Curt & Sally Hedman wrote:
> Do the Olympus DSLRs provide true TTL flash metering, or do they resort to a
> pre-flash system like N*k*n's iTTL, C*n*n's E-TTL, and P*nt*x's P-TTL? I
> believe that early P*nt*x DSLRs used true TTL flash
> exposure control, but the current lines have gone to the pre-flash
> technique... as I understand it, the problem with true TTL flash metering
> with digital SLRs is the specular reflectivity of the imager and it's
> protective filters, or so say the pre-flash proponents.
Might you be confusing two technologies here? It's easy enough for those
of use who spent many years with OMs. Oly's TTL, starting with the OM-2n
was not just Through The Lens, but also Off The Film.
"True TTL" without the OTF simply means exactly what the acronym says,
the measurement is through the lens, rather than via a sensor on the
flash. So in fact, the only practical way it can be done without
calibrated modeling lights is with a pre-flash to allow measurement.
Any other, real time, means with the mirror up would interfere with the
light that's is making the image.
Well, OK, you could do it with something like the Canon Pellix, but that
has it's own compromises. <http://en.wikipedia.org/wiki/Canon_Pellix>
I'm not aware of anybody implementing TTL-OTF on a DSLR, although I
don't know everything, for exactly the reason you give.
Moose
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