|Timescapes - Digital Timelapse Discussion
|The ULTIMATE timelapse FAQ thread!
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|Author:||milapse [ Tue Feb 23, 2010 1:55 pm ]|
|Post subject:||The ULTIMATE timelapse FAQ thread!|
Why have you been sent here?
because this is the ultimate timelapse FAQ thread!! If you're new to the sport you might want to start by reading Timothy Allen's (BBC) great primer :LINK. Also, check out the wikipedia entry.
Here at the timescapes.org we get a ton of great questions about timelapse. This spot will serve as a one-stop repository for the questions that get asked the most. As new ones arise we'll continue to update this spot. If you're new to timelapse hopefully this will serve as a great start point for your exciting journey into the challenging and rewarding world of capturing timelapse photography. We're going to assume that you're looking for broadcast quality here as there's a HUGE number of budget solutions to timelapse (links?).
What is best way to capture timelapse; with stills or video 'sped up'?
There are advantages/disadvantages to both methods so being aware of the issues going in can save you a lot of headaches down the road. Today, the majority of timelapse enthusiasts probably use digital single lens reflex cameras (DSLR). Let's break it down:
-Ability to capture resolution far above final output. In other words if you're using a 10mp+ camera and your looking for 1080p you have lots of resolution to spare.
-Ability to capture RAW images (filenames ending in .CR2, .NEF etc.). The same holds true in timelapse as in traditional digital photography, capturing RAW data will give you the most flexibility in post but can come at storage and speed cost.
-Ability to adjust ALL settings. 99% of still cameras give you full creative control over exposure, aperture, ISO, white balance, and such. Many video cameras do not.
-Ability to see each shot displayed in the LCD - useful to monitor exposure and progress of motion.
-If you have a source resolution much higher than your final video output resolution, you can add pan and zoom effects within the frame in post production and not lose any video resolution. Your capture resolution should be as high as possible for this to look smooth and avoid artifacts.
-Speed, many times you can't get under 2-3 seconds per shot on a DSLR shooting RAW. You can shift to JPG for to get better speed (say even 2-3 FPS, which many cameras can do consistently with the shutter 'held down') but make sure you get your white balance correct and locked down. Also it's worth mentioning, when shooting RAW allow the camera's buffer to clear before the next shot! You may get missed frames if not.
-Time drain in post, shooting RAW can mean some serious time and computer resources in the post process. Again, JPG can speed things up but if you want ULTIMATE quality, remember to budget the time, memory and CPU.
-Easy! not much need to consider a lot. Make sure you've got settings locked to taste, power to last, press the REC button and chillax.
-Tape is in the past! most cams record direct to chip or drive now so it's easy to transfer directly into your timeline.
-FAST! Drop that file into the timeline, speed it up and voila timelapse.
-Not much flexibility, once it's recorded you can't do as much in post, for example unlike hi-res stills the pan-and-scan aka 'the Ken Burns effect is out of the question. So you pretty much have to get it right while shooting, color correct and live with it.
-Limited duration. Fill that memory and you're done. Some cams will simply stop recording after x amount of time.
-Power consumption. In general a running video capture will consume more power than stills.
How should I start shooting a timelapse with a DSLR?
- Get an intervalometer aka 'interval timer' (Hint: search ebay for "<your camera model> timer" for inexpensive clones. Also, www.linkdelight.com carries several models)
- Set the camera to manual mode(M), and set your desired exposure time, aperture, white balance (shooting RAW white balance not critical, if JPG setting WB is critical)
- Autofocus off.
- Use an exposure of longer than 1/100s to prevent shutter flicker.
- Use an aperture 'more open' than f/8 to minimize aperture flicker. (bonus: usually kills dust-specks as well)
[probably a video showing basic how-to on youtube]
My intervalometer only takes 99 shots!?
Many intervalometers are clones of brand name versions, like Canon's TC-80N3. It's a little unobvious, but they all take unlimited shots if you set the 'frame count' to 00. Follow these directions,
These particular intervalometers are often referred to as 'Timer remotes' because they offer functionality beyond simple intervalometry. Although these functions are usually of little interest to the time-lapse enthusiast, they can be useful in combinations (see final page of Canon Quick Guide) e.g. for bracketed time-lapses.
RAW or JPG?
It depends on the nature of your shot and what you think you will be using it for - serious or fun?
If you think you may want to sell your shot, edit it extensively (now or in the future as processing inevitably becomes cheaper/easier) or if you are just picky about the details, then shooting RAW is a good idea. If you think your shot will at most be rendered in 1080p for friends, family and the Internet and doesn't require extensive post processing, then you may as well shoot JPG (just make sure to set a good white balance).
It can be tempting for beginners to start out with RAW right away seeing that it is the choice of pros. However, the more effort (and HD space) each shot requires, the less shots you are likely to make. If RAW gets in your way, then you could be better off using JPG and shooting more often instead.
RAW and JPG?
You may want to shoot JPG in some cases and RAW in others depending on subject. RAW can help scenes with high contrast requiring shadow/highlight recovery or large areas with subtle gradations. On the other hand, if you need to capture high frame rate (drivelapses or people for example), cut post processing time or just want to capture a lot of footage, then JPG can be the better choice.
Wait... Shoot Full Manual?? what if light conditions change over time like day to night?
If you want the smoothest flicker free footage manual is the best, but you can go with auto settings... say aperture priority (a.k.a Av mode: aperture and white balance locked) and allow the camera to meter and determine the shutter speed (hint: cover your eyepiece! light can spill through it and affect the light meter!).
Great! Aperture priority mode (Av) and I'm all set?
Here's the rub... DSLRs have rough 'steps' between exposures (1/8-1/3 eV to be exact) and they can 'wander' slight over here and slight under there. This can be the most severe cause of FLICKER. Flicker remains the nemesis of most timelapsers who use DLSRs. Especially when there is a lot of brightness and darkness in a scene (aka dynamic range), the meter/camera is forced to make a judgement call; should I expose for highlights or shadows?...(rinse, repeat)...
Example of auto metering flicker on a DSLR...
What is this flicker you speak of? Why do you fear it so?
Flicker is generally caused by changing exposure between frames. It has many sources and can come severe like it's pounding gorilla brother 'strobe' or slight like its gentle kissin' cousin 'flutter'. Sometimes it's not the end of the world and can be remedied with post filters (hint: MSU deflicker & Graft ala virtualdub or GBdeflicker ala After Effects). Sometimes it's very difficult to expunge and you find your tears overflowing in your beers because that once in a lifetime sublime shot that you spent hours capturing now looks like disco fever. Not so good!
De-flickering software example...
Aperture flicker - this occurs when the lens' diaphragm is contracted for each shot. This occurs with modern automatic lenses. In contrast, manual lenses may allow you to set the aperture once and for all. When the aperture diaphragm is actuated with each shot, small mechanical inconsistencies result in small exposure errors, appearing as flicker in the final time-lapse. It is at its worst when the lens diaphragm has to stop down to very small apertures with each shot (e.g. f/16, f/22 ...). To understand how this shot-to-shot error can arise consider this slow-motion video.. Note that when a lens is used 'wide open' (i.e. at its widest aperture), the lens diaphragm generally isn't active at all, and so no aperture flicker will result. However, the most reliable way of preventing aperture flicker is to lock the diaphragm: use the Depth of Field preview button (the button on your camera by the lens mount) to move the diaphragm into position, and at the same time disengaging the lens, rotating it slightly. The lens will now be stopped down to the desired f-stop and be electrically disengaged from the camera body. Although the camera will not think there's a lens attached you may still be able to take photographs - this doesn't work with all cameras (list of cameras). On Canons you may get an err 99 message - this usually means the electrical contacts are still somewhat engaged, and you may need to twist the lens a little further. One can also just put tape over the lens contacts, although this can be slightly less convenient if changes need to be made to the aperture later on.
Shutter flicker - Small mechanical errors also occur in the shutter mechanism. Again, it is most severe when the mechanism is pushed to its limits (i.e. high shutter speeds). Although there's little that can be done about this flicker, you should get essentially flicker free results if you shoot at shutter speeds slower than 1/100s. This is usually not a problem as one often wants to 'drag the shutter' anyway (see below).
Intervals (time between the start of each shot) where do I start?
-The easiest 'one size fits all' way around intervals is to get them as 'tight' as possible. So if your exposure is under 1 second simply take a shot every second BUT with many cameras (as mentioned in the 'stills or video' section) can't purge the buffer quick enough (especially shooting RAW) so you'll have to make sure your buffer clears before taking the next shot. On the other hand many bodies can do like 3 frames per second JPG continuous if you simply lock down the exposure button (most interval timers have this function).
-On the other hand you're sucking up memory quickly by going as tight as possible and it can be overkill, so one approach is to shoot some sample frames and scroll review them on camera. This will give you quick feedback on the resulting footage so you can adjust... maybe longer intervals will be fine, maybe shorter will give you what you're looking for...
-Some ballpark interval starting points to try out...
Fast moving clouds: 1 second
Slow moving clouds: 10 seconds
Sun moving across a clear sky: (wide) 20-30 seconds
Stars moving across the sky: (wide) between 20-60 seconds
Sunsets close up: 1-2 seconds
Crowds of people: 1-2 seconds
Plants growing eg cucumber vines: 2 minutes
Shadows moving across the ground: 10-20 seconds
Note these times can change drastically depending on the local conditions, and the aesthetic look you are trying to achieve, so the best answer is to get out there and practice for yourself to see what works for you. As a general rule of thumb, any tighter or telephoto shots need much faster intervals.
Drag your shutter? What are you talking about?
When shooting a timelapse the intervals between photographs are often rather long (seconds or longer) giving the photographer considerable latitude in choosing the exposure times of the individual shots. Obviously, very short exposures yield a sharp image free of possible motion blur, whereas a longer exposure gives more blur. Additionally, the longer exposure captures more of the action that is occurring between shots (in a sense adding it all up in a single frame). Since these images will be played back in sequence (in the form of a movie) it is often desirable to aim for frame-to-frame continuity of the action being captured. This generally yields smoother timelapse footage. Increasing the exposure time to fill the shot-to-shot interval is known as 'dragging the shutter' and is related to shutter angle in cinematography (wikipedia)
How do I set my focus wide open for stars?
Every lens is unique on a particular camera body. By using magnified 'live view' functions or by test shooting a small rage around the infinity mark (the sideways 8 ) you can find the sweet spot. Sometimes the slightest twist can produce very different coma effects as well.
Usually you can get a good lock with autofocus if there is a bright object more than about 100ft / 30m away. A street lamp works well, or if you are in a dark area with not natural light, you can leave a light on the ground a good distance away to get your initial focus lock before switching to manual focus.
Sometimes a high-power laser can come in handy in remote areas to light up a distant object. Just remember to be very cautious where you point it, they can cause permanent damage to both camera sensors and other people.
How do I compose a movie from the stills?
From free to pricey:
- Photolapse 3 http://home.hccnet.nl/s.vd.palen/
- VirtualDub http://www.virtualdub.org/
- QuickTime Pro (free with Mac OS 10.6) http://www.apple.com/quicktime/pro/
- Adobe Premiere Elements http://www.adobe.com/eeurope/products/premiereel/
- Lightroom http://www.adobe.com/products/photoshoplightroom/ PRESETS!:http://lightroom-blog.com/presetsmain#timelpase
- Final Cut Pro http://www.apple.com/finalcutstudio/finalcutpro/
- Adobe After Effects http://www.adobe.com/products/aftereffects/
For all these programs it's important that the images are numbered in chronological order: e.g. img_00001.jpg, img_00002.jpg etc. To rename your files on PC, there is for example:renamemaster or bulk rename utility. On a Mac you can use Automator (example workflow) to not only rename files in numerical order but also extract them from separate folders on your camera's CF card. Some camera models allow you to reset the file numbering, i.e. restarting it at img_0001.jpg, thus helping you avoid the need for any subsequent file renaming.
Timelapse "Holy Grail"?
Sunset, Sunrise, Day to Night Transitions
Round here we call the flawless 'flicker-free' transition from daylight to stars the Holy Grail. More generally, it is some as-yet-unknown method/tool for utilizing the camera's broad range of exposure capabilities (covering well over 20 stops) without introducing undesirable artifacts. You may get lucky and stumble upon the Grail by setting your camera to full auto ('green mode') and shooting away but, let's just say if you press your luck you might get the most horrendous flicker you've ever seen. There are a few theories on how to dependably attain the Grail, covering both 'in-camera' and 'post-production' solutions:
We've heard that Fricke used this as the film 'grand-daddy way' to go from day to night. Essentially stopping the timelapse capture, adjusting the exposure and restarting. Then in post cross-fading the exposures to get the illusion of day to night.
If you have two cameras with identical set-ups side by side (and nothing too close in the foreground) you can manually change the exposure on one camera at a time, keeping the EV steps about one stop apart. As camera "A" falls to about -1, and camera "B" is on 0, reset camera "A" to be +1. As the light continues to fade, and camera "B" reaches -1 with camera "A" on 0, reset camera "B" to be +1, and so on. Then in post, fade back and forth from one camera to the other.
Unlike the camera's built-in shutter speeds, the Bulb mode (B) allows the photographer to expose for an arbitrary duration. Despite being designed for ultra-long shots, bulb exposures can be as short as 1/30s on high-end dSLRs. By smoothly varying the duration of the Bulb exposure, it is possible to seamlessly follow the changing light conditions. The ramping can be controlled automatically by an external light meter (link to thread), or manually (link to thread) - both requiring microcontroller gadgetry. The exposure latitude offered by this method is only limited by the longest bulb exposure you can tolerate. For example, from 1/30 to 3s exposures represents over 6 stops. It is also possible to use the photographic concept of reciprocity (wikipedia) with ISO (and/or aperture and neutral-density filters) to extend its usefulness.
Manual lenses offer the photographer the possibility of manually rotating the aperture ring. If done slowly during the course of a time-lapse one can achieve a smooth change in exposure, spanning the f-stop range of the lens. This is typically about 6 stops - comparable to the practical range of bulb exposure times. An aperture drive is usually a highly geared or stepper motor that rotates the aperture ring via belt or toothed gear. To make the aperture ring smooth, the ball-bearing that holds the ring at discrete positions needs to be removed. On some lenses this is easy to do, on other lenses (e.g. Asahi Takumars) it requires considerable dismantling.
By bracketing out shots for the entire exposure range, separating them into folders and renumbering, then 'stacking' the exposures in a timeline. One can fade from one desired exposure to the next! Sweet.
EXIF extraction/metadata manipulation
There have been some ideas about shooting time-lapse sequences in Av, Tv, P or M mode and allowing the exposure to change freely (or manually). In the most formal version of this post-process intensive method, we adjust/smooth over the exposure steps according to the exif data contained in the individual frames. In effect, we reconstruct the history of light changes that actually occurred during the time-lapse session. This is subtly different form applying deflickering algorithms based on histograms, because the exif data unambiguously tells you the true exposure, whereas histograms provide a less objective measure. It is desirable to then write the requisite exposure corrections as metadata for use in a RAW workflow. One outstanding issue regarding this post-processing method is how to deal with saturated pixels.
There is quite a good tutorial by Preston Kanak available here... http://www.prestonkanak.com/2013/06/12/ ... me-lapses/
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