We intuitively understand focusing a lens, simply by experimenting until an image appears sharp. But what does it really mean technically? Even professional photographers often don't know about the circle of confusion and the reasons why depth of field is as much a product of the camera sensor as it is the design of the lens. This lesson explains focus in simple terms, and shows why a focused lens captures a range of subjects sharply rather than one precise distance from the camera.
- When cameras focus, light from the subject shines…through the lens where it's focused on the photo-sensor…in a digital camera or…the film surface in an old-style film camera.…In either case, there's a minimum grain size.…In the case of film, that grain size would be…the particles of light-reacting dye.…In the case of a digital camera,…it's a single photoreceptor.…When a single point of light lands perfectly…within a photoreceptor, it's in focus.…When it doesn't, it's not.…
It's as simple as that.…But what if that single point of light could be…even more in focus than a single photoreceptor?…Well, in that case it could never look any more…in focus than a single photoreceptor…and it would look exactly as sharp as it did before,…and that's depth of field.…When you focus a lens there's actually a range…of focal distances that are as sharp as…the light sensor can see.…When you open up the lens by using a lower F-Stop…or T-Stop you widen the area…the light is shone onto on the sensor.…
Truly in-focus items will still look in focus…
Get ready to remove the mystery behind terms you've encountered. If you work in a creative profession, this can enhance your command of the tools you use. Learn what a pixel really is, what color channels are, and what audio frequency is. Discover how color channels, bit depth, and video frame rates work. Find out the difference between codecs and file formats, and how compression is involved. By the end of this course, you'll know how to answer common client questions—like, whether a logo should be supplied in vector or bitmap form, and more.
- What is a pixel?
- Aspect ratios
- Bit depth
- Alpha and transparency
- Light and color channels
- Color modes: RGB, YUV, CMYK
- Camera depth of field
- Chroma Key and Luma Key
- Blend modes
- Color wheels, vectorscopes, and waveforms
- Video compression and codecs
- Frame rates and timecode
- File formats
- Audio amplitude
- Capturing audio tone as frequency
- Audio timing using the phase
Skill Level Beginner
Learning Video Production and Editingwith Rob Garrott20m 37s Beginner
Video Foundations: Cameras and Shootingwith Anthony Q. Artis2h 58m Appropriate for all
Introduction to Video Dialogue Editingwith Ashley Kennedy3h 14m Appropriate for all
1. How Do Computers Think?
2. How Cameras and Computers Think about Color
3. The Language of Color
4. The Shape of Your Picture and the Speed of Your Video
5. Storing Everything (Codecs)
6. Color Wheels, Vectorscopes, and Waveforms
Understanding waveforms2m 39s
7. Making Changes
8. Audio Made Simple
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