Tutorial Guide - Time Lapse Photography with a Neutral Density Filter

The process of creating a moving of an image from a series of photos (time lapse photography) can have the undesirable effect of jittering when objects move quickly in the scene. The jitter can be smoothed and blurred using a neutral density filter. The video below shows an example of this jittery effect followed by footage of the same scene using a neutral density filter.

A neutral density filter is designed to reduce the amount of light entering the camera lens evenly over the colour spectrum (hence a neutral filter). The reduced light allows you to significantly increase the exposure time and capture objects that are moving quickly through the scene resulting in a motion blur rather than an instant snap shot.

Neutral density filters are ideal for daytime or well lit time lapse scenes containing rapidly moving elements such as

• Crowds of people, such as a conference or market place
• Waves on the water
• Trees swaying in the breeze
• Wind mills or propellers
• Traffic

The one drawback of using a neutral density filter is the low light operating conditions of a digital camera, you will need to consider the following.

• if the exposure time is greater than 1 second, your camera may need to take a dark exposure to compensate for CCD imperfections. For example if you set an exposure time of 10 seconds, the camera may take 20 seconds to complete the exposure (plus overhead for recording the image to the memory card)
• the increased exposure time will significantly reduce the battery life of the camera, this is worth considering particularly since a time lapse film may potentially consist of thousands of photos.
• images may become grainy if the exposure time is very long.

With these limitation in mind you will need to choose an appropriate exposure time, in my experience a suitable exposure time would be 1/4 to just under 1/2 of the interval time (time between photos). In the video above the exposure time was 2 seconds, with an interval time of 5 seconds.

Type of Neutral Density Filters

Neutral density filters come in a range of strengths or attenuation factors, typically these filters are labeled as ND2 or ND1000, where the number after the ND is the attenuation factor.

You can determine how much light is passed through the filter by dividing 1 by the attenuation factor, for example an ND2 filter has an attenuation factor of 2, and the amount of like which passes through the filter is 1/2 which is 50%. An ND8 filter lets only an eighth (1/8) of the light pass through or 12.5%

When choosing a neutral density filter it is worth while visiting your local camera store to seek advice on which filters best suit your digital camera. Some cameras require a special hood adapter to allow you to attach a filter. Filter also come in a range of sizes and it will be nessesary to use a filter of the correct size, or to purchase stepping rings that will allow you to use a filter of a different size on your particular camera.

Tutorial Guide - How to make your own Time Lapse movie

With the proliferation of affordable Digital still cameras it has never been easier to cut together your own time lapse film. In this tutorial we discuss using a digital still camera (either a compact or SLR) together with a video encoding software package such as QuickTime Pro 7 or Google Picasa. 

This tutorial covers:

 The basic concept of Time Lapse photography;

1. Camera Equipment required to take Time Lapse photography;
2. Choosing a suitable scene for a Time Lapse film;
3. Camera settings that may improve the quality of the time laspe footage;
4. Filming a time lapse movie with a digital still camera;
5. What to remember when tranfering the photos to your computer;
6. Converting the photos into a video;

1. The basic concept of Time Lapse Photography

Time lapse photography is very similar to stop motion animation. A typical film or animation consists of frames (or in our case photos) which are displayed at rapidly one after another animate the scene. In a standard movie, frames are filmed at 24 frames per second and are played back at the same speed (24 frames per second).

The power of thime lase photography is that instead of filming something at the same speed as you would play it back, you take photos of a scene at a much slower rate than you intend to play them back. For example, you can take a photo of clouds once every 5 seconds for two hours, and then play them back at a rate of 30 photos per second, resulting in a film that is showing the clouds moving 150 times faster.

 2. Camera Equipment Required to take Time Lapse photography

Digital Camera and Interval Timer

While any digital camera could be used to take time lapse photos, it is extremely useful if the camera you have or are about to buy has the following features:

• An interval timer (or intervalometer)
• Manual settings for shutter speed, focus, white balance and apeture
• Access to the manual settings while using the interval timer
• Affordable spare batteries and the option to purchase an AC adaptor
• Support for large memory cards (time lapse involves taking lots of photos).

Interval timers allow for a regular automatics timing between photos, they can either be part of the camera itself or in the case of some Digital SLR camera, an external accessory that trigger photos at regular intervals.

Manual camera settings are crucial! Over time a scene you are photographing might change in brightness or colour; these changes may cause a dramatic changes to the camera settings between photos taken in an automatic camera mode. Take for example a time lapse film of cars driving past, if a bright red car is photographed, it may change the colour balance, cause all the other objects in the background of the photo to also change in colour, and coause these objects to flicker.

Tripod

No one wants to hold a camera absolutely still for several hours taking photos, and sometimes a table does provide the desired angle or is simply not practical. With a tripod you can place your camera at the correct angle to shoot your scene without the camera moving out of place over time.

Large Memory Card

A 2 minute time laspe film typically requires 2880 photos, and to make sure that you don't need to interrupt your filming to change your memory card you should use a memory card with plenty of spare space. An 8 mega-pixel photo can take up about 1.8 MB of storage, which means that 2880 photos would require a memory card larger than 5.3 GB.

3. Choosing a suitable scene for a Time Lapse film

You can film a time laspe movie of almost anything, the sky is the limit. Below are only some examples of thing that you could choose to film:

• Clouds (during the day or lit by city lights during the night)
• Boats moving though the water
• Traffic on highways or intersections
• Hot Air Balloons
• Sun Rise or Sun Set
• Stars in the night sky
• Snails
• Market places
• Smoke Stacks
• Construction
• Packing and Moving house
• House plants

You may even find that you'll notice the most unexpected things occur in your time lapse film, such as plant movement, or bizarre cloud motion. You'll never know unless you give it a try!

As with all photography it is really important that you seek the permission of the people or owners of property before filming them.

4. Camera settings that may improve the quality of the time laspe footage

Here are some camera settings that you may want to keep in mind when making a time lapse film

• Interval Time
  Make sure that your photo interval time is set to something reasonable, once per five seconds to ten seconds is perfect for most cloud time lapse films, If the time interval is too long then things may move too rapidly in your time lapse film when played back. Some scene such as stars in the night sky suit a time lapse interval of 30 to 60 seconds. Feel free to experiment with this for your films to see what suits best.
• Manual Focus
  Many cameras have automatic focus which means that for each new photo the focus is re-adjusted and can cause your film to have a slight jitter due to the focus of the camera changing slightly for each frame of your movie. If possible, it is worth setting the focus manually.
• Manual Colour Balance
  Most cameras also automatically adjsut the colour balance for each seperate photo, this may be a problem if your time lapse scene changes in colour, like electronic billboards, or televisions, or grey sky to blue. These automatic changes to the colour balance of the film will introduce flickering so it is worthwhile manually setting the colour balace. (see you camera manual details or ask your local camera store).

If you intend to do a time lapse film outdoors in cold weather, firstly make sure that the camera is able to operate in those temperature conditions (see manual or ask at your camera dealer); secondly your camera should be slowly brought to a similar temperature to the outdoor temperature to prevent condensation forming either inside or outside the camera. Condensation will not only ruin your time lapse film but may also permanently damage your camera.

5. Filming a time lapse movie with a digital still camera

So there you are, outside on a cold morning ready to take photos. Remember that that to capture footage for a 24 second time lapse will take about an hour to shoot (with a five second time interval played back at 30 frames (or photos) per second, so it is importanr that you have somewhere nice to sit to read a book or newspaper and that you are appropriated dress and protected from the elements (including sun screen). If you are outdoors it is worth knowing how long your camera battery might last (is it 1 hour or 3 hours, sometimes you may only find this out though practice). It may be worthwhile carrying some spare batteries.

Some things that you could do to improve battery life of your camera during a time lapse photo shoot include:

• turning off the LCD screen on your camera, if this feature is supported;
• using manual focus, not only does this improve the image stability, but it will prevent the camera from refocussing for each seperate photo;
• Make sure that your flash has been turned off;
• Try to maximise your shutter speed so that the camera CCD is on for the least amount of time possible. (However in some situations, like night time or using  a neutral density filter, it will be desireable to have a longer exposure time).

6. What to remember when tranfering the photos to your computer

A time lapse film can consist of thousands pf high quality photo, using potentially lots of space on your camera's memory card and ultimaately lots of space on your computer! It is important to make sure that you have enough free memory on your harddrive to contain all the photos, and to hold the HD movies that you will create. A rule of thumb that I use (but this may not suit your needs) is that if I have a memory card of 5GB I'd need atleast 10 to 15GB of free harddrive space to create a time lapse film.

Many cameras allow you to plug a cable from the camera to a USB port on your computer. From personal experience this can be a rather slow way to transfer all of you thousands of photos and you camera may need to be on the whole time to allow all of the photos to transfer.If your camera has an SD or other memory card, it may be worthwhile having a seperate card reader that plugs into a USB port, or if you're lucky, you computer may have a card reader already built-in.

Personally I have successfully used both Picasa (for Windows Vista/7 or Mac OS X) and iPhoto (for Mac OS X) to handle photos I have taken for time lapse films. Remember that you will need to be patient when tranfering the photos and it is always worthwhile making sure that you do not delete your photos from the memory card until you are satisifed that they have all be transfered correctly without error.

7. Converting the photos into a video

This is the most important part of the process, without converting the photos to a video you'll just have a thousands of photos. Here are some brief notes for making a timelapse movie using eith Picasa (for windows or Mac OSX) and QuickTime 7 Pro (MacOS X)

Picasa (click here to download)

Making a time lapse in Picasa is relatively easy, all you need to do is locate the photos you have imported in Picasa and click the Create a movie presentation (the movie clip icon). You will then be able to choose the settings for creating your film. In the transition style box you will be able to select the time lapse option, below this option you'll be able to select the frame rate (or the number of photos do be displayed per second). To ensure that the animation is smooth, a frame rate of 24 to 30 fps will be desirable. Once this has been done, all you'll need to do is to click Create Movie. The process of making the movie may take several minutes so be patient. Once it is done, that's it, you've made a timelapse film!! You can then share the video with friends, sell it as stock footage, or you can further edit it using iMovie or Windows Movie Maker.

QuickTime 7 Pro (click here to download and buy)

QuickTime 7 Pro provides a sophisticated, yet affordable approuch to creating films from time lapse photos. To make a time lapse film using QuickTime Pro 7, simply load the photos into QuickTime by:

1. Clicking the File Menu
2. Selecting Open Image Sequence ...
3. Selecting all the timelapse photos in the open dialog box.
4. Selecting your desired frame rate (typically 24 fps)
5. Once the images have been loaded you can select Export ...
6. In the export dialog you can select where you would like to save your film, you can also choose the movie format from the Export dropdown menu (AVI, QuickTime, etc), clicking Options ... allows you to adjust the setting for the selected export format.
7. Once you have selected Save the film will be exported and ready to be played within several minutes.

Making time lapse films is a great hobby that you can have a lot of fun with, all you need is time and patience (and a camera and some software).