Manual Exposure Mode (M) - Applicable to both film and digital SLR cameras

This is where the photographer selects both the shutter speed and aperture.

This diagram is mapped, click on a section for more information - the small diagram on the left will take you to the main exposure map

Overview

Viewfinder info of Canon 5DII

Viewfinder info of Canon 5DII - 1/3 stop settings

Dial Location - Aperture - Shutter To take photographs in Manual Mode, you need access to two controls. Aperture and Shutter. There is one dial which rotates and controls the aperture setting - and another dial rotates and controls the aperture. Various camera makes and models have these located in different places and configured in slightly different ways. Because these dials are also used for other settings they are sometime called main and sub control dial. On some cameras there is only one dial and you hold a button down to alternate between aperture and shutter. Check your camera manual for their location.

rotate left for a longer exposure - say 1/60 1/30sec rotate right for a faster exposure - say 1/60 1/125sec   1 investigation using the aperture & shutter control dials

rotate left to open the aperture or set it on a wider f stop - say f8 to f 5.6 rotate right to close or stop down the aperture or set it on a smaller f stop - say f8 to f11 Aperture chart

Viewing the settings

Usually there are two place to view the aperture and shutter settings.

One is a window on the top of the camera, which allows the photographer to view the exposure in difficult situations where they can not see through the viewfinder. On the top of the camera is a window with information about the two components that relate to exposure - the shutter speed or time value TV. In this situation it is on right reading 60. The 60 actually stands for 1/60 second. Because this setting can easily be confused with seconds to denote that the shutter speed is in full seconds there is usually another punctuation beside it. The other figure F3.8 relates to the opening that lets the light in - the aperture. As the dials are rotated the related aperture or shutter numbers alters.   2   investigation using the top data display
Fractions of seconds & full seconds Because this setting can easily be confused with seconds to denote that the shutter speed is in full seconds there is usually another punctuation beside it, in this case a 30". So keep an eye out for this as you set the shutter speed. 3   investigation fractions or whole seconds
Dim light illumination In dim light this window is often automatically illuminated.
The other location is inside the viewfinder - it is usually located below the scene on the screen., which allows the photographer to see the settings as they are framing the subject. Below a scene, viewed through the viewfinder, are a series of numbers and symbols. Again different camera manufactures use slightly different ways of presenting this information, but generally this looks typically like the diagram on the right.
The 0 and longer vertical line in the centre indicates a central position where the exposure is correct. The scale on the left and right of this central position is denoted in what are called one stop intervals - in this case 1,2 & 3 stops.
If the exposure is too great the indicators will light up on the left of this central position - hence the + symbol. Often the indicators light up in 1/2 or even 1/3 stop intervals. In this case the images would be 2 1/2 stops over exposed and we would need to rotate the dial to centre the indicator lights and get the correct exposure.
If the exposure is not enough, the indicators will light up on the right of this - hence the - symbol. In this case 1 stop under exposure
In the case where the exposure is over or under by more than 3 stops all the indicator lights will come on.

On most cameras, the +/- Exposure compensation setting can be used in conjunction. This will often allow up to 2stops over or under exposure.

Understanding the various settings

The aperture is a variable opening that controls the amount of light falling on the sensor

In an SLR, the shutter is most usually a series of two blinds - when the shutter opens - one blind moves across the opening letting light onto the sensor it is then followed by the other sensor. The time differential or physical distance between the binds determine the shutter speed. With a fast shutter speed like 2/000 sec, there is only a narrow slit between the blinds and the slit of light actually moves across the sensor. .However in much longer shutter speeds of say 1sec - the first blind has completed its movement - there is a time gap when the sensor is entirely exposed and then the second blind moves a cross and closes the frame opening.

In some cameras the blinds move vertically.

Together the aperture an shutter con troll the AMOUNT OF LIGHT that reaches the sensor.

So it is possible to have a long or slow shutter speed with a narrow, small or stopped down aperture - or a fast shutter speed with a wide aperture and still have exactly the same amount of light fall on the sensor.

However, while the amount of light reaching the sensor is the same, fast and slow shutter speeds have an effect on moving subjects, camera shake and blur - check out shutter

and wide and narrow apertures have an effect on the depth of field or amount of apparent sharp focus in an image. Check out aperture

Investigations and experiments

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