-----Ursprungligt meddelande-----
Från: Giles <cnocbui@xxxxxxxxxxxxx>
Till: olympus@xxxxxxxxxxxxxxx <olympus@xxxxxxxxxxxxxxx>
Datum: den 9 januari 1999 23:35
Ämne: Re: [OM] TTL FUNCTION
>The OM2, 2n, 2Sp, 4, 4Ti and 3Ti - there may be others (PC?) - all
>have TTL flash control, and except for the 3Ti, OTF metering. The
>3Ti and 4Ti also have Super FP capability.
>Off The Film (OTF) metering is operational in auto mode in the above
>cameras. It works thusly: There is a silicon sensor in the bottom
>of the mirror box - behind and beneath the mirror. This points
>towards the back of the camera and measures light reflected off the
>film during the actual exposure ie. while the shutter is open and the
>mirror is up. It only functions in this way when the exposure is
>1/60th sec or longer. For shutter speeds faster than 1/60th the
>exposure is calculated by meaasuring the reflection from a black and
>white pattern printed on the front of the shutter curtain before the
>shutter opens.
>TTL is a sort of variation on OTF. When the shutter is open and the
>flash fires, the silicon cell measures the light being reflected off
>the film. When it is determined that enough light for a correct
>exposure has reached the film the flash is turned off before it
>delivers its full potential and the shutter is closed.
>TTL and OTF work very well, especial for macro photography.
>With TTL, the fastest shutter speed a flash can be used with is
>1/60th. With Super FP faster shutter speeds can be used but
>Super FP only works with the 4Ti and 3Ti. The IS series cameras can
>also use Super FP with the G40 flash.
>Super FP is apparently not as wonderful as it may sound at first as
>the F280 is considered by most to be a bit weak so it is limmited in
>practical use to short ranges.
>Giles
An excellent description of OTF, TTL and super FP except for... Sorry
Giles, the G40 does give you much but not super FP flash. In the IS
series this is exclusively with the built-in G28 flash of the IS-3000
(not IS-3). As you probably also know the IS series do not have TTL
flash. Instead they use an intelligent variant of the old flashmatic
system.
Per Nordenberg
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