Ciao a tutti

ho un dubbio che riguarda il flash se usato in M alla minima potenza ovvero a 1/128. Dovrebbe essere la minima potenza del flash , mentre in realta se lo metto in TTL ( stesse condizioni impostazione della fotocamera) è DECISAMENTE meno potente dandogli la compensazione "minima " possibile. ( -5 ev) . per decisamente intendo qualcosa come uno stop o forse due. Il punto o dubbio è comunque questo. Un flash al minimo di potenza, sia manuale o automatico, dovrebbe essere comunque al minimo della sua emissione di luce e quindi dovrebbe dare un risultato uguale , cosa che infatti si verifica alla massima potenza in qualunque configurazione. qualcuno mi dice se sto sbagliando qualcosa o se c e un problema?

grazie 1000

claudio

mi scuso e mi autorispondo avendo trovato una domanda simile in un 3d inglese. sostanzialmente è cosi...la minima potenza del flash la si ottiene solo in TTL ( escludendo l uso dei gel e supponendo di essere gia al minimo iso)..ciao

the "Truth" is that the manual minimum setting is actually the minimum manual setting.

In other words, many flashes that can be controlled both manually and via TTL are capable of less power than the power used at the lowest manual setting. To use the flash at less power than the minimum setting that is available manually, the flash must be controlled through TTL. The easiest way to do this is by adjusting the flash exposure compensation downward. Note: The flash exposure compensation setting has no effect when the flash power has been set manually, it only applies when the flash is being controlled through TTL.

If you want to reduce exposure of areas illuminated by the flash and retain manual control of the flash, then either a reduction in ISO or a narrower aperture can be used. Filters that limit the amount of light passing through them could also be used. This would include either lens mounted neutral density filters or modifiers placed between the flash and the subject. You could also increase the distance between the flash and the subject. Any of these options could also affect other properties of the resulting image.

A modern flash gun like the 430EX II can output an almost infinite number of power levels between the maximum and the minimum powers within its capability. But building a user interface that would allow manual control to such a fine degree would be unwieldy and cumbersome. A good analogy might be a camera that can use stepless shutter speeds. When selecting the shutter speed manually, only 1/2 or 1/3 stops are available for selection because at some point the excessive number of choices would make the selection of any shutter speed a lengthy exercise. But when selecting the aperture and letting the camera select the shutter speed, the camera can quickly select one of a virtually infinite number of shutter speeds between each stop.