D100 rear-curtain and slow flash syncs? Whats the purpose?

Discussion in 'Nikon' started by hunter_harrison, Jun 18, 2005.

  1. Good morning,

    To start, I did a search and read the manual. The search yielded
    vague responses at best. The manual does a good job of describing the
    timing, but does not touch on the purpose or use.

    Regarding slow sync, I understand that the flash fires when the
    shutter first opens. I can guess from the manual that this would be
    good for a long exposure with a moving subject in the foreground. For
    example, you would meter for the night sky and then move your subject
    (lets say a person) into place. When you fire on the long exposure,
    the flash would fire and light the person, but the shutter would stay
    open to capture the appropriate exposure for the night sky. That way,
    any movement by your foreground subject is not captured. Instead,
    they are frozen by the flash. Is this correct? Is there any other use
    for this flash sync setting? I guess I want to know, creatively, what
    I can do with this setting.

    Okay, now rear-curtain. This one I don't think I understand as well.
    I know the flash fires just before the shutter closes. I guess that
    this could be used for a moving foreground subject and a stationary
    or unimportant background. When the shutter opens, the camera would
    capture the movement of the subject and then, right before the close
    of the shutter, fire the flash to freeze there last point in the
    frame. This would light the background and freeze the subject at
    their final location and capture their movement. Again, is this
    correct? What is the creative potential for this sync setting?

    How do you use these settings to get nice creative shots with flash
    work?

    Thanks!
     
  2. Hello, I just bought a camera and some film. Can someone teach me how to use it creatively?

    "Whats the purpose?"

    Hunter, to me it seems as if you understand the settings and purpose very well, the manual explains a lot as well.

    Creativity, is mostly one's uniques vision.

    Let's say you want to photograph a fireplace or an iPod but you want to see the screen lit. Well, you use slow synch. You light the entire setting with the strobes and expose long enough to get the blue light on the screen.
     
  3. Remember that any flash, no matter when within the exposure it fires, will only 'freeze' anything if it is strong enough to light the subject properly. So, in your rear synch explanation, the background might not be lighted if it is too far away. Conversely, any ambient light will only record if it is bright enough. In the attached picture, the dancers were frozen with rear synch flash. I exposed for the stage normally and the flash was not strong enough to reach it. While the foreground dancers were not well lit enough to record on film w/o flash. The pic was made with the on camera flash on the N80. It was a quirky experiment but might serve as an example. -A
    00Cb7U-24220284.jpg
     
  4. I use rear curtain synch when I want ambient light to be the dominant light and light from the flash to be secondary light, like in fill flash used with nature macro photos. You want the image to look very natural--ambient light dominant--no black background. Flash is used to add just a tad of light where needed--the animals eye, feather or body detail or to fill minor shadow areas. At weddings, I use it to light the background as much as possible and to light the bride and groom who are close to the camera. Use your search engine and try finding Moose Peterson flash techniques. Joe Smith
     
  5. One of the classic (or is that cliche) rear sync examples is a car driving through the frame with lights on, at night. If the flash were fired at the beginning of the exposure you'd get an image of the car, then light trails moving forward. The effect would 'seem' as if the car were moving backward. With rear sync you get the light trails, then the car, it looks like it's moving forward!
    Sports photography is another place where I've seen it used creatively for good effect. Think Skateboarding, snowboarding, etc. Timed correctly you get the athlete blurred with a sharp image when the flash goes off ideally at the peak of a stunt.
     
  6. you see a lot of concert photography with rear-sync flash too. Captures some of the sense of motion:
    <p>
    <img src="http://www.daniellesphotogallery.com/photos/s429-p1.jpg">
     
  7. I'd upload an example from a couple of days ago but I haven't gotten the images off of my D70 yet. Here's the idea though. I used rear synch to photograph myself in my living room. I was holding the camera at arms length pointing towards me and slowly moving around in a circle. So the resulting shot has a blurred background lit with ambient light that gives the impression of motion and my face is lit with flash and looks perfectly frozen in the composition. Because the main subject (me) was close to the on-board flash I got a very solid freeze and because the background was dimly lit and exposed for a long time (a 20th of a second or so) it appears bright but streaked with motion. I use rear synch to help crystalize the foreground when shooting action shots in the daytime too, though slow synch would probably work fine in this application too:
    00CbAu-24221684.jpg
     
  8. Here's a picture of my friend juggling glowing balls, in the dark. By using a slow shutter speed and fast lens I was able to get motion trails for the balls. Since I used rear-curtain sync flash, the trails lead up to the point where the motion was stopped, when the flash fired at the end of the exposure. If I'd used front-curtain sync, the flash would go off at the beginning of the exposure, and the trails would seem to lead the way in front of the balls, instead of following them. Using a normal shutter speed and flash, I wouldn't have any trails at all, just a frozen moment.
    00CbZC-24231184.jpg
     
  9. Hey everyone, thanks for the ideas. I guess the settings were as I expected. Furthermore, it is nice to see some good examples of how the sync would effect the picture. I guess I understood the concept, but my own test shots did not yield the results. Comparing normal sync to my test rear sync, I could not see a difference. Now, I know that I was using the sync setting incorrectly.

    I have some great ideas now. Maybe I will do some test shooting this afternoon. Take care everyone.
     
  10. "Let's say you want to photograph a fireplace or an iPod but you want to see the screen lit. Well, you use slow synch. You light the entire setting with the strobes and expose long enough to get the blue light on the screen."
    I can't see how this would work. The strobe would light the screen (presumably off) which will then be recorded as an LCD green (or whatever an ipod screen looks like) the rest of the exposure will show some blue but it will be severely lightened by the green. This sort of shot is best as a double exposure where the strobe shoots the flash with a black card over the screen then remove the black card and double expose the screen in the dark.
     
  11. In the attached picture, the dancers were frozen with rear synch flash. I exposed for the stage normally and the flash was not strong enough to reach it. While the foreground dancers were not well lit enough to record on film w/o flash
    This is also not quite right. True the flash is not strong enough as is obvious by the white t-shirt over the black background. But even if the shot was exposted properly all the bits that were overlapping the background would be too light. Their torsos will be correct because they are over black but their heads would be over exposed unless the dancers stayed motionless after the flash fired.
     

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