blancing hotshoe flash / strobe with weak/dark Fluorescent

[etan_lightstone]

A similar question to the balancing with Ambient light below.. but a

bit more extreme.

 

I have two vivitar flashes (285hv) which work wonderfully through

umbrellas to create close portraits with a nice background etc.. I

fire them remotely obviously.

 

In this case I'd like to create a moody portrait in a dark garage area

with dim fluorescent lights in the background. Obviously even the

weekest setting of the flash (probably iso100 f5.6) through the

umbrella would mean a 1 or 2 second exposure to let the background

expose properly.

 

My problem is.. when I have tried this in the past.. I get a horrible

effect of blur after the initial flash burst as the ambient light

starts to light the subject which isn't absolutely still.

 

If I boost the setting.. I could have the flash powerful enough to

require my camera to be f16 iso100, and for the remaining 15secs of

exposure have my subject run out of the scene.. but then the walls

behind her start to overlap with the initial exposure of her... so

this doesn't work at all.

 

BTW I have a 300D, so no rear curtain sync. Even if I did rear

curtain.. she still would have a wierd blur coming from the other

direction (assuming she moves slightly during the 1 or 2 sec shutter

in my inital scenario).

 

How do people normally do this?

 

P.S. I'll whitebalance for the flash, I don't care that the hue of the

ambient is funky.

[brooks short]

Normally you would pose the model and have her stay still while you use a long shutter speed to burn in the bkgd fluorescent lights.

 

I've done shots like this many times for corporate/industrial slide shows and using 100ISO trans film and shutter speeds of 1-6 seconds.

[etan_lightstone]

Where you using a flash as well? or just ambient light?

 

After the initial blast of flash.. the ambient light over the next 6 seconds would essentially being to overlap the lighting on the model. Overexpose maybe?

 

I suppose it would work if the model was posed in a shaded area with respect to the ambient light.. and the flash just illuminates the model for a second... the rest of the shutter time is spent exposing the background with the model being very still

[etan_lightstone]

Well I tried it, and even having the model hold very steady during the full 1 second exposure resulted in some lack of sharpness as the ambient light starts to illuminate the subject that was already blasted with the flash.

 

hrmmmm ?

[michael_madio]

You want to minimize the shutter speed, so you need to increase the ISO and/or aperture.

 

If using flash and you want to register a bit of the ambient light, a.k.a "dragging the shutter", use a high ISO, large aperture, and adjust the shutter so the ambient is under-exposed by 1.5-2 f-stops.

 

If you want something more "moody", use ambient light only. Again, use high ISO and large aperture to minimize the shutter speed. Converting to B&W might add to the look you are trying to achieve.