The Advanced Art of Stop-Motion Animation: Digital Cinematography: Part 1
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.