Slow speed sync flash

[thesooth]

Hey,

I've tried to do slow speed sync flash to achieve blurred background and sharp subject, using 200 ISO film, I set my shutter speed to 15 and closed aperture to 16 to have a properly metered scene, I set flash to weakest power to freeze a motion and after developing photos - came blurry, I mean not only background was blurry but subject too, I also tried to fire flash on a half power and underexposed for 1 stop, but anyway pictures are too blurry.

Could somebody help and point out what I did wrong? Maybe I need to underexpose a lot more like 2-3 stops?

Example of photo:

 

[BrianShaw]

Was the camera on tripod? Looks like camera movement to me.

 

[thesooth]

M6, no tripod here, this is why I'm using flash

 

[koraks]

Try putting the exposure of the ambient on something like -1 stop (underexposed) and set flash exposure at +/-0 stops. This will emphasize the (sharp) flash exposure over the ambient. Experiment with the ratios between both exposures; you may even want to go down to -1.5 or even -2 for the ambient, especially if there's lots of sky in the scene.

 

[BrianShaw]

M6, no tripod here, this is why I'm using flash

At 1/15 second even a flash might not save you from camera movement smearing given the amount of ambient lighting.

 

[ic-racer]

You need a much more powerful flash.

 

[Chan Tran]

You need a much more powerful flash or a much darker scene. The flash exposure for the subject must be a lot higher than the ambient exposure even at a long exposure time.

 

[thesooth]

Try putting the exposure of the ambient on something like -1 stop (underexposed) and set flash exposure at +/-0 stops. This will emphasize the (sharp) flash exposure over the ambient. Experiment with the ratios between both exposures; you may even want to go down to -1.5 or even -2 for the ambient, especially if there's lots of sky in the scene.

okay, thanks, I also think that I need to underexpose a lot more.

You need a much more powerful flash.

in that case, I worry that I could overexpose the subject

 

[Pieter12]

Set your camera to underexpose by 1 stop, the flash set for proper exposure, Also, if possible set the flash synch to rear curtain, firing the flash as the shutter closes so the blur follows the subject.
(Not the best example)

 

[koraks]

okay, thanks, I also think that I need to underexpose a lot more.

Yeah. I'd also practice with digital. Learning this works a lot faster if you can see what you're doing.

 

[ic-racer]

okay, thanks, I also think that I need to underexpose a lot more.



in that case, I worry that I could overexpose the subject

More powerful flash will make you use a smaller aperture, which will make the available light portion of the image dimmer and the flash portion of the image more prominent.

 

[BrianShaw]

A flash meter is an incredibly useful too for this kind of application!