Olympus-OM
[Top] [All Lists]

Re: [OM] F280 & multi-spot

Subject: Re: [OM] F280 & multi-spot
From: frieder.faig@xxxxxxxxxxxxxxxxxxxxxxxxx
Date: Tue, 23 Apr 2002 16:12:23 +0200
On Tue, Apr 23, 2002 at 08:18:21AM -0500, gries wrote:
> I am glad to see such a thorough discussion on one of my most
> mis-understood subjects.

Yes, F280 operation was mysterious to me too, slowly it is 
getting somewhat clearer.
> 
> Let's try to put this in practical terms.  Say that I am just walking
> around and need to get that fill flash on the dark side of an object
> whose background is quite bright (a person in from of a sunset for
> example).  If the scene meters 1/1000 at f11, but the chart shows me
> that the super FP output is best at a distance of approx. 1 meter, how
> do I photograph something that is 2 meters away? 


When you use the F280 in manual mode, set the camera to 1/1000
and F11. Your person will be underexposed 1 stop, which is a good 
amount to keep the shadow atmosphere of the person.   ;-) 

 >Do I change the
> shutter speed to 1/500 as indicated in the chart?  Wouldn't this then
> make the background 1 stop brighter?  
Yes. Your whole image will be one stop brigher -until you adjust the aperture
to F16, which will eat up your gain from choosing the slower shutter speed.
The foreground/ background ratio will still be 1 stop difference.

>  How can I make accurate judgments of how the flash
> will perform?

Only with guide number calculation like acting a flash in manual mode.
The interesting part is, that the guide number if the F280 decreases
with exposure time, with the factor 1.4. The same value as the number 
of the f-stop decreases with one stop.
This reinforces the theory, that the F280 act`s like a additional continious
source of light. So the balance of foreground/ background illumination
can`t be influenced with the selected apperture/time combination.

> 
> Also, what is the affect of the F280 in Super FP mode with speeds below
> 1/60?  Will the frame only be partially exposed? 

Assuming the maximum FP-flash duration is 1/25 sec (40ms), and the fist curtain
needs 13.5 ms:  then ons side is illuminated 40ms, the other 26.5ms. So the 
maximal illumination difference detween left and right is 1:1.5,  this is about 
1/2-stop. 
I think this is not visible in most 3D-subjects.
 
> Is the motion blur possible?
Yes, motion blur was a strong argument in olympus advertisments for the 
FP-flash.

Frieder Faig

< This message was delivered via the Olympus Mailing List >
< For questions, mailto:owner-olympus@xxxxxxxxxxxxxxx >
< Web Page: http://Zuiko.sls.bc.ca/swright/olympuslist.html >


<Prev in Thread] Current Thread [Next in Thread>
Sponsored by Tako
Impressum | Datenschutz