] from 100 to 40 for all other sections. So far no ill effects!

Yes... those were of cource just guessed values, the problems I was having is that some frames were way under-exposed (the set_tv96_direct was not working)

I had that happen once. Going to test a bit more and try to figure out what is up.

BTW, regarding further speedups, I am trying putting it into MF mode beforehand, hopefully speeding up metering because no AF needed? I read somewhere on the CHDK forums you need to keep the display on (or connect the video out cable), or else the camera doesn't meter or focus properly? Not sure, need to test...

Quote from: fbonomi on 04 / May / 2008, 13:07:55

Can you share a sample?

http://www.bruceallen.tv/projects/2008/for_forum_posts/bruce_timelapse_test_3.mov

It looks great at 1920x1080 res BTW...

Quote from: fbonomi on 04 / May / 2008, 13:07:55

Please yes, at least the get_tick_count change would definitely be a bonus

at the moment, my code is simply this (please ignore the //, they are just to clarify):

// AT BEGINNING OF SCRIPT, JUST BEFORE MAIN LOOP
q = get_tick_count // get how many ticks have elapsed total since camera was switched on

// AFTER SHOOTING
l = 0 // keep track of how many ticks we wait
:sloop
r = get_tick_count // find out total ticks elapsed now (after shoot)
k = (r - q) / 3000 // k = total number of seconds it took to shoot (on my camera it seems to be
// 3000 ticks per second, not too sure

if k < a then // a = desired shot length
l = l + 100 // add 100 ticks to counter
sleep 100 // wait 100 ticks
goto "sloop" // test again
endif
print "WAITED",l
q = r // start counting ticks again for next cycle

// GO BACK TO MAIN LOOP NOW

Two things:

1. this is messy, should be a nice do while loop - it's been a few years since I last wrote much code

2. I need to take into account the fact that each line of code is supposed to take 10 ticks to execute

Quote from: fbonomi on 04 / May / 2008, 13:07:55

PS your site gives a 403 error

I know... haven't had time to update. Timelapse more important!

BTW, this is all for short film / music video / commercial / video art projects. Hopefully. Anyway, I was just watching the Wong Kar Wai film Chunkging Express tonight - and it had tons of well-used timelapse. I think it really helped the story. So this is hopefully not for nothing.

Next thing that I think would be cool would be to have a simple motorized rig. Even if you make something out of frikkin' lego - it would be cool if the camera slowly tracked in the foreground. Gonna try some crazy things involving that plus multiple cameras and lenses in the next few months and will need to send some beers in the general direction of you good CHDK guys if this ever gets used in a working project.

Also, if anyone has cool timelapse stuff that they'd let me use, let me know. Like I said, Los Angeles is the capital city of boring clouds and not exactly the most friendly place to set up cameras, etc.

Bruce Allen
www.boacinema.com (yes, I know, it's not working right now

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fbonomi

469
A570IS SD1100/Ixus80

Re: Timelapse with variable shutter speed

« Reply #53 on: 05 / May / 2008, 05:43:47 »

Quote

my shooting code is now:
...

you should check well the results.
What I have noticed is that sometimes the set_tv or set_sv would fail, and so some frames would either have the default values (the ones set up in manual mode) or "drag behind", i.e. frame X would keep the settings of frame X-1

In my case (a single sequence) this "dragging" is not terrible (as all frames have VERY similar values); in your case it woudl be worst (one frame of the light sequence being shot with dark parametes, for example...)

Quote

I THINK this gives me better latitude when I combine the two shots in post, HDR style.

In After effects?
Maybe it's time I upgrade :-(

Quote

Quote
Yes... those were of cource just guessed values, the problems I was having is that some frames were way under-exposed (the set_tv96_direct was not working)

I had that happen once. Going to test a bit more and try to figure out what is up.

As I said above, those frames keep the values set up via manual mode.
There is a bug is set_tv96_direct.

Even using the test program set_tv96_tst1.bas (in the sources it's in chdk\src\trunk\script), you often get the same problem: of the 4 shots, the first one often keeps the original values.

Quote

BTW, regarding further speedups, I am trying putting it into MF mode beforehand, hopefully speeding up metering because no AF needed?

Yes, I set it up in manual focus

Quote

I read somewhere on the CHDK forums you need to keep the display on (or connect the video out cable), or else the camera doesn't meter or focus properly? Not sure, need to test...

There is no need. I always turn the display off.
Afaik the only cases where you need the diplay on is when you are reading the viewport (for example, in motion detect scripts)

Quote

http://www.bruceallen.tv/projects/2008/for_forum_posts/bruce_timelapse_test_3.mov
It looks great at 1920x1080 res BTW...

Very smooth..
Mmmhh.... due to my laziness (and my poor video processing abilities) I shoot at 640*480.
What resolution do you shoot?
I undersand you have higher standards :-) but what resolution would you suggest to shoot in in order to get a NTSC-size video?

Quote

at the moment, my code is simply this (please ignore the //, they are just to clarify):

thanks

Quote

1. this is messy, should be a nice do while loop - it's been a few years since I last wrote much code

TIMTOWTDI

Quote

2. I need to take into account the fact that each line of code is supposed to take 10 ticks to execute

If you really want an exact timebase, we can make it another way and skip this problem altogether... (I will post something later)

Quote

Also, if anyone has cool timelapse stuff that they'd let me use, let me know.

I am afraid my ones have too low quality...
these
Time-Lapse clouds
are my best clouds, I can send you the JPGs if you want, but they are 640*480..

Quote

Like I said, Los Angeles is the capital city of boring clouds and not exactly the most friendly place to set up cameras, etc.

When shooting timelapses, I often leave the camera alone... My lady is always a bit worried about having it unguarded on top of a hill for a few hours.

I have painted my cheap tripod in camouflage-style (it was too shiny and reflexes were visible from miles away) but one day someone will find it anyway...

I am thinking about connecting a fake gizmo (a box with an antenna and a flashing led) to scare people so that they (MAYBE) won't take it away !

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avatorl

11

Re: Timelapse with variable shutter speed

« Reply #54 on: 05 / May / 2008, 09:05:40 »

Quote from: Bruce Allen on 05 / May / 2008, 04:18:04

I THINK this gives me better latitude when I combine the two shots in post, HDR style.

I want to try to create HDR timelapse video, and I think about using Photomatix in batch mode to combine every 3 shots (with bracketing) in HDR. Bruce Allen, how do you combine the shots?

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fbonomi

469
A570IS SD1100/Ixus80

First test of measuring exposure of shot just taken

« Reply #55 on: 06 / May / 2008, 04:28:14 »

A very crude test... but in line of principle it's running.

After every shot, the RAW data is read from memory and the exposure of next shot is adjusted accordingly.

The huge difference with the previous version of script are:
1) PRO: it can go up and down (sunset and sunrise)
2) PRO: it can avoid over-exposing if after sunset the sky is brighter than you expected (city lights reflected in clouds, for example)
3) CON: it requires a special build

to do some tests, I ran the capture and then moved the camera to lighter and darker areas of the sky, and the exposure was adapted accordingly.... somehow.

the (ugly) video is here: sensing shot exposure (nothing worth seeing, just to test)

Below is the Tv Graph, where you see exposure going up and down..

the question is: does anyone have some pointers to exposing algorithms? (I mean, algorithms that calculate exposure based on histogram of luminance)

I am afraid that I will end up doing very a specfic algorithm that won't be usable for other applications... a generic algorithm would probably save me a lot of work and give a better result...

test1.gif (3.27 kB, 569x392 - viewed 143 times.)

« Last Edit: 06 / May / 2008, 04:33:27 by fbonomi »

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Bruce Allen

3

Re: Timelapse with variable shutter speed

« Reply #56 on: 10 / May / 2008, 06:12:11 »

Thanks fbonomi.

To get standard-def TV-quality footage, anything over 720x540 should be fine. But I think life is short, so you might as well capture at a decent resolution so that you'll have something nice to watch in HD in a bit. Personally I'm shooting JPEGS at max res and quality but then I'm a bit crazy... It does mean you can do nice pans etc in post though.

It takes a long time to process - but then I just leave my computer to go and then go to work / sleep / etc...

RE: After Effects - it is not necessary but just useful with regards to frame blending and noise reduction.

If you found a recent version of Premiere, I think it has an option to blend frames when you do a speedup too.

Finally, I hope nobody ever steals your camera... one guy with a DSLR tells me he actually camps next to his camera most of the time!

BTW, if you ever think you've got a unique chance to do a good timelapse, I suggest you do it at full-res timelapse. If you get beautiful footage at at least 1920x1080 resolution, you have something which you can potentially sell. It's a long shot but if you feel like building up a portfolio, you shouldn't bother with less resolution than that because all of the competition is working at that resolution or more and using DSLRs.

Probably this suggestion will just waste your time and disk space but if you get something really unique and beautiful then be aware that high-end timelapse will sell for $300 per shot. Small change for the pros, but for us, that's probably the cost of our whole camea steup! Of course you'd need to build a portfolio, send stuff to stock footage companies like Getty images, Artbeats, etc.S o not really worth it - UNLESS you're going on holiday to some unique part of the world, or get a chance to get a shot at some famous historical location or something - then I say go for it!

Avatorl, I have not used Photomatix - I'm sure that'd work too. I basically just average everything together and then use my own setup of filters to do Photomatix-style effects.

Bruce Allen
www.boacinema.com

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fpalangie

15

Re: Timelapse with variable shutter speed

« Reply #57 on: 12 / May / 2008, 08:16:31 »

Hi Everyone,

I have been reading this thread with a lot of interest. I'd like to thank all of those who contributed to this work!

I have made a quick test of Fbonomi's script and it works great! ( Test - Rainy Day-Timelapse on Flickr - Photo Sharing! )

I am really waiting to see the dev of a script that would allow to do time lapse over a couple of days as i will be dedicating my S3 IS to do this job ( I am waiting to receive a power adapter).

I hope what Fbonomi mentions is what I am looking for...

Quote from: fbonomi on 06 / May / 2008, 04:28:14

The huge difference with the previous version of script are:
1) PRO: it can go up and down (sunset and sunrise)
2) PRO: it can avoid over-exposing if after sunset the sky is brighter than you expected (city lights reflected in clouds, for example)
3) CON: it requires a special build

« Last Edit: 12 / May / 2008, 17:59:56 by fpalangie »

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S3 IS
450D & 18-55mm, 100-400mm

Steveo

40

Re: Timelapse with variable shutter speed

« Reply #58 on: 12 / May / 2008, 09:22:51 »

Quote from: Bruce Allen on 10 / May / 2008, 06:12:11

It does mean you can do nice pans etc in post though.

What an obviously simple idea, why did I not think of that!! I always capture at full res, and then scale it down so you are getting the best possible image. And I have done a couple at full res and played them on my 42" plasma...yummy!!

But what a simple yet powerful idea of panning the full res image in post production... I was thinking how to get my camera to pan or move on the tripod over time; I think someone thought up something using lego etc. But if you're not bothered about true movement, a pan in Premiere etc would look cool... panning across a building as the sun sets etc!!

Just make sure you're not too close to anything in the foreground otherwise the illusion wouldn't work.

Cool idea and something for me to play with tonight!!

Steveo

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EOS 350D/XT User

fpalangie

15

Re: Timelapse with variable shutter speed

« Reply #59 on: 14 / May / 2008, 16:29:07 »

Hi all,

Well i have made another test during 5h, 920 photos, 1 photo every 20 seconds for a 38 second video in 1600x1200.

Ocean & Sky TimeLapse on Flickr - Photo Sharing!

During 5 hours there is a lot of luminosity change in the end due to this my pictures have more and more noise to them.

PS: link will guide you to veoh page where you can download the video in 1600x1200.

« Last Edit: 14 / May / 2008, 16:31:07 by fpalangie »

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S3 IS
450D & 18-55mm, 100-400mm