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Re: [OM] OTF light metering

Subject: Re: [OM] OTF light metering
From: Richard Schätzl <Richard.Schaetzl@xxxxxxxxxxxxxxxxxxxx>
Date: Wed, 08 Apr 1998 17:00:38 +0200
Miguel wrote:
> 

> When we use Olympus  F280  synchro flash  in auto mode with  OM4ti,
> selecting SuperFP or Normal OTF, the camera will calculate  a right
> exposure, metering the incoming light reflected by film plane.

I doubt, that, in FP mode, the camera calculates the amount of flash
light by metering the film plane. The reason is, that, in FP mode, the
"flash" will be made of many thousend, folowing flashes, these have to
be of the same strength and should not stop before the shutter is closed
to achieve an even exposure.
But maybe there is an "calculating" before the shutter starts, based on
the image projected on the shutter curtain patern. Does the OM-3Ti have
a pattern on the shutter curtain?
Is there someone who knows how the FP exposure is calculated?

> I have  noticed  how in night  photography, when I take a  portrait
> with my 50mm/f1.2, enhancing the subject but also background is out
> of focus  with  a  colourway of typical circles of confusion due to
> the low light. In order to blur the background, using a short focal
> distance I must go close to subject and select f1.2 to get the back
> blurred.
> Here is my doubt,
>         If  my camera meters  the light (center-weighted) resulting
> 1/8s  but  the  subject is only 0.60m  from my camera,  the shutter
> curtain  is  going  to close  as  soon as  the light beeing metered
> by OTF(off-the-film)system has properly exposed the film; resulting
> my  background  rendered  in  rich  black,  due  the camera shot at
> 1/60. This  sytem is great because you avoid an overexposed picture
> but;
> -------------------------------------------------------------------
> How can you balance the light  from  something close the camera and
> the background?

Switch to Manual mode, your flash will sync with all shutter times below
1/60s for TTL flash and all times for FP. The F280 will have a guide
number of "28" for full flash and "14 to 2,6" for FP flash.
You have to chose a aperture matching your subject distance and the
amount of subject ilumination you want. The shutterspeed has to be set
to achieve the wanted background ilumination (use the camera meter).

With an flash with build in "computer", eg. T32, you are able to choose
one of the computer apertures and don´t have to worry about the subject
distance, because the flash will limit the output automaticly. 


> When I used  to  shoot with my OM-1  with my flash sync to 1/60 and
> I had to choose the right aperture according to distance to subject
> I never thought about  hand-shaking, but with  this  system I never
> know at which shutter speed is going to take the picture.

With Auto mode the TTL sync time will be 1/60s, the FP time will be the
time shown in the finder.

 
> Dave

Dave or Miguel? 

> OLYMPUS FOREVER!!!

Ok

Richard (orang Jerman, ..bukan bisnis)

"Saya bukan orang Belanda"



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