Flash not syncing??

[Dman]

I've got the Elemental G2 kit, only used it half a dozen times and all was going well this evening doing some test shots, but all of a sudden I gave one of the lights a very slight tweak in power and all of a sudden the flashes no longer sync.

Everything is connected up ok and the main flash works fine on it's own, but it just won't trigger the other flash at all. The non-triggering flash works of it's own accord when either the test button is pushed or it's the main lamp plugged in, but I don't know for the life of me what's happened!

Any ideas??

 

[Dman]

Ok, an update!

They sync when the modelling lamp on the second light is turned off, but as soon as I switch it back on, no flash?!

 

[Garry Edwards]

The modelling lamp is creating the problem and is fairly common. If it's shining too brightly on the sensor of the second flash, the sensor isn't 'seeing' the flash from the first flash.

Either turn off the modelling lamp or fit a physical shield to block light from it hitting the sensor. You'd get the same problem if direct sunlight hit the sensor.

 

[Dman]

The modelling lamp is creating the problem and is fairly common. If it's shining too brightly on the sensor of the second flash, the sensor isn't 'seeing' the flash from the first flash.

Either turn off the modelling lamp or fit a physical shield to block light from it hitting the sensor. You'd get the same problem if direct sunlight hit the sensor.

Lifesaver! It was actually the umbrella on the second bulb blocking it, I'm trying out some different things!

While I'm at it Garry, do you think it's best to go one or two stops brighter for a white background? I've a two light setup so very basic, but I seem to be getting the best results with a background of f/22 and subject of f/11, does that sound ok? Or should I try to go to f/8 with an f/16 background? What would you say should produce the better results?

 

[Garry Edwards]

While I'm at it Garry, do you think it's best to go one or two stops brighter for a white background? I've a two light setup so very basic, but I seem to be getting the best results with a background of f/22 and subject of f/11, does that sound ok? Or should I try to go to f/8 with an f/16 background? What would you say should produce the better results?

Background f/22, subject f/11 and background f/16, subject f/8 is exactly the same difference.

My answer to your question is that you need to get EVEN lighting on the background and then use the MINIMUM level of overexposure to get it white. If you can light the background evenly then a half stop will be enough. If you can't get it evenly lit then you will need a higher level of overexposure, and if your subject is too close to the background too much overexposure will produce poor results.

Probably the idean scenario is to put 2 or more stops of overexposure on the background and have your subject 6-7 metres away from it - when the light reflected from the background has to travel that far is ceases to cause a problem, but the reality is that most people have to manage with very little space, which is why I am saying that the level of overexposure needs to be the minimum possible.

 

[Dman]

Background f/22, subject f/11 and background f/16, subject f/8 is exactly the same difference.

I get less 'shine' on the face when using f/11 as opposed to f/8, the background is evenly lit with either f/16 or f/22 (I've just learned that turning the modelling lamps off and just firing the flash makes for a much more even and whiter background).

Unfortunately at home I don't have 6-7 metres, it's only an 8 foot train.