Basic Camera Operation

Understanding Exposure

Three things control exposure
• Shutter speed 
• Aperture
• ISO (ASA) is the “film” speed
Reciprocity - In photography, reciprocity is the inverse relationship between Shutter Speed, Aperture, and ISO


Shutter Speed (how long the shutter is open)
Varies from camera to camera
30 sec. to 1/8000 sec.
Choice of shutter speed is usually determined by the speed of movement within the scene
Can be used to stop the action (fast shutter speed)
Can be used to create motion effects (slow shutter speed)




1/30 Second
ISO 400

1/125 Second
ISO 400

1/500 Second
ISO 400

Shutter Speed 




Slow (Long Duration)
Motion Blur & Camera Shake



Fast (Short Duration)
Movement is Frozen

B 30s 15s 8s 4s 2s 1s 1/2 1/4 1/8 1/15 1/30 1/60 1/125 1/250 1/500 1/1000 1/2000 1/4000 1/8000


Aperture is the opening in the lens
Varies from lens to lens
Measured in f-stops
Small f-stop = large opening
Large f-stop = small opening
Aperture size determines depth of field



1/30 Second
ISO 100 

1 Second
ISO 100 





Large (Wide Open)
Minimal Depth of Field



Small (Stopped Down)
Maximum Depth of Field

f1.0   f1.4   f2.0   f2.8   f4.0   f5.6   f8.0   f11   f16   f22   f32   f45   f64



aperture graphicaperture graphic


Depth of Field
How much of the image (from front to back) will be in focus
Determined by Aperture
Small aperture = greater depth of field
Large aperture = narrow depth of field
F22 (smallest opening) = greatest depth of field
F2.8 (largest opening) = narrowest depth of field
Depth of field is used in controlling “selective focus”
Depth of field is affected by the distance from the lens



Range varies from camera to camera
Choice of ISO is determined by scene lighting or speed of action
Increasing ISO adds noise to the image
Use the slowest (lowest number) ISO whenever possible





Least Sensitive
Least Noise



Most Sensitive
Most Noise

25    50    100    200    400    800    1600    3200    6400    12800


Reciprocity is used to explain the F/stop to Shutter Speed to ISO relationship. f16 at 1/125sec 100 ISO is the same as f11 at 1/250sec 100 ISO is the same as f8 at 1/500sec 100 ISO...

It's the total AMOUNT of light that counts
The interaction between the Aperture and the Shutter Speed determines the volume of light hitting the film. The aperture and shutter speed settings go in "opposite" directions. If you have a tiny opening, you need to have the shutter open a very long time to allow enough light in to properly expose the shot. Conversely, if you have a large opening, you need the shutter open for a short time to let in the right amount of light in to properly expose the shot.

Compare this to a faucet. If you have the valve opened only slightly (a tiny aperture), the faucet needs to run for a long time (shutter speed) to fill the sink. And if the valve is opened all the way (large, or wide-open aperture), the faucet needs to run for far less time in order to fill the sink.


Aperture, Shutter Speed, ISO Reference
So now that you have a better understanding of aperture, shutter speed and ISO how about some real world reference.

Shutter Speed

  • Slow shutter speeds less than 1/60 second can cause camera shake and blurry images; use a faster speed, an IS (Image Stabilized) lens, or a tripod.

  • To exagurate motion, use shutter speedless than 1/30 of a second.

  • Use fast shutter speed (e.g. 1/1000 sec or greater) to freeze motion.

  • Possibly use a slow shutter speed and a technique called panning to show motion.


Pan BlurPan Blur

Fast Shutter SpeedFast Shutter Speed




  • Large apertures e.g. f2.8, f4.0 are generally used when you want the background (behind your subject) to be out of focus.

  • Small apertures e.g. f11, f16 are best used whenever you want most of your scene to be in sharp focus.

  • Large apertures (e.g. f2.8, f4) are often used for portraits photography and food photography.

  • Small apertures (e.g. f11, f16) are often used to photograph landscapes, and anything that requires a wide area of acceptable focus. 

large dlarge d

large depthlarge depth

Shallow depthShallow depth




  • ISO 100-400 for outdoors

  • ISO 400-1600 for indoors

  • ISO 1600 or greater for when you need to record as much ambient light as possible with a faster shutter speed.

  • At ISO 400 you may begin to see noise.

  • At ISO 3200 you might find the noise to be overwhelming the image.

  • There are no hard rules!

iso noiseiso noise


Bracketing exposure means taking one frame at indicated setting, one frame at 1-stop under-exposed, one frame at 1-stop over-exposed.
Bracketing shutter speed:
1/60, 1/125, 1/250 sec.
Aperture stays the same.
Bracketing aperture:
f5.6, f8, f11
Shutter speed stays the same.



1/125 Second
ISO 200



1/60 Second
ISO 200



1/30 Second
ISO 200

Exposure Adjustment:

Many cameras also have a feature where you can use automatic exposure, but force the camera to shot at varying steps higher or lower than the light meter is reading.  This is Exposure Value Compensation, or EV.  An EV –1 will underexpose the exposure one stop. An EV of 2 will overexpose the exposure two stops.  This can be very handy for quickly compensating for the in camera light meter when it is not giving you the exposure you desire. Find this button on your camera and learn to use it!


Manual focus

• Can be slow and imprecise
• Difficult in low light conditions

Auto focus

Multi-focus: Finds the object with the most contrast near the center of the frame.

Focus 1Focus 1

Focus 2Focus 2

Center focus: Uses the target in the center of the viewfinder. 

Area focus: Allows you to move the target used in Center Focus to other places in the viewfinder.

Review…important terms
• ISO = “film” speed
• Shutter Speed = how long the shutter is open (seconds or fraction of a second)
• Aperture = size of the opening in the lens (large number = small opening, small number = large opening)
• Reciprocity = ISO, aperture and shutter speed
• Depth of Field = how much of the image is in focus (front to back)