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This is my second attempt today. First attempt was in the day and with the long shutter speed it over-exposed most of the shots. So second attempt was at night.

Results of the second attempt. I am hoping somebody can shed some light on what I am doing wrong. Is it not enough power being fed through the flashes?

This is sort of an out-take of what the environment was.

F7.1 8sec ISO200


This is the result, not completely happy as subject isn't sharp. The turn-thing was spinning pretty fast, but I had an impression on second curtain sync, I would be able to get it sharp, but I tried and I tried. NO success. Somebody, advise please!

F7.1 6 seconds ISO200. 2 x SB600 in M mode fired at 1/2 triggered via CLS.


THanks..

I like the second one.

the key is the balance between how ambient light you captured during the long exposure compare to how much light is provided by the flash.

if you let in too much ambient light during the long exposure, you've already recorded a very visible but blurry main subject, the flash at second curtain won't make that blurry image disappear.

so if you want the main subject sharp, you'll have to underexpose the ambient during the long exposure. That way, only the flash is used to capture the main subject and it'll be very sharp. But the problem is, you don't capture too much background movement and the image will look very static compare to the first shot.

so if you really want the main subject to be sharp and you want to capture the sense of speed/movement, what you'll need to do is selectively underexpose the main subject. I can think of two ways to do that.

1. light up the background and everything but the main subject with some constant light source (or flash strobing at high frequency). so during the long exposure, you captured all the movement from the background but the main subject is still underexposed and just barely visible. Then the rear curtain flash is used to light up the main subject and make it sharp sharp.

2. the other way is to use a "black card". For example, if you are using a 2 second exposure time, use a black card to cover up where the main subject during the first 1-1.5 second. Then just before the flash fire at rear curtain, remove the black card so you'll record a sharp image of the subject. But this technique requires a bit of practice as you'll need to get the timing just right and also you need to do it so in the photo you don't really see the transition from the black card to non-black card area.

(09-20-2009 07:45 AM)yellow15 Wrote: [ -> ]the key is the balance between how ambient light you captured during the long exposure compare to how much light is provided by the flash.

if you let in too much ambient light during the long exposure, you've already recorded a very visible but blurry main subject, the flash at second curtain won't make that blurry image disappear.

so if you want the main subject sharp, you'll have to underexpose the ambient during the long exposure. That way, only the flash is used to capture the main subject and it'll be very sharp. But the problem is, you don't capture too much background movement and the image will look very static compare to the first shot.

so if you really want the main subject to be sharp and you want to capture the sense of speed/movement, what you'll need to do is selectively underexpose the main subject. I can think of two ways to do that.

1. light up the background and everything but the main subject with some constant light source (or flash strobing at high frequency). so during the long exposure, you captured all the movement from the background but the main subject is still underexposed and just barely visible. Then the rear curtain flash is used to light up the main subject and make it sharp sharp.

2. the other way is to use a "black card". For example, if you are using a 2 second exposure time, use a black card to cover up where the main subject during the first 1-1.5 second. Then just before the flash fire at rear curtain, remove the black card so you'll record a sharp image of the subject. But this technique requires a bit of practice as you'll need to get the timing just right and also you need to do it so in the photo you don't really see the transition from the black card to non-black card area.

Thanks for the input. I get what you mean about under-exposing.

My only solution is to get a flash to strobe at high frequency. I don't think the SB-600 can do this. Or I get more constant lights. I am in a play ground, so I doubt there is going to be power points for me to use.

Using the black card for a static shot would be ok but this shot as it is was already quite difficult. We got the thing to spin quite fast for at least a complete 1 or 2 rotations per shutter open / close. For the background lights to meet or complete a round (from left to right of frame). Spinning at that speed + the holding the camera and a SB-600 and trying to remove the card and posing would probably all equal a big mess with something getting broken.

I think I just have to accept that, this is the very best I can do. Thanks again though for the insight. I learnt something new!