A Puzzlement with flash sync

[austastar]

Hi,
This one has me foxed - can't figure why some thing that worked with one camera can't be repeated.
The story:
· I was using an early digital point and shoot Canon G2 in a studio with a pair of Elinchrom 11 studio flash units.
· I set the camera on manual 1/100th and manual f8 with flash on.
· By shielding the camera flash with my hand, there was enough residual light to sync the studio flash heads with out any unwanted light from the on camera flash.
· This gave me the lighting I wanted and worked for years, giving me freedom from the nuisance of sync cords and hot shoe adaptors.

The problem:

I have tried to do this with other cameras with out success, the studio flash heads fire, but are not recorded in the resultant image.

I have tried:
· Camera is a Sony cybershot and has no flash shoe or pc connection.
· A range of shutter speeds from seconds to 1/100th.
· 'Brief' and firing the flash heads manually will record the flash lighting.

Any thoughts, musings, inspirations, precise instructions, mystical chants etc will be read with interest.

cheers

[tomalophicon]

An odd one.
Are you able to set the Sony to manual mode?

[austastar]

Hi,
Yep, that's how I get the range of shutter speeds, and I know that f8 is a good setting for most studio work around 2m from the reflectors.

It is almost like the studio flash is going off before the shutter opens, and the only way that could happen is if the camera flash has some sort of 'pre flash' like a red-eye reduction that is so fast I can't see it.



cheers

[vnx205]

What flash settings do you have available?
Can you change this setting?

Rear and Front Curtain Sync
If your camera gives you some manual control when it comes to slow sync flash you might find yourself presented with two options called ‘rear curtain sync’ and ‘front curtain sync’.
These two modes sound a little technical but to put it most simply they are the way in which you choose when to fire your flash during the longer exposure.

Rear Curtain Sync – this tells your camera to fire the flash at the end of the exposure. ie when you press the shutter your lens opens up and starts collecting light and just before it closes the flash will fire to light up and freeze your main subject (see the card shot to the left for an example where you’ll see the card trail ending in a nice crisp shot of the card).
Front Curtain Sync – this tells your camera to fire the flash at the start of the exposure. ie when you press the shutter, the flash will fire immediately and the shutter will remain open afterwards capturing ambient light.
You might not think there’s much difference between these modes but when you’re photographing a moving subject it can have a real impact. You’ll find many action/sports photographers will use Rear Curtain Sync when shooting with a panning technique.


Read more: Slow Sync Flash (http://www.digital-photography-school.com/slow-sync-flash#ixzz1oUr3haZ9)

[austastar]

Hi,
Yes, I've used the different flash sync settings on a couple of Nikons (I'm familiar with focal plane and synchro compur M and X settings on film cameras)
I don't have these options on the Sony point and shoot (http://www.digitalcamerawarehouse.com.au/prod7426.htm), so I'm trying to use the on camera flash to trigger the studio flash heads.
In fact I haven't a clue how the shutter works on a digital camera, or if they even have a physical shutter.
How, when and what synchronises the camera flash with the exposure on a digital point and shoot camera is what I need to understand so I can do things with this camera that I used to do with a much older Cannon G2 point and shoot digital.
cheers

[tomalophicon]

I'd stick with your old leaf shutters if I were you. Sounds like much less hassle :)

[austastar]

Hi,
Oh I wish!

I'm thinking of setting up another camera to record a ball being dropped.

The idea is to have the room dark, set up the Sony camera to light the ball and trigger the studio flash, also lighting the ball.

Have the second camera on Brief, drop the ball and press the button on the Sony and hope the over-intelligence electronic instrument of the devil will expose an object that is moving and it can't see.
If the studio flash fires (which it should if the Sony flash fires), the resultant image in the second camera of the position of the ball and its lighting should tell me where in the sequence the flash trigger times are.

Grrrrrrrrrrrrrrrrrrrrrrrrr! make something idiot proof and only idiots will want to use it.

cheers

[austastar]

Hi,

8<------------------------------

The flash systems that is part of modern camera systems uses something called TTL metering to control the power-ratio of dedicated flash units. An important part of TTL metering is the use of pre-flash. It works like this: The camera fires one or more low power pre-flashes milliseconds before the shutter opens. It then measures the light from this pre-flash as it is reflected from the subject through the lens (TTL). The camera uses this reading to compute the power ratio for the flash for correct exposure. The camera communicates the desired power-ratio to the flash and the flash adjust its power accordingly. Finally, the camera opens the shutter and fires the flash to make the exposure. This system provides a fully automatic exposure control that seamlessly integrates camera and flash.
Unfortunately, the pre-flash sequence also trigger “dumb” optical slaves so that the flash units controlled by this type of slave trigger will fire before the shutter opens. In other words, TTL metering and “dumb” optical slaves don't mix.
8<-----------------------------------------


I guess the older Canon that I was using didn't pre-flash.


Hmmm! more ammo to use in getting a Nikon DSLR.


cheers

[mfc]

if you have an old flash laying round use it as the first light and to trigger the floor packs ,or a light meter to trigger all three...if youre going to try to capture several images of the ball falling you would have to expose it several times or flash it during the fall if the elinhcroms refire fast enough.id be thinking to get the camera as dumb as posible black out the room with the shutter open or on 2 seconds and using the flashes as youre shutter
The other thing to try is to wack a bit of celephane or jell over the floor packs and see if you get a cast the same color and do the same with the camera flash to see what /how mutch light comes from eatch light
One other thing is with the ttl metering make shure you dont cover a/the sensor if you do it will up the output of the floor packs and drown them out
{ smart dose tend to reduce youre options in a camera as far as im concerned} chears mark