majin tcz wrote in post #15989212
My flash understanding may be a little off. But with me shooting ETTL just as if the flash is on the top of my camera doesnt the shutter speed just affect ambient light at that point. Isn't the flash supposed to "freeze" the subject?
One thing you always gotta remember in flash photography is that you are always taking TWO PHOTOS simultaneously. TWO. One photo with ambient light, the other photo with flash. Think of the two as completely separate entities and it's easier to execute what you want. Consider what the photo would look like with no flash. In fact, as a learning exercise, first take the photo with NO flash and see what it looks like. If you can see motion blur or camera shake, then you will STILL see it even when you turn the flash on. In order to mask the motion blur and camera shake, you gotta decrease the ambient exposure to a point where you cannot see it. In other words, your subject will be very dark with no details clearly visible. Then when you hit them with flash, it will be the flash that exposes the subject. Because the flash exposure is strong and the ambient exposure is weak, you will get a clear, crisp photo regardless of the shutter speed.
Here are a couple examples.
In this photo, we went into the woods by the reception hall. It was DARK. The only light coming through was a couple of lights on the building that were trickling through. My settings were ISO800 F/2.8 13 SECONDS for a shutter speed. I put the camera on a tripod to avoid camera shake, and set up an off camera light to illuminate the couple. Now remember what I said, if you want a crisp flash photo of your subject, you gotta make sure the ambient exposure on the couple is very low. But the question is, how do you get a background that is bright enough while keeping the subjects really dark? Well, notice I placed the couple directly in the shadow of a large tree trunk. THAT keeps them dark. Then I hit them with the flash and they came out super clear and crisp. It is all about controlling the light. ALL the light, including ambient.
Then for the following photo, I took a different approach. I WANTED the effect of motion blur visible in the photo to create a dynamic feel to the image and interaction. So I set the ambient exposure so that the couple was around 1.3 stops underexposed. That way, the ambient exposure of the couple would still be visible, but still totally overwhelmed by the flash exposure, which was much stronger. This way, the flash exposure still clearly punches through with a crisp exposure, but you can still see all the motion blur on the couple. I panned and shook my camera during the exposure to create even more of a sense of dynamic motion. Settings were ISO100, F/2.8 1/6, shot on a 50L. Yup, shooting after dark at ISO100. But I needed the 1/6 shutter speed in order to create lots of motion blur in the image.
So you see, shooting with flash never guarantees a crisp photo. You are always taking two separate photos and slapping one on top of the other. What *YOU* need to do is control the balance between the two photos in order to get the effect you want. And it can go from totally crisp to totally blurred, and everything in between.
