Digital Single Lens Reflex Camera:What you need to knowISO What does ISO stand for? It stands for International
Standards Organization, which is the group that sets standards for products, machines, systems, etc. (they have a website if youre interested)
When talking digital cameras the ISO is a number that tells you how sensitive your cameras sensor is to light. The sensor, like old fashioned film, is where a photographic image is formed.
To set the ISO push the ISO Button on the top of the Canon Rebel XS camera, then use the arrows on the back of the camera to move the selection of ISO numbers on the LCD screen to the ISO number wanted.
ISO number choices on our Canon Rebel XS are as follows:
You might think of ISO this way:When you have sun screen on your skin, your skin is less sensitive to light. It will take longer for your skin to darken, but the tan will be high quality.
When you do not have sun screen on your skin, your skin is much more sensitive to light. You will get darker faster, but you the tan will not be as high quality.
A u t o I S O 1 0 0 2 0 0 4 0 0 8 0 0 1 6 0 0
Lower/Slower ISOs mean longer exposures and/or bigger aperture openings because they require more light. However, they give you a less noisy and higher quality image.
ISO 100Shutter Speed 1/15th of a secondF 4
Higher/Faster ISOs mean faster exposures and/or smaller aperture openings because they require less light. However, they give you a more noisy and lower quality image.
ISO 1600Shutter Speed 1/125th of a secondF 4
Higher ISO Numbers are good in low light and when
printing smaller, 8 x 10 or less
Lower ISO Numbers are good in bright light and when image will be enlarged to 11 x 14 or bigger
These images are extreme magnifications to show digital noise. Extreme magnification results in image blurriness.
In Auto ISO the camera chooses what it thinks is an appropriate ISO for the lighting conditions
The Shutter and Shutter Speed A shutter is, in essence, a door that when opened, allows light to come into the camera to
expose the digital sensor. The shutter speed controls how long the door stays open to let light into the camera Fast shutter speeds stop action and let less light into the camera Slow shutter speeds blur action and let more light into the camera At higher ISOs it is more likely that you can get a good exposure at a fast shutter speed To change the shutter speed turn the dial between the ISO button and the shutter release
button. When you turn the dial, the shutter speed number on the LCD screen will change (see next page for LCD Screen Illustration)
The Shutter Speeds on the Canon Rebel XS are as follows from the slowest to the fastest: ( = second(s))BULB (keeps shutter open as long as you have your finger on the shutter release button Slowest --30 25 20 15 13 10 8 6 5 4 3.2 2.5 2 1.6 1.3 1 .8 .6 .5 .4 .3 1/4 1/5 1/6 1/8 1/10 1/13 1/15 1/20 1/25 1/30 1/40 1/50 1/60 1/80 1/1001/125 1/160 1/200 1/250 1/32 1/400 1/500 1/640 1/800 1/1000 1/1250 1/1600 1/2000 1/2500 1/3200 1/4000--Fastest
The Aperture and F-Stop An aperture is a perfectly round hole in the camera
lens that refracts light to form a photographic image on the digital image sensor
The size of the aperture controls the amount of light hitting the sensor
larger aperture openings let more light in and produce images with shallow depth of field
smaller apertures let less light in and produce shallower depth of field
F-Stops are the numbers that correspond to the size of the aperture
To change the F-Stop you must hold the AV button down while turning the dial between the ISO button and the shutter release button
The larger the F-Stop number the smaller the hole
The F-Stops on the Canon Rebel XS 18-55mm zoom lens are as Follows starting with the smallest aperture hole: smallest apertureF36 F32 F29 F25 F22 F20 F18 F16 F14 F13 F11 F10 F9 F8 F7.1 F6.3 F5.6 largest apertureThe following F-Stops are only available when the lens
is zoomed out to its 55mm position: F5 F4.5 F4 F3.5
The Light Meter The reflective light meter in DSLR cameras measures the intensity of
the light reflecting off the subject. It helps the photographer figure out which F-Stop and Shutter Speed
Combinations will yield a good exposure. The meter for the Canon Rebel XS is only accessible in what Canon
calls the Creative Modes The creative modes include:M--Full Manual, AV-- Aperture Priority ( You choose the Aperture, the camera chooses the shutter speed), TV--Shutter Priority (you choose the shutter speed, the camera chooses the F-Stop or Aperture Setting) and P--Program Mode (You can choose the F-Stop, the camera chooses the shutter speed. We will use M--Full Manual Mode.
The is activated by tapping on the shutter release button.
The light meter is a scale that tells you if the settings will be under, over or good exposure: -2, -1, 0, +1, +2
When the bar lines up with 0 you have a good exposure. If the bar lines up with -2 or -1 your image will be under exposed or dark. If the bar lines up with +1 or +2 the image will be over exposed or too bright.
One way of using the meter is to choose a shutter speed first. Use the dial between the shutter release button and the ISO button to change the shutter speed.
If you are hand holding the camera, you must choose a shutter speed above 1/30th of a second or higher.
Next, tap on the shutter release button to activate the meter. When the meter is activated, a small bar will appear directly below the meter.
Next press the AV button on the back of the camera and turn the same dial that you did to change the shutter speed. Turn the dial until the bar beneath the light meter is lined up with the 0. Keep in mind that the smaller the F-Stop number, the larger the aperture hole, so smaller numbers mean more light into the camera. The lager the F-Stop number the smaller the aperture hole, so larger numbers mean less light into the camera.
You will see the light meter, shutter speed and F-Stop in the view finder as well as on the LCD screen. Looking at all these settings in the view finder will help you shoot faster.
Shutter Speed F-Stop
Light Meter ModesThe Canon Rebel XS has three light meter modes. Spot metering is not available on the Canon Rebel XS
Evaluative Mode--Is a good all around metering mode and the default mode on the camera. The camera divides the image into 35 zones and reads the exposure for each zone separately. Metering is concentrated on the active Auto Focus Point, even if it is off center. Tries to compensate for back lighting. Evaluative Metering is good for : Tricky lighting general picture taking portraits backlit subjects
Center Weighted Metering--Weighted at the center and then averaged for the entire scene. Reads the entire picture area, but is always weighted from the center of the picture, regardless of where the Focus Points are. Does not compensate for back lighting. Center weighted metering is good for evenly lit subjects.
Partial Metering--Is very precise metering that measures only about 9% of the picture, near the center of the screen. Only the part that is measured will be properly exposed. You can use the AE Lock Button(Auto Exposure Lock) when putting the subject off center. This setting is good for: Neon Lights stage performances when the background is much brighter than the subject due to backlighting.
For most of our shooting Evaluative metering is the best and most versatile choice.
White Balance The White Balance (WB)setting on your camera, allows you to adjust your camera to accurately record color in different light sources. Different light sources have a different
color temperature Color temperature is measured on the
Kelvin scale (K) The color temperature of a light source
can make colors appear more cool (blue) or warm (yellow)
Very cool light like that of blue sky, have a higher color temperature
Very warm light, like that of a candle, have a very low color temperature
We dont generally notice this difference in temperature because our eyes adjust automatically for it. So unless the temperature of the light is very extreme a white sheet of paper will generally look white to us. Our digital cameras need to be set for the correct White Balance in order to record color temperature
Yellow Warm Light
Blue Cool Light
For the Science Geeks in each of us: So, why do we measure the hue (color) of the light as a
"temperature"? This was started in the late 1800s, when the British physicist William Kelvin heated a block of carbon. It glowed in the heat, producing a
range of different colors at different temperatures. The black cube first produced a dim red light, increasing to
a brighter yellow as the temperature went up, and eventually produced a bright blue-white glow at the