NJ Photographers - Re-think the Exposure Triangle with this Cheat Sheet
One of the first things you start learning when it comes to beginner photographers is the exposure triangle. The exposure triangle is the relationship between:
Shutter Speed / TV = Time Value which is the movement in the image.
Aperture / AV = The depth of field or DOF of the image
ISO = The sensitivity of the camera to the given scenes light sources.
The exposure triangle is called such because as you make an adjustment to one of these three, you in turn should make an adjustment to one of the other two if not both settings to accomodate for the change in the amount of you let you establish to enter the cameras sensor.
We feel that TV or Time Value, otherwise known as your Shutter Speed is the first aspect of the image you should consider as that is the part that most easily make your photos less than ideal. The movement of whats going on in any given moment should always be factored into the final image.
Do you want to show the motion but freeze some of the action (such as a racecar, or athlete)? Do you want to have the movement blurred while the rest of the image is in focus (such as waterfalls)? Do you want to have a mixture of both such as can be accomplished with Rear Curtain Sync? All of these aspects of movement can effect how you approach to photograph a scene.
It is always best to set your Shutter Speed / TV initially to the same speed as your focal range. So lets say you are shooting with your brand new 24-70mm Canon L series lens. Lets say you set it to shoot at the 24mm range. You would set your TV to 1/25 at minimum to not risk unintentional motion blur.
So what happens when you want to zoom in and go to 70mm? While it doesn’t effect your DOF in and of itself, you risk motion blur by shooting at 1/24. It is best to go to 1/70 TV. BUT AT 1/70 TV, you are then taking a faster photo, which means less light.
In turn you should adjust your AV and ISO to compensate for the loss of light. These constant slight adjustments are way its better to approach the concept of the Exposure Triangle to the one shown here, rather than a standard triangle.