In the latest excerpt from The Advanced Art of Stop-Motion Animation, Ken A. Priebe begins his discussion on digital cinematography.
Stop-motion photography is not just one image, but rather a series of images that create motion when strung together. Shooting stop-motion relies on having the following things: a story to tell, puppets to tell that story with, and a camera to be the eyepiece for that story. If you have the first two nailed down, reading this chapter will help you focus (no pun intended) on what you should know about your camera, some details on how to shoot with it, and some practical effects you can try.
When stop-motion was shot on film, each frame would exist as its own separate image, strung together on a strip of 8mm, 16mm, or 35mm film (Figure 4.1). The film would be registered with a series of sprockets that push the strip of film through a gate in front of a square window blocked by a shutter. Exposing one frame of film with the touch of a button would open the shutter and expose light through the lens onto the film. Then, the sprockets inside would advance the filmstrip to the next unexposed space for the next image to be captured. Each image was essentially a separate photograph with its own established focus, exposure, color, and lighting. These elements would essentially be a continuous tone, and the features on a film camera could be set manually, although fluctuations could happen because of uneven shutter speed, changes in temperature, or the film moving around in the gate. There was no way to make sure each frame was consistent with the next one. The result of the whole process was basically a series of still images on the strip of film that would exist only in negative form until it was sent to a lab to create the positive print. Looking at the strip of film itself, all of the separate images are visible, so an editor can see exactly where scenes begin and end, and the images can be re-arranged and spliced together.
As film use declined over the years and was replaced by video, the most popular method for stop-motion became using a MiniDV camcorder with an IEEE-1394 Firewire connection (Figure 4.2) that provided a live feed to a computer with frame-grabbing software. The video camera basically acts as an “eye” and feeds a constant live image into the software, so if one moves a hand into the frame, this should all appear in real time on the computer monitor as well. The software then grabs separate still images from the live feed each time the animator hits the capture button. The flexibility of this method provides instant access to the images for preview purposes and playback. However, even with an HD camera and frame averaging provided to improve the quality of each frame, the image being fed into the computer is essentially a compressed image, and there may be limits to how much resolution can be attained for high-quality broadcast. Watching the animation play back on a computer monitor might look fine, but if it is meant to be blown up on a huge screen at a film festival, the image quality might not be as strong as it should be. Of course, some software does have frame averaging and HD capabilities to help with this.
Despite these challenges to work around, using a live Firewire feed is still a perfectly valid way to shoot stop-motion. However, even though Firewire cards and converters are still on the market for installing into computers, most video cameras no longer come with the Firewire output or cable included. Video camcorders at average consumer prices (or higher) now typically shoot movies onto a hard drive, and a USB connection is used to transfer the video off the camera. Flip Video cameras operate on the same principle, allowing you to shoot video easily in the palm of your hand and upload movies as AVI files directly to your computer. From there, you can burn your videos to DVD or upload them straight to YouTube. More and more standard hard-drive camcorders also shoot in HD, which is quickly becoming standard for all broadcast media. This is all fine if you are shooting home videos of your friends, your kids, or your cat playing the piano for YouTube. However, for stop-motion it presents a problem because a USB connection from these cameras (Figure 4.3) will not provide you with a live feed for your frame grabber. Without a live feed, you cannot use the onion skin or frame-toggling features that frame-grabbing software allows you to take advantage of to help keep your animation registered.
Meanwhile, as Firewire outputs on computers and camcorders have become harder to find, there has been an explosion of popularity of digital SLR still cameras in the past few years. Gone are the days of taking pictures with a film camera, dropping off the tube of film at the drug store, and waiting an hour for your photos and negatives to be ready. Tiny digital cameras that allow you to point, shoot, and get your pictures instantly for uploading to your computer, printing, or posting online have taken the world by storm. (I don’t even remember the last time I took a picture using film.) Then came the digital SLR camera (Figure 4.4), which had the appearance and image quality of the more professional film cameras, but allowed for manual controls and creative freedom in a digital universe. Now it seems like everyone has a digital SLR camera because they have quickly become more affordable for the average consumer.
Along with this trend has been the realization that one can shoot stop-motion with a digital SLR camera. Part of the appeal of shooting stop-motion this way is that it essentially takes the process back to its roots of shooting a string of still images on film. After taking a series of high-quality still images, the next step is to download them straight to the timeline of an editing software program and play them in sequence. The manual controls for image quality make the stop-motion frames look as sharp and clear as a film print, or potentially even better.
However, this has presented another problem: by itself, a digital still camera will not provide a live feed for your frame grabber. The solution in this case is to mount a camcorder next to the SLR or attach a tiny spycam or webcam to the viewfinder, and use that image for the live video feed. The animator can then use the live feed image to utilize the frame-grabber’s functions of onion-skinning and toggling, while at the same time capturing their actual frames in high-resolution with the SLR camera. As long as you remember to take a picture with each camera, this gives you the best of both worlds. This method is still a common way to shoot stop-motion, but even better is the fact that digital SLR cameras now are available with an HDMI or USB live video feed (Figure 4.5). They are more expensive than the lower consumer brands without live preview, but as they rise in popularity, the price continues to come down and become more affordable. Before too long, digital SLR still cameras with a live video preview function could likely become the standard for personal video use (including filming your cat for YouTube). The more affordable these options become, the better it will be for everybody. The other convenient factor to the digital SLR camera’s popularity has been the development of several stop-motion software programs to communicate directly with the functions of certain Canon or Nikon SLR cameras. At this time, the latest versions of Stop Motion Pro and the newly popular software Dragon Stop Motion have this functionality, and many more could easily come onto the market before too long. Software programs now have the capability to work with the manual controls of the camera from within the computer, capture the HD images directly into the timeline, and provide a multitude of other convenient functions for digital workflow.
This book is not intended to focus on any particular software program (although a few specific ones are mentioned throughout) because this information will always change as new versions come out. Whichever software you use is up to your own preference, operating system, budget, and reasons for shooting stop-motion in the first place. Indie stop-motion filmmakers all have different financial situations, living conditions, and responsibilities outside our puppet-pushing; not everyone may be able to afford a fancy digital SLR camera with live video. They also may not necessarily need a super-high-quality image if they are simply doing stop-motion tests or learning basic student-level animation. A webcam can still provide a live feed for a simple image through a USB, but most of them won’t allow for manual control or a suitable image for a semi-professional production. A MiniDV camcorder with a live Firewire output had always been a good compromise, but being without this option puts stop-motion filmmakers on a budget in a difficult transitional stage. Hopefully this will pass, and another simple method will come onto the market that allows all filmmakers to make their films look the best they can at any budget. The software you are able to use may also be determined by your camera. If your version of the software does not support the live-feed option for your digital SLR camera, you are limited to using a webcam or an SLR with a spycam, or trying to find a used DV camera with Firewire (perhaps on eBay). Another option may be to use a special video adapter or a video capture converter like a Canopus, which coverts an analog video signal to digital for a live feed. With a bit more simple technology and a little creativity, you can find other solutions that work to achieve your purposes, according to your budget constraints or shooting needs.
Independent animator Ron Cole describes his method for connecting his stop-motion set-up as follows:
I have a Lumix SLR camera, which has manual controls and a good image. My camera is not compatible with the Dragon software I’m using, but for the end product I use the following method: I have a live feed coming from the camera to an analog-to-digital converter into my software. The live feed is a bit grainy, but hi-res images are coming in through my camera’s Eye-Fi card, which is a memory card that can upload images wirelessly to my computer. Dragon has a feature called “folder watch,” which takes an image from the Eye-Fi card and replaces the live feed image in the timeline. This gives me the ability to back up after taking my picture to check the hi-res image. This is very useful when I’m shooting stop-motion to match up with a live-action shot and need the puppet’s foot to be in the right place, for example, after taking the exposure. Since the grainy image coming from the viewfinder is harder to see, it helps to be able to double check the alignment of my puppet after capturing my hi-res images into the timeline.
As a stop-motion filmmaker, you can also decide for yourself whether a live feed is necessary at all, especially if you have a bit more experience with animation. If you are shooting frames with an SLR or any other type of still camera, you can simply load the still images into a timeline on your computer as you shoot. The only computer function that may be available to you is the ability to advance through your frames to check the registration of your animation, but only after you capture each frame. As far as the positioning of your puppet is concerned, you are shooting blind, as you would be if you were shooting on film. Without the ability to toggle between your last stored frame and your live frame in your computer, the exact reliability of your puppet being properly registered is essentially done by observing the puppet on set and seeing the movement in your head. The difference is that after you capture your frame, you can look at your timeline and advance your frames to see whether the animation is doing what you want. If there is a problem with the registration, lighting fluctuation, or otherwise, you simply delete the frame you just took, fix the problem, and re-shoot. This is a different method of frame toggling with an extra step, but it still does the job. The only other convenience not offered without the live feed is the onion skin, but you can work around this by using the old-school method of drawing on the computer monitor with a dry-erase marker. Overall, it’s up to you and how spoiled you have become by the luxury of the live feed. If you are experienced enough in stop-motion to know instinctively where your puppet should be without using these tools, you can likely get by without them. With your camera, simply shoot blind, take your pictures, load them up, and watch the magic happen. (While you’re at it, you might as well break out those rusty surface gauges, too!)
Whatever method you decide to use, it does look like the digital SLR still camera is continuing its popularity, so this chapter will mainly focus on shooting in this method for creating an advanced, high-quality stop-motion film.
Digital Camera Basics
With a digital SLR camera, the images are not captured onto a strip of film, but rather onto an image sensor. The sensor is made up of millions of pixels, which are like tiny buckets that gather light. The light is essentially converted from analog into electric photons in digital format, and this will typically give increased quality through a full-frame sensor. The resolution of the captured image is measured in megapixels; the resolution increases based on the megapixel number. Most digital cameras range from 8 to 21 megapixels. When a picture is taken, a mirror (which reflects the image seen through the viewfinder) flips up, light enters through the lens and hits the sensor, creating an exposure that is sent through a processing engine to create a digital file on the camera’s memory card.
When taking these individual images, you have the option of saving them either as JPEGs or in RAW format. JPEGs are a relatively standard format, even for compact digital cameras, and can be captured in high quality, although they are compressed images. They are only 8-bit, but perfectly suitable for loading into a video timeline for editing and giving you this flexibility. RAW files are unprocessed and essentially serve as a digital negative, going up to 14-bit and giving you an expanded range for editing in post-production. RAW files imported as a sequence into your editing timeline or Adobe Photoshop will give you more flexibility for changing brightness, correcting color, or adding digital effects. The main thing to realize is that it also means each individual frame will have a significantly larger file size and will require more hard-drive space to back them up. Shooting in RAW format is probably best for a professional film that is commissioned or intended for HD screening or a film festival. Depending on your intentions for shooting, you can either shoot in both formats (RAW for high-quality edit, JPEG for back-up and simple playback) or just stick with whatever suits your needs.
The lens you use can vary greatly, but its quality will have a great impact on the quality of your image. Shooting at a small scale for stop-motion does not require a telephoto lens since you are typically much closer to your subject. Most stop-motion filmmakers typically use any lens in the range of 24mm to 85mm (or higher) and follow the recommended practice of interchanging lens brands with camera brands. One of the biggest challenges in shooting stop-motion with still cameras is the flicker caused by fluctuations between exposures. Often this will be caused by outside elements, such as uneven wattage or gradual dimming of the lighting set-up, but can also be caused by fact that most digital SLR camera lenses have an iris that defaults to being open and only moves into the setting you want when you take a picture. Using a truly manual lens from an older camera is one way to help keep all your images at the same exposure.
The settings for the basic exposure elements of your camera should all be set to manual controls when shooting stop-motion to alleviate the fluctuations between separate frames that can result from using automatic settings. The essential elements to keep on manual settings include focus, aperture, shutter speed, white balance, and ISO.
The ISO determines how sensitive your image sensor is to light. On film, the ISO would be pre-determined by the type of film stock being used, but digital ISO can be adjusted for each frame and shooting situation. If you are shooting a dark scene for your stop-motion project, increasing the ISO will increase the sensitivity to light and allow for a slower shutter speed. However, it will also create more digital noise, which is one of the shortfalls of digital photography. Heightened sensitivity on the sensor causes heat build-up and will create chunky blotches in low-light areas and shadows, unlike film grain, which is smoother and moodier. This was one of the challenges faced on Tim Burton’s Corpse Bride, which had many scenes with low light, so dark sets were often over-lit and adjusted in post-production. A lower ISO setting combined with a shorter shutter speed will typically create less digital noise, but ultimately the relationship between noise and your manual settings depends on your camera. In most cases it’s best to keep the ISO setting lower; most stop-motion filmmakers keep it around 100 to 200.
Aperture and Shutter Speed
Controlling the aperture affects the amount of light coming into the camera through an iris-shaped mechanism inside the lens. Capturing light through exposures in photography is measured by f-stops (Figure 4.6), which are either half or double the amount of light in the previous stop. To increase aperture by one f-stop, for instance, means doubling the amount of light hitting the sensor.
The shutter speed consists of how long the shutter is open and exposes the sensor to light. Therefore:
• Wide aperture (lower f-stop number) = more light = faster shutter speed.
• Small aperture (higher f-stop number) = less light = slower shutter speed.
Placing a digital light meter directly in front of your central focus (like your stop-motion puppet) and pressing its meter button will help you determine which f-stop and shutter speed to use for getting the right exposure for the lighting situation you are using. This is pretty straightforward if you just have one puppet in a long or medium shot on stage for a simple scene. For a composition that requires a bit more depth to the puppet’s surroundings, there are a few other things to consider. Whatever is closest to your light source may have a lower stop than anything that is farther away in the background, so you may want to take a reading for both your foreground and background, and stop your camera at a point in between.
Depth of Field
These camera settings will also be affected by the depth of field you want for your shot. Depth of field refers to how much of the distance of your composition is in focus. For stop-motion, as opposed to live action, everything is scaled down to miniature size, including the distance between your camera and your subjects. In most cases you don’t want the audience to feel like they are watching a miniature set, but rather a world they will recognize as having a natural sense of distance. This natural feeling of distance will be accomplished mostly by having a wider depth of field where more elements are in focus. A shallow depth of field will mean that if you focus on the central part of your composition, the background and surrounding elements will be blurry. Shallow depth of field is typically caused by a lower f-stop and faster shutter speed, and a wider depth of field by a higher f-stop and slower shutter speed. For a happy medium in a basic animation scene, most stop-motion filmmakers set their camera in the area of f11 with a shutter speed of 1/2 to 1 second. Stopping at f16 or f22 will create a more extreme depth of field, and stopping at f8 or lower will soften the background. It all depends on the mood you are going for when telling your story.
The illustrated examples shown here show how different moods and effects are created through camera settings, and also through composition of the shot itself. For a happy, light, or comedic scene (Figures 4.7 and 4.8), the composition is usually flat, with the camera centered and perpendicular to the set. Figure 4.7 is shot with a shallower depth of field, which blurs the character in the background. Figure 4.8 is shot with a wider depth of field, so the whole scene is in focus and the faces of both characters are much clearer. This clarity is important for a playful scene like this and communicates the relationship between the two characters.
For a creepy, dark, or dramatic scene (Figures 4.9 and 4.10), the composition is usually shot at more of an angle to give a more unsettling effect. Figure 4.9 is shot with a shallower depth of field, blurring the background character and heightening the mysterious mood. Figure 4.10 is shot with a wider depth of field, bringing both characters into focus.
Depending on what your story calls for, there will be times when you may want a shallower depth of field and times when you won’t. It helps to know how to use your camera as a story-telling tool to get the effect you want.
White BalanceWhite balance is a function that removes certain kinds of color casts created by different light temperature situations. Color temperature of light is measured by the Kelvin scale, which is based on the color that would be cast by an object as it is heated. Higher temperatures will appear cooler; this seems backward, but it’s based on the fact that although we think of objects as being red or orange when they get hot, they actually will go blue to white the hotter they get. Therefore, warm-feeling lighting situations, such as candlelight, have the lowest light temperature (1,000 to 2,000 K) and cool-feeling lighting, such as an overcast day, have the highest light temperature (9,000 to 10,000 K). In any lighting situation, our eyes can always recognize whether an object is white, but digital cameras do not have this interpretation, so improper white balance setting will create unwanted blue or orange casts to an image. Simply put, you need to tell your camera what is white so it has a reference point for it. For any photographic situation, including stop-motion photography, custom white balance is typically set by placing a white card in front of your entire frame and allowing the camera to set the white balance to the color temperature of your lighting situation. Most cameras will also have pre-set white balance settings for certain lighting scenarios, such as tungsten, daylight, overcast, and florescent.
In terms of how this relates to stop-motion, in most situations you would not be shooting outdoors, so higher color temperatures would rarely be taken into account. In most cases you are shooting indoors on a miniature set using artificial light. Most lights used for stop-motion have a quartz or tungsten filament, which has a color temperature of up to 3,500 K. To achieve a particular mood for your scene, you can play with the white balance to make your shots appear warmer or cooler, if you feel this adds some atmosphere to your film. A standard set shot in tungsten can be made to look warmer by setting the white balance to daylight (about 5,000 K) and giving it a more orange cast (Figure 4.11). For a sad or creepy mood, letting in more light and balancing to a lower tungsten setting can add a darker blue mood to your scene (Figure 4.12). In many cases this may seem like extraneous tweaking to your imagery, but mostly it helps to know how to set the balance properly so that you also know how to control the way your film should not look. Adjusting the white balance should ideally be done on set if you are shooting JPEGs only, but if you are shooting in RAW format, you also have the option of changing the white balance in post-production.
All things considered, there are endless combinations of settings and scenarios for making your stop-motion films look a certain way, and they will always change depending on an equally endless range of factors. Within whatever means you have, set things up until they look good enough to serve your story.
(Photos for this section shot by James Emler. Monster puppet by Emi Gonzalez, and hamster puppet by Frida Ramirez.)
Ken A. Priebe has a BFA from University of Michigan and a classical animation certificate from Vancouver Institute of Media Arts (VanArts). He teaches stop-motion animation courses at VanArts and the Academy of Art University Cybercampus and has worked as a 2D animator on several games and short films for Thunderbean Animation, Bigfott Studios, and his own independent projects. Ken has participated as a speaker and volunteer for the Vancouver ACM SIGGRAPH Chapter and is founder of the Breath of Life Animation Festival, an annual outreach event of animation workshops for children and their families. He is also a filmmaker, writer, puppeteer, animation historian, and author of the book The Art of Stop-Motion Animation. Ken lives near Vancouver, BC, with his graphic-artist wife Janet and their two children, Ariel and Xander.