I h ave an Oly E-20N and a Sunpak 455 flash. Does anyone know the
best way to set the flash and camera for correct exposure. Since
the flash is not dedicated I can’t figure it out. There has to be
a better way then trial and error?
Thank a lot…
It looks like the 455 is not on Sunpak/Tocad's current lineup, so presumably you don't have a manual for the flash.
To amplify on what Barry Steward said, most flashes have a switch for 'auto' or 'manual' modes. A flash in 'auto' mode uses a sensor to determine when there is enough light, and stops the light when the flash thinks there is enough exposure. In manual modes, a predermined amount of light is emitted, and their is a guide number for the amount of light.
Typically in the 'auto' mode there are a few different choices (usually color coded), and there is a dial for the ISO. Set the ISO on your camera and flash to the same value. Choose one of the auto power levels, and the wheel or slider will indicate an aperture (f/stop) to use. Using a larger aperture (smaller f/stop number) increases the distance that the flash will reach, but you obviously have less depth of field. Set your camera to manual mode, and use that aperture. Set the speed to an appropriate value, based on how much light you want to come from the background (slower shutter speed means more light from the background will be used, but it might be a different color temperture than the flash, faster shutter speed means more light will come just from the flash, which means things in the background might not be illuminated -- I don't think you have to worry about a max. shutter speed for flash on the E20N). If you are bouncing the light, you might need to adjust the f/stop up/down to get a better exposure.
In manual mode of the flash, you pick a power level (full power, 1/16, etc.) and there should be a guide number for the flash for a given ISO. Divide the guide number by the distance to the subject to get the aperture. Use the camera in manual mode, setting the aperture from the calculation you just made, and the speed as determined in auto mode.
I believe the flash has a setting on the head for different fields of view, you need to adjust this depending on whether you are shooting telephoto or not, and that changes the power level of the flash.
