Frame Rates
Current DSLR cameras offer a range of frame rates depending on which camera you buy or rent. Let’s talk for a moment about the standard frame rates in both film and video production. We call these frames per second (fps). These are the most common, or standard, frame rates:
24 fps is the standard rate at which motion-picture film gets run through the camera. So, any movie that is shot on film that you see in the movie theater was shot at 24 fps and is the holy grail of the “film feel” of your footage.
25 fps is the standard in most of the world (outside the United States and Japan) for video broadcast. This is close to the “film look” and was widely sought after in video cameras in the United States for filmmakers looking to get away from the 30 fps look of U.S. video cameras.
29.97 fps is the standard for broadcast in the United States. Most people refer to this as 30 fps, but there is a huge difference between 30 fps and 29.97 fps when it comes to broadcasting or viewing your footage in traditional formats (that is, TV, DVD, VHS, and so on).
30 fps is the standard more or less for web video. On the Web, there are no rules for frame rate. The Canon 5D Mark II originally was able to shoot only 30 fps and was limited to web-only video or complicated transcoding that doesn’t always work without problems.
Slow motion would be any frame rate greater than 30 fps. The two most common frame rates on DSLR cameras are 50 fps and 60 fps. This means you are recording double the number of frames as you would at 25 fps or 30 fps, and you can (in post) play these shots back at half speed smoothly, giving you slow motion.
fps and p vs. i
Many times fps is not listed next to your frame rate. Instead, you will see the frame rate of 24, 30, and so on, and either the letter i or the letter p will follow it. For example, if you want to shoot at 24 fps, you can select 24p, which stands for “24 frames per second progressive.”
When you see 60p vs. 60i, the p stands for “progressive,” and i stands for “interlaced.” Interlaced video records every other line, whereas progressive records a full-frame image. For example, 60p means you are recording 60 full-frame images each second, whereas 60i means you record half an image each second, so you end with a total of 30 full frames.
You might hear a few other terms related to frame rates. For example, NTSC stands for “National Television System Committee” and is the analog television system used in North America, South America, South Korea, Taiwan, Japan, Burma, the Philippines, and some other Pacific islands. NTSC has been the standard for more than 50 years in broadcast media in the United States and represents a 4:3 aspect ratio (think of the standard TV image, that is, non-wide-screen models) and a frame rate of 30 fps (also 29.97 fps). Both 30 fps and 29.97 fps are referred to when talking about NTSC. Although 30 fps was the initial standard for NTSC in 1941, in 1953 with the introduction of color television, the committee required a slight reduction in frame rate down to 29.97 fps. This reduction was needed because of visible interference with the chrominance signal and the sound signals over the airwaves. (In June 2009, the United States transitioned from analog to digital transmissions, and the new standard is called ATSC, which includes the digital formats 16:9 and 1920×1200 resolutions.)
ISO Settings
What is ISO? ISO represents how sensitive the image sensor is to the amount of light available. The higher your ISO, the more sensitive the image sensor is, thus increasing your ability to get shots in low-light situations. By raising your ISO rating to shoot with less light, you will be adding more noise or video grain into your image. Just note that often when you change one setting you are not changing just one thing – likely you are affecting something else by your choice. This is why it is critical to know all the basics and how they all interact so you can make sure you understand and predict what the end result will look like in the video image.
ISO is mostly an issue when you are shooting in low-light situations. If you are outside on a bright, sunny day or if you light your scene, you will be able to stay with a lower ISO. Think of ISO as a tool to help you capture an image if you aren’t in ideal conditions or if you don’t have enough lights to illuminate the scene.
Which ISO settings are available will differ from camera to camera.
If you have a still-film background, you may be more familiar with this being referred to as the ASA rating. ISO is the digital-photo equivalent of a film stock ASA rating.
As the famous quote states, “You can’t have your cake and eat it too.” There is a trade-off to high ISO settings: noise. When you boost your sensor’s sensitivity by selecting a higher ISO, you are enabling the camera to record a fainter light signal. By enabling the camera to record a fainter light signal, you, at the same time, are allowing the camera to record the fainter noise signal. Noise is defined as any signal that is not attributed to the light from the subject you are shooting. Noise appears as colored pixels usually most visible in the shadows and dark areas of your footage.
The sensor in your camera is an analog device and as such will create some noise itself in capturing your footage. This, coupled with the increased ability of the sensor to capture the light signal and noise signal, creates the visible noise in your captured footage. If you ever shoot high ASA film stock, then you have grain instead of noise; in general, film grain is acceptable, whereas digital noise is considered bad.
Your sensor size and camera manufacturer determine the range of ISO settings available on any given camera without being affected by noise (at least noticeable noise). The signal-to-noise ratio (or the S/N ratio) is the amount of light (signal) captured in relation to the amount of noise captured. This is why, in general, the larger the sensor, the less noise present in your footage. The reason for this is the number of pixels and their density on the actual sensor. Look at various camera models, and you will see that the manufacturer has placed a rating of 8 megapixels (MP), 10 megapixels, 12.1 megapixels, and so on for the sensor of those cameras (a megapixel is 1 million pixels).
This can be a bit deceiving, though, because it’s possible for two cameras – one that has a crop sensor and the other a full-frame sensor – to have the same megapixel count. In this case, the manufacturer has crammed the same number of pixels on the smaller sensor as on the larger sensors. This causes the pixels to be much closer together and affects how much signal (light) can be captured through each pixel. For instance, consider an 18 MP Canon 7D (Canon APS-C sensor) and a 16 MP Canon 1D Mark IV APS-H. You might think that because the 7D has more megapixels, it would yield a better image. Actually, the 1D Mark IV, with only a 16 MP count, will yield a better (less noisy) image because the pixels are less densely packed on the larger sensor.
So, you cannot look just at the megapixel count; you also need to look at the sensor size and the density of the pixels in the camera you want to use. The best possible situation is a full-frame sensor with a high megapixel count. If you are looking at cameras that share the same sensor size but have different megapixel counts, you may want to rent both cameras and shoot some footage to test the noise signals and see which one gives you the better image for your project.
Features of SLR Lenses
The lens is the “eye” of your camera; what is captured in the lens is what will end up on the screen. Shooting with a DSLR opens up the world for most videographers who were limited by a single lens or complicated adaptations, and filmmakers are curious to see how a familiar lens interacts with the new system.
Because the choice of lens is the single most important decision you will have to make for every single shot, it is important to start with the relevant basics. Here we will talk about the lens choices and how they affect your final footage.
Aperture, f-stops, and t-stops
Aperture (the measure of the space that light passes through in the lens) is measured in f-stops. An f-stop is a ratio or fraction, so smaller numbers mean more light. Often lenses are considered fast or slow: a lens with a low-numbered minimum f-stop