Frequently Asked Questions - GigaPan EPIC PRO V User Manual

4.3 Frequently Asked Questions

1. What changes exposure and why should I only vary the shutter speed?
When you capture multiple exposure brackets for each position for the purpose
of capturing HDR images, you vary the exposure by varying the shutter speed
and keeping the ISO & aperture constant. Do not vary the aperture as this will
change the depth of field.
2. What does EV (Exposure Value) mean?
An increase of one full exposure value means that you double the amount of
light in the image. You can do this by doubling the shutter speed from one
second, to two seconds. A decrease of one full exposure value means that you
decrease the amount of light in the image by one half. One full exposure value
less than one second is one half-second.
Exposure -2
Value
Shutter 1/4 s
Speed
Canon 4
Cameras
Nikon 4
Cameras
3. What is a simple method to determining the center exposure, number of brackets,
and the exposure value separation?
Use an evaluative metering mode to determine the center "Time/Exposure"
and then simply choose three brackets with a larger EV separation, such as
1.7 EV or 2.0 EV.
4. What is an accurate method of determining the number of brackets and the
exposure value separation?
Determine the exposure for the brightest, average, and darkest areas that you
would like to be able to see details in your image.
Use the following steps...
1. Change the metering mode to spot mode, if your camera has that capability.
2. Point the camera lens to each area and depress the shutter button half-way
to determine the shutter speed that will center the reflective meter marker
to zero. Take note of the shutter speeds as you do this.
3. Determine the distance from the average exposure which you use to set
"Time/Exposure". Do this by counting how many shutter speed settings your
darkest and brightest shutter speeds are away from your "Time/Exposure"
setting.
4. The default setting for shutter speeds in DSLR cameras is 1/3 stop. When you
change the shutter speed three times, you changed the exposure by one
exposure value or one EV.
-1 0
1/2 s 1 s
0"5 1"
2 1"
+1 +2
2 s 4 s
2" 4"
2" 4"
33