Use camera's flash exposure compensation instead of external strobe to save battery?

[ScubaMarc]

The DIY version that I built is not much bigger than the standard hot-shoe adapter for TTL. The bigger issue depends on what housing and strobe do you have to get the LED light to the strobe.

Bill

G12 with oem case. Where did you get your instructions from?

 

[DazedAndConfuzed]

In the first post I thought the question was whether it made sense to reduce the flash compensation in the camera and increase the flash compensation in the external flash to save the camera's battery. For manual flash reducing the camera's flash to a minimal output makes sense as the external flash will fire for the duration dialed into the external flash regardless of the strength of the "trigger" from the camera's flash.

Lwang may be right that this approach will work and save camera battery power but for me it would be too complex. Keeping track of flash compensation this way when I am already narced would be a problem for me.

I usually only shoot about 40-60 shots in a dive and do 2 dives before changing batteries. For someone like me who only does 3 dives a day it is simpler to change batteries between the 2nd and 3rd dives.

I indicated both to decrease light output and possibility decreasing the internal flash output and increasing external strobe output, but my external strobe could only decrease in brightness, thus it is not possible with my setup.

I try to minimize opening up my camera's housing since there is issue of sand stuck on the outside of the o-ring getting pushing into the sealing area of the housing, along with worrying about condensation from humidity. I don't worry about that with the external strobe, who's o-ring is not exposed.

 

[Cjs_777]

As I understand it (and please, I'm no expert...) the internal flash merely tells the external strobe when to switch "on" and "off," in order to send the desired amount of light into the camera's sensor.

Therefore, increasing the strobe's brightness, would require a shorter "on" time to reach the same level of exposure- saving your camera's battery.

Similarly, reducing the photo's exposure level via the camera's exposure and/or flash compensation would result in less light required, and therefore a shorter "on" time- again, less strain on the camera's battery. Overdoing this would however result in under-exposed photo's...

 

[DazedAndConfuzed]

As I understand it (and please, I'm no expert...) the internal flash merely tells the external strobe when to switch "on" and "off," in order to send the desired amount of light into the camera's sensor.

Therefore, increasing the strobe's brightness, would require a shorter "on" time to reach the same level of exposure- saving your camera's battery.

Similarly, reducing the photo's exposure level via the camera's exposure and/or flash compensation would result in less light required, and therefore a shorter "on" time- again, less strain on the camera's battery. Overdoing this would however result in under-exposed photo's...

Its kind of what I am saying. The only way for an external strobe (or any strobe/flash) to be brighter is to stay on longer. So there you can't use shorter 'on' time on the external strobe. It all has to do with the pre-flash and main picture taking flash. The pre-flash tells the camera how much bright the picture taking flash has to be to take the picture, thus in scenario one above, you are telling the camera you want a darker picture, and after all the pre-flash goes off and the camera calculates for a darker picture, the external strobe shoots extra bright and you end up with a properly exposed picture.

 

[bvanant]

You are correct, the control circuitry does indeed tell the strobe how long to stay on but I don't know what you mean by "increase the strobe brightness". In any case I suggest shooting your strobes in manual and trigger with the lowest trigger power you can (1/128 or so) as the best way to learn.

Bill

 

[bvanant]

I got hold of an old cheap strobe and took the hot-shoe connector off of it, went to Radio Shack bought some LEDs and hacked around to get a pulse. No circuit involved just put the + battery voltage in-line with the hotshoe contact.

Bill

 

[DazedAndConfuzed]

I got hold of an old cheap strobe and took the hot-shoe connector off of it, went to Radio Shack bought some LEDs and hacked around to get a pulse. No circuit involved just put the + battery voltage in-line with the hotshoe contact.

Bill

Is this just to trigger the external strobe or does the LED replicates the electrical pulse well enough that it could utilize those strobe's optical TTL feature?

 

[Ardy]

Lwang - I checked this on my camera as I am interested in saving camera battery but mine does not work like this. If I adjust my internal flash output then the TTL to the external flashes is likewise reduced giving an underexposed image. I spoke to a mate of mine who uses Nikon and he has reduced flash output settings that puts out the TTL codes for a normal exposure. My Olympus does not put out TTL on reduced manual output which means the SnS110a and the Inon Z240 need to be set manually, not a great problem but I am having a little love affair with my Z240/110a and TTL. Still regardless of the battery drain it still lasts above 300 exposures which gets me through a day even if it didn't, changing batteries between dives is not the end of the world.

 

[bvanant]

No indeed it is a cheap trigger only. To get it to work in TTL mode would be far beyond my capabilities (and everyone else's for that matter) since LED modulation by pulsewidth is very complex.
Bill

 

[Cjs_777]

You are correct, the control circuitry does indeed tell the strobe how long to stay on but I don't know what you mean by "increase the strobe brightness". In any case I suggest shooting your strobes in manual and trigger with the lowest trigger power you can (1/128 or so) as the best way to learn. Bill

Sorry about that, I meant using a stronger strobe- although that's slightly off the OP's original question