fotolistaRe: fenykepezo + paka

[Topybear]

At 13:32 2005.01.28.ö, you wrote:
>hi,
>
>megprobalom nemfolytatni, de nem megy.
>
>valahogy ugy volt, hogy a n verte a nyalat, hogy ez milyen piszok jo, a c 
>meg nem strapalta magat, hanem elindult elovillantas iranyba es kesz.
>
>aztan jottek a digitalis gepek, es a nikon bajban volt, mert a ccd-rol 
>b at szik visszaverodni a feny. erre o is nekiallt elovillantani, es mivel az 
>ettl mar foglalt volt, elnevezte dttl-nek meg ittl-nek, meg a fene tudja 
>hogy minek. a lenyeg hogy mindenki masnak hivja, a minoltanak is megvan a 
>sajat roviditese ra.
>
>persze a nikonnal a digitalisak is a redonyrol visszaverodo fenybol mernek 
>kozvetlenul a nyitas elott. a belelepnek a kepbe cuccnal eletszerubb 
>mondjuk a koncerten fenykepezes, ahol orrba szajba villognak a fenyek, es 
>a manual fenymerest nyugodtan a hajadra kenheted.

Dióhéjban összefoglalva :)))):

"TTL metering is more reliable than systems which rely on external sensors, 
but it can still be fooled. For example, a highly reflective subject or a 
subject in white surroundings can result in a lot of light reflecting back, 
so the resulting picture may well be underexposed as the camera quenches 
the flash too soon. An off-centre subject poses similar problems. Another 
issue is that the flash metering occurs while the shutter is open, so the 
camera can’t accurately factor flash in with ambient light metering.

Canon refined TTL control on their multiple focus point cameras by adding a 
feature they call AIM, (“Advanced Integrated Multi-point Control System”) 
which is basically multiple-segment flash metering. This lets the camera 
bias the flash exposure to the currently selected focus point, thereby 
increasing the chances of getting accurate flash exposure for off-centre 
subjects.

The AIM system means that it’s best to rely on selecting off-centre focus 
points for flash photography rather than using the centre point and then 
recomposing the image. (unless you use flash exposure lock, explained 
below) For more information on AIM consult the flash metering patterns 
section. Note that older EOS cameras with multiple-segment flash metering 
didn’t use the term “AIM” in their documentation - Canon came up with the 
marketing term sometime in the mid 90s - so the fact your multiple focus 
point camera doesn’t mention AIM doesn’t mean it hasn’t got it.

Nikon improved their TTL flash metering system by incorporating subject 
distance into flash calculations - their “3D” system. This system 
determines distance information by reading the current focussing distance 
from the lens. Canon did not incorporate a similar distance-data system in 
their flash technology until 2004, with the introduction of E-TTL II. 
However, while distance data is valuable, it’s important to keep in mind 
that distance data isn’t very useful when using a flash in bounce mode or 
when using any diffusion system in which the light from the flash unit does 
not travel directly to the subject, since both cases increase the flash to 
subject distance over the lens to subject distance. "

Topy