Hi Everyone,
Below is a plethora of
information and explanations on understanding the fundamentals of
lighting for
video and using
video cameras. If you could please look over this I think it will
benefit everyone to more deeply utilize cameras and
lighting for its emotional,
textural and spacial potentials.
I hope this helps answer your questions and generate some ideas.
Dominika
What is COLOR TEMPERTURE?
The technical definition of colour temperature is full of terms like
"black-body radiator" and "chromacity space" - in short, it's very
confusing, very boring, and above all leaves you feeling even more
baffled than before.
In layman's terms though, different
light sources produce different
colored
light. For example, a candle emits a reddish
light, while the
midday sun's rays have a blue tint. These different colours can be
expressed using a number, and this number is known as the colour
temperature.
Colour temperature is measured on the Kelvin scale, which is denoted by
the letter "K" or the word "kelvin" after the number. However, this is
largely irrelevant - the only part we're interested in is the number.
How is Colour Temperature Used in Photography->or Video in our case?
You're probably wondering how all this affects you and your images.
Well, the human eye is excellent at adjusting to different colour
temperatures, which means that to you and me objects appear roughly the
same colour whether they're outside in the sun or indoors under a
lightbulb.
You can use colour temperature to keep the colours in your photos looking accurate and natural. Image by
Jose Guzman Garza.
Digital cameras aren't as good at adapting as we are, and as a result
they "see" objects as being different colours depending on the
lighting.
This can lead to our photos having a colour cast - that is, an overall
blue or orange tint - which makes the shot appear unnatural and
unpleasing.
Thankfully cameras allow you to correct for these colour casts by
telling them the colour temperature of your scene. This is done using
the
white balance setting
- simply tell the camera what type of
lighting your scene has
(daylight, shade, tungsten etc), and it will use an appropriate colour
temperature.
For even more accurate control, some cameras allow you to program in an
exact colour temperature in kelvin(
the Canon 6d for example does just this). You can get a precise value by
using a colour temperature meter, or by taking a photo of a white object
under the same
lighting and letting the camera calculate the
temperature. Alternatively you can make an educated guess using the
chart below.
A
visual & written explanation of f-stops(aperture), shutter speed
(how quickly or slowly your shutter opens) and ISO (sensitivity to
light) when using film the film will contain a sensitivity number ISO
-100, 200, 3200 etc in video you can manually set the desired
sensitivity of your camera's sensor, the 6D provides users with more
control in this arena.
- Shutter Speed -the length of time a camera shutter is open to expose light into the
camera sensor. Shutter speeds are typically measured in fractions of a
second, when they are under a second. Slow shutter speeds allow more
light into the camera sensor and are used for low-light and night
photography and video, while fast shutter speeds help to freeze motion. Examples
of shutter speeds: 1/15 (1/15th of a second), 1/30, 1/125 etc
- ISO-
the level of sensitivity of your camera to available light. It is
typically measured in numbers, a lower number representing lower
sensitivity to available light, while higher numbers mean more
sensitivity. More sensitivity comes at the cost though, as the ISO
increases, so does the grain/noise/pixelation in the images. When
working with video it is crucial to note that bumping up your ISO
will cause a more noisey or pixelated image. Working with the 5d, 6d or
7d it is recommend to stay under 640. The general consensus is between
100-640 for more crisp images. Though I feel this is a personal choice
depending on the look and texture you desire
- Aperture- a hole within a lens, through which light travels into the camera
body. The larger the hole, the more light passes to the camera sensor.
Aperture also controls the depth of field ,
which is the portion of a scene that appears to be sharp. If the
aperture is very small, the depth of field is large, while if the
aperture is large, the depth of field is small. In photography, aperture
is typically expressed in “f” numbers (also known as “focal ratio”,
since the f-number is the ratio of the diameter of the lens aperture to
the length of the lens). Examples of f-stop numbers are: f/1.4, f/2.0, f/2.8 - f/22.0 etc.
VIDEO LIGHTING TECHNIQUES
Tungsten vs Fluorescent
-----Tungsten, sometimes referred to as "hot lights" because they emit
heat,
are skewed to the lower end of the light spectrum, hence they look
"warmer" or more reddish without proper filtering. (Also known as a
daylight look) One major problem with tungsten is that they are not
reliable over a period of time as
their color will change as they age and variations in voltage will
also change the color output, that is why some people prefer halogen.
Fluorescent lighting is skewed towards the blue end of the spectrum, so
without proper filters, you get a "cool" or blue/green color cast to
your images. On the positive side, they are not hot as tungsten. It also
flickers which may or may not be a desired effect.
RULE OF THUMB WITH FRAME RATE AND SHUTTER SPEED :
As a rule of thumb, you want the denominator of your shutter speed
to be approximately double the number of frames per second that you are
recording. In other words, if you are recording at 30 frames per second, you want your shutter speed to be 1/60th of a second.
Even though we generally set the denominator of the shutter speed to
be double the number of frames per second, you can achieve some
interesting stylistic effects by straying from the norm. Shutter speed
can have a very noticeable effect on the look of your video,
particularly when it comes to motion. A fast shutter speed such as
1/400th of a second will produce a series of crisp frames that have a
choppy look when played back. A slow shutter speed such as 1/30th of a
second, on the other hand, will produce a series of slightly blurred
frames that have a smoother look when played back.
FRAME RATES: 24, 25, 30, 60 :
The
number of frames per second. If you are for example planning to edit
your video in slow motion you may consider shooting it at 60 f/ps to
achieve a smooth look ie frame to frame transitions. If you are
interested in extreme blurs in your images than you may choose to shoot
at 24 f/ps or explore a more fast shutter speed such as 1/400th as
mentioned above.
