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#1 Renny McCauley

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Posted 05 January 2010 - 04:18 PM

I'm doing a full day time lapse of a city scape starting just before sunrise and ending just after sunset. We're shooting this on a Arri SR2 with an intervalometer. The interval will be 20-30 seconds per frame. I'm a little unsure on setting exposure. My instinct was to meter every shot and adjust the exposure accordingly, but maybe this will look jittery? What would you folks do?

Thanks,
Renny
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#2 Alessandro Machi

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Posted 05 January 2010 - 04:44 PM

The interval will be 20-30 seconds per frame.


meaning the interval between exposures rather than a 20-30 second exposure? Are you using a certain shutter duration per each exposure?


I'm a little unsure on setting exposure. My instinct was to meter every shot...


as in every 20 to 30 second interval you would remeter?

and adjust the exposure accordingly, but maybe this will look jittery? What would you folks do?

Thanks,
Renny


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#3 Renny McCauley

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Posted 05 January 2010 - 05:22 PM

To clarify, there will be an interval of 20-30 seconds between each exposure. I believe we'll use the default 180º shutter. It's a shot of San Francisco from on top of a hill.

Renny
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#4 Tom Lowe

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Posted 06 January 2010 - 01:02 AM

If you need sunrise-to-day and then day-to-sunset, you'll have to adjust the shutter speed, probably.

Probably try to change it at the smallest increments possible, and only in one direction. If exposure goes up and down (instead of only in one direction), then you will get "flicker" from frame to frame. Then, obviously, as sunset comes, you will change the exposure duration back in the other direction, manually, in small increments. The good news is, you will probably only need to adjust exposures during sunrise and sunset, because it will be fine to leave most of the daytime frames at one exposure all day, assuming the weather is decent.

The timescapes forum in my signature is dedicated to nothing but timelapse, so if you need any help, give it a try.

Edited by Tom Lowe, 06 January 2010 - 01:03 AM.

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#5 Alessandro Machi

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Posted 06 January 2010 - 03:25 AM

I would also make sure you avoid lens flare or anything close to lens flare as that will probably be more ruinous than changing brightness levels. Of course it depends what kind of lens flare as well. some lens flares look cool, and others not so cool.
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#6 David Rakoczy

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Posted 06 January 2010 - 08:35 AM

...and if the sun is beating into the lens you should probably consider a Capping Shutter.

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#7 Renny McCauley

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Posted 06 January 2010 - 01:04 PM

...and if the sun is beating into the lens you should probably consider a Capping Shutter.

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Thanks for all the help guys. The sun will actually be behind us the entire time as we are shooting north. This helps things a bit.

I'm now considering moving over to 250D film so that we get the building lights properly. But then I might be entering ND land at full sun. Adding filters to the mix seems super tricky.

Tom, you say to adjust the shutter speeds. It seems like this will have an undesirable effect in that the longer exposures will be streaky while the faster shutters will be stuttery. Right? Beautiful timelapse work on your site, by the way.

Renny
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#8 Tom Lowe

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Posted 06 January 2010 - 01:13 PM

Thanks for all the help guys. The sun will actually be behind us the entire time as we are shooting north. This helps things a bit.

I'm now considering moving over to 250D film so that we get the building lights properly. But then I might be entering ND land at full sun. Adding filters to the mix seems super tricky.

Tom, you say to adjust the shutter speeds. It seems like this will have an undesirable effect in that the longer exposures will be streaky while the faster shutters will be stuttery. Right? Beautiful timelapse work on your site, by the way.

Renny


Yes you will have the effect of things speeding up (clouds, boats, etc) and slowing down as shutter speeds decrease or increase, but there are not a lot of other options. You can ride the iris, but then, your focus and DOF can change. Some old-school 35mm film guys did ride the iris, I know. It needs to be adjusted in tiny increments, smoothly, of course. I think adjusting shutter speed is usually the best route to go, as far as I have seen. I would avoid the filter route, because as you said, it introduces a lot of difficulties.

Any reason you are doing this on film rather than a digital SLR? I suppose it's to match the rest of the production?
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#9 Kristian Schumacher

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Posted 06 January 2010 - 01:34 PM

If you need sunrise-to-day and then day-to-sunset, you'll have to adjust the shutter speed, probably.

Probably try to change it at the smallest increments possible, and only in one direction. If exposure goes up and down (instead of only in one direction), then you will get "flicker" from frame to frame. Then, obviously, as sunset comes, you will change the exposure duration back in the other direction, manually, in small increments. The good news is, you will probably only need to adjust exposures during sunrise and sunset, because it will be fine to leave most of the daytime frames at one exposure all day, assuming the weather is decent.

The timescapes forum in my signature is dedicated to nothing but timelapse, so if you need any help, give it a try.



Hi Tom,

I have seen your beautiful timelapses - absolutely stunning.. I am just curious why you would choose to change shutter speed during the shoot. Wouldn´t a set exposure give a nice fade in at sunrise and fade out at sunset? If I change exposure by say 1/3 stop from one frame to the next ( i think that is the minimum on my camera), will it look fine and not "jumpy" ?
Just trying to pick your brain so one day my timelapses will be as nice as yours ;-)

Thanks,

Kristian

Edited by Kristian Schumacher, 06 January 2010 - 01:37 PM.

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#10 Tom Lowe

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Posted 06 January 2010 - 01:52 PM

Hi Tom,

I have seen your beautiful timelapses - absolutely stunning.. I am just curious why you would choose to change shutter speed during the shoot. Wouldn´t a set exposure give a nice fade in at sunrise and fade out at sunset? If I change exposure by say 1/3 stop from one frame to the next ( i think that is the minimum on my camera), will it look fine and not "jumpy" ?
Just trying to pick your brain so one day my timelapses will be as nice as yours ;-)

Thanks,

Kristian


Yes, that's the way I do it. But Renny said he was "starting just before sunrise and ending just after sunset." So that is a lot of stops of adjustment needed.

When I do sunsets, for example, I generally start the sequence 2 stops over and end it 2 or more stops under, for that nice fade effect you mentioned. Sometimes I let it fade all the way to black.

For one "day-to-night" sunset shot I did of the LA skyline in June, I went to the location the night before and discovered what the lowest night-time exposure was I could get away with. Say, (just for example) 1 second at ISO 100 f/2.8. Then, I waited till after sunset and watched my exposure meter until the scene was about 3 stops over. Then I started the timelapse. This way, you can go from a bright "daytime" shot (even though it was well after sunset) to a well-exposed night. This shot became the opening sequence of an international Audi commercial, so it seems to have worked.
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#11 Alessandro Machi

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Posted 06 January 2010 - 04:07 PM

Any reason you are doing this on film rather than a digital SLR? I suppose it's to match the rest of the production?


At this point, film is still digital format agnostic, meaning it can be transferred to any existing digital format or format not yet invented.
Film should also handle the contrast latitude better but it is most likely more work to get the same shot. However, once the shot has started it is standing around no matter what format it is.

How do you define your digital SLR recordings from a digital video point of view?
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#12 Tom Lowe

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Posted 06 January 2010 - 09:32 PM

Well I shoot everything in 14-bit Canon RAW stills and process the sequences with Adobe Camera RAW in After Effects. You can transcode to any format, directly off the RAW files, from within AE.
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#13 Chris Burke

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Posted 06 January 2010 - 11:40 PM

Thanks for all the help guys. The sun will actually be behind us the entire time as we are shooting north. This helps things a bit.

I'm now considering moving over to 250D film so that we get the building lights properly. But then I might be entering ND land at full sun. Adding filters to the mix seems super tricky.

Tom, you say to adjust the shutter speeds. It seems like this will have an undesirable effect in that the longer exposures will be streaky while the faster shutters will be stuttery. Right? Beautiful timelapse work on your site, by the way.

Renny



7207 handles overexposure very well. I would recommend that as your stock choice. no nd
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#14 Alessandro Machi

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Posted 07 January 2010 - 12:15 AM

Well I shoot everything in 14-bit Canon RAW stills and process the sequences with Adobe Camera RAW in After Effects. You can transcode to any format, directly off the RAW files, from within AE.


Have you ever outputted to tape?
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#15 Renny McCauley

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Posted 07 January 2010 - 12:34 AM

7207 handles overexposure very well. I would recommend that as your stock choice. no nd

Just an update. We got the intervalometer today. The FASTEST shutter speed the intervalometer can do is 1/8 second. So that changes things a bit. We don't have any ND filters so we are going with the 50D stock.

What I've decided to do is start about an hour before the sun actually rises and start with a 1 second shutter and full open aperture. Over the course of the hour I will speed up the shutter to 1/8. Then over the next hour I will begin lowering the iris from wide open at 1.2 all the way down to f22. Ride out the day at f22, then do the operation in reverse.

Hope it works. I feel like it will.

Thanks for the help!
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#16 Tom Lowe

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Posted 07 January 2010 - 04:15 AM

Have you ever outputted to tape?


Lol what is "tape"? :lol:
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#17 Alessandro Machi

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Posted 07 January 2010 - 05:48 AM

Lol what is "tape"? :lol:


Tape is how you authenticate that your edited piece actually runs in real time without any dropped frames or other unforseen issue that could otherwise be masked when viewed in the native format.
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#18 Alessandro Machi

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Posted 08 January 2010 - 06:04 PM

Just an update. We got the intervalometer today. The FASTEST shutter speed the intervalometer can do is 1/8 second. So that changes things a bit. We don't have any ND filters so we are going with the 50D stock.

What I've decided to do is start about an hour before the sun actually rises and start with a 1 second shutter and full open aperture. Over the course of the hour I will speed up the shutter to 1/8. Then over the next hour I will begin lowering the iris from wide open at 1.2 all the way down to f22. Ride out the day at f22, then do the operation in reverse.

Hope it works. I feel like it will.

Thanks for the help!

Full open aperture involving lights and time-exposure can sometimes get ugly. You may want to consider starting at 2.0 or 2.8, or even a 2.8/4 split and letting the exposure ride in, as was explained in a earlier post by Tom. You'll get a crisper, deeper black to start with, and assuming you will have traffic in the shot, the traffic lights will still read, but they will probably look sharper if you avoid being wide open.

However, that 50 ASA is a bit low so I could see why you would want to be wide open, but I think you can get away with not being wide open as well, especially if you are starting with a one second exposure, you can probably get away with an f 4.0. My experience is entirely in Super-8, but I probably have shot as many time-exposure hours in Super-8 as most people have shot in the higher formats simply because it was so inexpensive to shoot.

You can see some samples at http://www.8mm-stockfootage.com/

The one time I had access to a programmable time-lapse bolex set up, the slowest it would do was something like 1/2 second or maybe 1 second, but it could do a faster shutter as well. This is what always drove me nuts about the 16mm and 35mm time-lapse set ups. Either they would only go down to 1/8th of a second, or if they could be left open longer, you could not see through the viewfinder when the shutter was open.
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#19 Renny McCauley

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Posted 17 January 2010 - 11:52 AM

I wanted to chime back in about the time lapse after the fact because you all have been VERY helpful. The shoot was not a complete success but it was also not a complete failure.

The major problem was that the intervalometer that we rented (Norris) had a minimum shutter length of 1/8. I had assumed that I would be able to at least shoot at 1/48. I shot without an ND filter. I did not rent one because I didn't think I would need it. By full sun I was a good 3-4 stops overexposed. It was also a very foggy day and the frame was a complete whiteout at times (we were shooting from up high on a hill overlooking San Francisco).

As for strategy, I decided to ride the exposure to get both day and night exposures. We used 250D. I only had a cheap Sekonic meter and not until 6:45 or so was I getting a reading at all, so I had to guess up until that point. I started with a 1 second exposure at about 6:00am and as the sky became lighter I cut off 1/16 of a second at a time. By the time the sun came up, I had a 1/8 shutter and 1.25 f-stop which was accurate on my light meter. Then I closed up the f-stop in about 1/10 stop intervals (just manually) trying to keep up with my light meter readings. By the time I reached full closure at 16 f-stop, I let it stay until the sunset began, then I did the process in reverse.

I feel like the strategy was good, though I won't know for sure until the telecine later this month. I'm nervous about the overexposure, but I think it will turn out okay.

Again, thanks all for the suggestions and help. I can't wait to try again and refine my strategy. I think the time-lapse can be a pretty great experience.

Renny
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