Pre-Flash Confusion

This may be a neewbie question but here it goes. OK, so if a digicam uses a pre flash to measure exposure then how does this work if you have the built in flash covered by an slave/optical/etc sensor to prevent backscatter when using a strobe? In other words, you can get the strobe to fire using some sort of slave but if you cover the built in flash then the function of the preflash is negated.?.?.?

JS

The External flash copys the preflash and giv so the needed light for the exposure measurement. Thats why this only works with Flashes that are build specially for that .

Simon

OK, so if I understand you correctly; strobes that are built specially for digicams reproduce the preflash? If this is the case, who makes these "special" strobes? Are there any other options?

JS

Ikelite has the DS125 and DS50 in combination with a TTL Sensor

Sea & Sea has the YS25DX and the YS90DX with a fiber cable

and I think there is also one made by Epoque (Also Fiber Cable)

Simon

Sea & Sea has the YS25DX and the YS90DX with a fiber cable

The Sea&Sea flashes don't have TTL option, they can configure to ignore the pre flash and fire only at the second fire. They don't stop when the internal flash stop but continue firing the all amount of light according the power settings they have.

Ooops you are right the TTL ist only available via the Iklites and thge TTL Sensor.

Simon

Thanks for the help so far. So if the preflash is ignored then that means the strobe fires at the preflash and continues until the normal flash is done? Does this give proper exposure (since the camera is setting the exposure settings @ preflash)?

JS

If you don't use the Ikelight with TTL I think you have to do the exposure Manually

Simon

The Sea&Sea YS90DX does have a TTL setting.

But does this work via the preflash or just if i wire it to traditional TTL film Camera?

Simon

This only works with a camera that is NOT using preflash. Not all digicam use preflash. Using an optical or hardwire sync is not the issue, the preflash is. Sorry if I mislead you by saying that the 90DX has TTL. Th TTL function only works with non preflash cameras, digi or film.

Ikelite has the DS125 and DS50 in combination with a TTL Sensor

Sea & Sea has the YS25DX and the YS90DX with a fiber cable

and I think there is also one made by Epoque (Also Fiber Cable)

lets us not forget about Inon strobes......

my spezial tipp-> look at :

http://www.muenster.de/~matthias/blitz/indexe.htm (english)

http://www.muenster.de/~matthias/blitz/ (german)

Is the best solution, IMHO

Best regards, obi