If I kill the ambient light.....?

[RobNZ]

Had a 2nd shoot for a friend the other evening which basically required getting a shot of her border collie exiting a tunnel thats used in agility training. This shot is to complete a triptych.

Shoot time was scheduled for 7pm (around 90 minutes before sunset) ended up being heavily overcast so the natural light level was very low which I thought would be good and I could easily kill the ambient light and use 2 strobes to light my fast moving subject, but man did I have issues.

I couldnt get rid of motion blur on the dog and this had me scratching my head, in hindsight I have gone back through them and realised that I hadnt completely killed the ambient because on this screen I can see the background, on the camera's lcd at the time the scene appeared mostly black and histogram seemed to indicate this also. Note to self, if it looks dark enough, go one stop further, lol.

So my intention at the time: kill the ambient light, use the strobes to light my subject and freeze him in place (did not want any motion blur, defaults to first curtain when using wireless triggers).

SOLVED: There was still enough ambient light to slighlty expose the lighter parts of the dogs coat which gave me the motion blur (@ 1/200th) with the strobes firing on first curtain?

Whilst there I also put one of the strobes on my hotshoe, set it up for rear curtain, set the other strobe to S1 (optically triggered on first light source, hot shoe strobe set to manual, no TTL) and that did improve the situation.

Anyone disagree with my theory or have any other advice?

My friend is happy with the shot I presented her which is great, but its not something I would print.

 

[Big Mike]

As long as you are OK with how the photo will look, after you have killed the ambient, then that sounds like a good solution.

For reference (for those who may not know), each flash photo is actually two separate exposures....the flash exposure and the ambient exposure. Usually they line up nicely and/or one overpowers the other, so we just see one 'normal looking' image, but they are both there.

This becomes troublesome at certain light levels because it's dark enough that we need to use flash, but still bright enough that the ambient light will cause blur in the ambient exposure. In this case, you can do whatever you can, to increase the shutter speed (higher ISO) and embrace the ambient exposure....or you can go the other want and try to kill the ambient exposure by using a low ISO, fast shutter speed and/or smaller aperture. Keep in mind that the lower ISO and smaller aperture will require more power from the flash.

So the key is really to control your shutter speed because it doesn't affect the flash exposure....except that you need to keep the shutter speed below the camera's max sync speed.

 

[Robin Usagani]

Lets see the shot! It is always tricky when you still have some ambient light. Personally I would have kept the flash on my camera and do 2nd curtain. I think it is cool to see the motion trail from the dog. I probably keep the camera to manual focus on a tripod and really time my shot to make sure the dog is in the frame when the flash fires.

 

[RobNZ]

Cheers for the responses. Thats the other issue I was dealing with Big Mike, is how it looked with all ambient removed outdoors, pretty dark where there is no light return.

The shot for Schwetty.