• Introduction to Exposure - P7

• Setting the Shutter speed and Aperture.

* All elements of exposure work together. *

Shooting modes in the Creative Zone. (we take control of our camera)

• Setting the shutter speed and aperture.
• This is for a Canon 350D (Rebel XT) however the same principals apply to other cameras.
• .
• Some things we need to consider
• (1) If hand holding the camera. What is the slowest shutter speed we can use to stop camera shake?
• ......... a guideline is that 1/focal length of the lens (in 35mm terms) = the shutter speed.
• ......... eg. On a Canon 400D (Rebel) the sensor is smaller than a film (35mm) sensor
• ......... so you multiply the lens focal length by 1.6 to get the 35 mm equivalent.
• ......... With the Canon 17mm-55mm Kit lens equates to a ~28mm - ~ 88 mm
• ........ At 17 mm, 1/30 second would be the lowest shutter speed I would use hand held.
• ........ At 55 mm I would not shoot below 1/100 second.
• ........ for the Canon 75-300mm lens (120mm- 480mm equivalent) I would shoot between 1/120 and 1/500 of a second.
• .
• ....... Below is an example. I am hand holding a Canon 75-300 mm lens @ 300mm (480mm equivalent)
• ....... A larger pic is available by clicking on the picture.

• Canon 350D (Rebel XT) with 75-300 Lens @ 300 (~480).
• ISO 800, 1/500 @ F6.3, hand held.
• ISO 800 has been selected to allow me to shoot at 1/500 second.
• 1/500 second shutter speed allowed me to hand hold the camera .
• The F6.3 has given the added bonus of a beautiful out of focus background because of the shallow depth of field.
• Larger pic is here

• (2) What sort of depth of field do I want? ie: Do I want all of the picture, from front to back, to be in focus?
• ....... The above pic is a good example of shallow depth of field . It has removed a very distracting background.
• ...... . In the picture below I have chosen F22 for my aperture to ensure both the foreground flowers and the background building are both in focus
• ....... A larger pic is available by clicking on the picture.

• Canon 350D (Rebel XT) with 17-85 IS Lens @ 22mm (~35mm).
• ISO 400, 1/10 @ F22 hand held.
• I have selected ISO 400 as it is late in the afternoon and cloudy..
• 1/10 second shutter speed allowed me to hand hold the camera because I was using an image stabilized lens.
• At a focal length of ~ 35mm, minimum hand holding speed would be normally be 1/40 second.
• The aperture of F22 gave me great depth of field so that both the building and flowers were sharp.
• This pic is pushing the limits of hand held photography.
• Larger pic is here

• (3) Do you want to "freeze" the action. Using a higher shutter speed stops subject motion blur
• ........ The shutter speed needed depends on the action and how far away you are from it.
• ........ The London Girls pic (back on page 2) shows a subject doesn't have to be moving fast to show motion blur.
• ........ Sometimes you may want to show a sense of motion, and sometimes you don't, it depends on what you want from the photo.
• ........ The following pic shows the result of having a too slow shutter speed to stop all the motion.

• Canon 350D (Rebel XT) with Canon 70-300 IS lens @ 140mm (~224mm)
• ISO 400 1/200 @ F8 .Hand held + fill in flash.
• The shutter speed is fast enough to ensure the birds bodies are sharp but not sharp enough the freeze the motion completely of the fluttering wings.
• Taking control of my camera has also allowed me use a fill in flash (the subject of another tutorial).
• Larger pic is here.

• Mostly lighting conditions will not allow a high shutter speed to stop fast action and also a small aperture for great depth of field.
• .
• How do we set the shutter speed and Aperture?
• On a digital Canon Rebel adjust the mode dial so it is in "the creative zone"
• ie: P or Tv or Av or M or A-DEP
• P (Program) Mode - This is a fully automatic mode, however you can shift the aperture/speed combination
• .... Press the shutter button halfway down and then turn the main dial (just behind the shutter button) to shift the aperture/speed combination.
• ..... The dial remains active for 6 seconds.
• ..... I use this for "snapshots". I can change the exposure settings to what I want with a minimum of fuss.
• .
• Tv (Shutter priority) Mode.
• ..... Here you can set the shutter speed by turning the main dial. When the shutter button is pressed halfway the ca mara will automatically set the aperture.
• ..... I tend to use this when
• ............(A) Using a long telephoto lens UI will set it to the minimum hand holding shutter speed (as per above).
• ............(B) If shooting action eg I will set it to a shutter speed to "freeze" action, if that is what I want.
• .
• Av (Aperture Priority mode)
• .......... Here you can set the aperture by turning the main dial. When the shutter button is pressed halfway the camera will automatically set the shutter speed.
• ..... I tend to use when shooting landscapes ( I will select smaller apertures [ F16-F22 etc] for greater depth of field) or portraits where I will want to have distracting backgrounds out of focus (so I will set a wide aperture [F4 to F5.6 etc]).
• .
• A-DEP - (Automatic depth if field) It is similar to P mode however the camera will attempt to set the depth of field , via the aperture, by looking at what is in focus and what is not in focus.
• ......... I have never used it......
• M for Manual exposure - Here you can both the aperture an shutter speed to almost anything you like. The camera does not attempt to adjust the aperture or shutter speed.
• ............ When taking very long exposures at night. The shutter speed is set to "bulb" and the shutter will stay open as long as you have the button pressed.... ( Another tutorial?)
• ............Or when I feel the camera's metering system is being fooled by the lighting conditions. (yet another tutorial).
• ............ Here is an example. The dark trees at the bottom of the sky would have influenced the cameras exposure meter resulting in an overexposed sky. I took a meter reading from just the sky (in Tv mode) and made note of the camera recommendations. I then switched to (M) Manual mode and dialed in a shutter speed and aperture to give me the effect I wanted.
• ..... A larger pic is available by clicking on the picture.

• Canon 350D (Rebel XT) with Canon 70-300 IS lens @ 70mm (~105mm)
• ISO 200 1/100 @ F6.3 .Hand held.
• The shutter speed is fast enough to ensure the trees are sharp. It wasn't windy.
• The ISO of 200 was set to minimize noise and still be able to take the picture at 1/100 (I was using an image stabilized lens).
• I used manual exposure to allow the sky to be seen the way it was.
• If the camera would have set the exposure the dark trees at the bottom would have resulted in a lot lighter sky.
• The exposure metering system is not infallible.
• Another tutorial coming up for exposures in difficult lighting conditions?
• Larger pic.

Remember - Rule # 1 - Read the book! - the one that came with your camera.