Monday, 8 July 2013

Take the Plunge - Get Off Automatic


Take the Plunge – Learn to Use Manual Settings
By manual settings I mean either semi-manual or manual. However, we will not be “writing off” automatic setting. Reasons for using automatic are:
1.    If you new to photography it is best to learn the techniques of photography first, e.g. composition and light. You need to train your photographic eye and you need to be free of fiddling with settings to learn those techniques.
2.    It can save you when you’re not quite sure of what settings to use. So you can shoot using manual settings but then take some in automatic just in case you muffed it. If you are in a big hurry and don’t have time to use manual settings, automatic is the best option.
3.    If the terms Aperture Priority, Shutter Priority, ISO and Manual mean nothing to you, then use automatic. There is no pressure in using automatic but when you want to try manual settings, don’t choose your grandson’s first birthday, practice around your house first.
4.    When your subject won’t sit still, automatic is the best option. When kids are running in and out of different light situations it is difficult to keep adjusting manual settings.
People never say, ‘That’s a great shot, did you use automatic?’ However, over time you’ll be happy with images where you have been the boss of the camera.

Let’s Take the Plunge


The Settings
On the Canon EOS the settings are P, Av, Tv, M, A-Dep.
“P” means automatic exposure (AE). It sets the exposure (aperture and shutter speed) automatically. However, you have control over:
§  ISO-the sensitivity of the sensor 

§  Automatic Focus -AE

§  Automatic Focus Points 

§  Continuous Shooting or burst 

§  White Balance – WB 

§  Exposure Compensation


§  Flash – Is not automatic
§  Automatic and Manual Focus  AF – M
§  Picture Style (Standard, Portrait, Landscape, ) 

§  Metering Mode (Measuring Brightness)

§  Image Quality (Pixels, RAW)

“M” means entirely manual where you choose all settings separately.
“A-Dep” means automatic DOF, everything will be in focus.

However today I would like to concentrate on Av (Aperture), Tv (Shutter Speed) and ISO (Sensor Sensitivity) settings and how they affect exposure.

All these elements relate to light and how it interacts with the camera. Briefly:
ISO
Is the measure of the sensor’s sensitivity to light. (changes graininess)
APERTURE
Is the size of the opening in the lens (changes DOF)
SHUTTER SPEED
Is the amount of time the shutter is open (shows motion)

It is the intersection of these elements that gives exposure in other words exposure is the amount of light (aperture) that is recorded over a specific time (shutter speed) on the sensor (ISO). A change in one element will impact on the others, so always keep them in the back of your mind.

1. Aperture or f/stop

Basically it is a hole that opens and closes to let light in. A high f/stop number means less light and a low f/stop number the more light is recorded on the sensor.

The f/stop numbers look like this <- 2.8, 4, 5.6, 8, 11, 16, 22 ->.

Aperture controls the Depth Of Field (DOF). The DOF is the amount of the image in focus. With a deep / long DOF everything is in focus and a shallow / short DOF only one segment is in focus, the rest is blurred.

For landscapes use a small aperture (large number) that will give you a deep DOF. For portraits use a large aperture (small number) that will give you a shallow DOF so that the face is in focus and the background is blurred. For macro use a small aperture for a shallow DOF.

 Use a shallow Depth of Field to focus on a particular subject. Use a small number f/2.8 -f/5.6


Very large aperture eg f/2.8

large aperture eg f /5.6

small aperture large number eg f/22


Your challenge:
Set your camera on Aperture Priority (Av / Ap / A). It will automatically set the shutter speed.

Place 2 objects 10cm – 1m apart outside or in a well-lit room. Set the lens on the lowest possible Av number e.g. 2.8 - 4.0 by rolling the wheel and looking through the viewfinder or on the LCD screen. Now focus on the object closest to you and shoot. Then roll the wheel up to the next number and shoot again. Continue decreasing the aperture taking a shot at each setting. Check the results.

2. Shutter Speed (Tv setting)

It’s the moment when light is exposed / recorded on the sensor or another way of saying it, its the amount of time the shutter stays open when you hit the button.
The settings are in fractions of a second and look like this:
<- 1s, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/250, 1/500, 1/1000 -> The higher the denominator the faster the speed.
Sutter speed controls motion in a photograph. The longer the shutter is open the more motion it will record, (blurred effect).
The shorter the time the shutter is open the more the motion will freeze.
Aperture and Shutterspeed work together. A fast speed needs wide aperture. The camera will do this automatically unless on Manual Setting, (M).
You need to hold the camera very still with slow shutter speeds or else you will get ‘camera shake’ blurry shots. It Is best to use a tripod with slower speeds than 1/60. A general rule is to match the speed with the length of the lens. E.g. 250mm lens you would use 1/250 shutter speed.
Effect of shutter speed on light


left= automatic setting,   right=shutter speed setting

fast shutter speed freezes the ac

slow shutter speed blurs the action

Your challenge:
Set your camera on Shutter Speed (Tv). Roll the wheel to change the speed.
Shoot 2 moving objects (of the same type). Your goal is to freeze the movement in one (use fast speed e.g. 1/1000 and show movement ie. Blur the movement in the other (use slow speed). The trick is to keep the rest of the image sharp.

3. ISO

ISO changes the graininess (noise) of an image or another way of saying it is that it measures the sensitivity of the sensor.
The lower the number the lower the sensitivity and the less grain (sharper). The higher the number the more sensitivity and the more grain but it is used in low light situations.
If you change ISO it will impact on Aperture and Shutter Speed. It allows you to use a faster shutter speed or a smaller aperture (ISO 800) or a slower shutter speed and a wider aperture. (ISO 100)
When choosing ISO settings think – light, grain, tripod, moving object.
If there is plenty of light and you want a sharp image with little grain or if you use a tripod or the subject is stationary or you need a shallow DOF, use a low ISO number (100 – 400)
If it is dark or if you want a grainy effect or if you don’t have a tripod or if the subject is moving, use a high ISO number (400 – 800). This allows you to use a faster shutter speed and a wider aperture for good exposure, but will be noisy. It is good for indoor sport.

Your challenge:
First find the ISO button. Press the button while in any of these settings P, Av, Tv, M, then scroll up or down the ISO numbers. Take indoor, low light shots with high ISO. Take outdoor, high light shots with low ISO.