Hi AG and all,
> From: Ken Norton
> To a couple specific points: My OM-2S is particularily moody when it comes
> to TTL flash in Aperture-Priority Auto mode. If the ambient is 1/60 the
> flash may fire, but if it registers faster than 1/60 the flash will not
> fire.
It's a reasonable behaviour: if speed is over 1/60 with ambient light, it
seems that there is "enough" light for not using a flash... and anyway,
firing it over 1/60 with the OM shutter would expose only partially the
frame.
Please note that the old OM-2(n) had speeds in the viewfinder scale printed
in blue... up to 30 -- if the needle was near 60, that means that the flash
could o could not fire. Don't forget that viewfinder indication comes from a
different light meter, and it's not unusual to have some discrepancy between
them (eg. the needle near 30 but the OTF cutting about 60)
> If I stop down the lens to drop the non-flash exposure to 1/60 or slower I
> am unfortunately reducing the effective flash-to-subject distance.
But that's a law of optics... a powerful flash is always a great help.
> I will specifically use flash with the ambient overexposing. This is common
> with outdoor portraiture where my subject is shaded, but the background is
> in bright sunlight. I'll usually overexpose the background by around a stop
> and let the flash properly expose the subject.
I understand, but franky don't know how could it be done with TTL...
> When shooting indoor weddings, for example, I like my room exposure to be
> one or two stops underexposed.
Very reasonable.
> If I was running everything manually, I'd set the aperture, for example at
> F5.6, and with ISO 400 film a PROPER ambient exposure would be 1/15.
But you don't want the ambient to be correctly exposed, do you? I understand
you are aiming at a 1-2 stops underexposure.
> But with the OM-2n, OM-2S, OM-4(Ti), when shot in Auto-mode, the camera
> will override shutterspeed and force a 1/60 thus putting the background
> (ambient) two stops under exposed.
And isn't that what you were looking for? I'm I bit lost here, sorry...
> But with the OM-2, it is possible that not enough reflected light from the
> flash occured and the camera will drag the shutter longer which brings the
> background up AND ends up giving your subject too much mixed (flash +
> ambient) lighting and throws your colorcasts off.
Well, the OM-2 behaviour here is an "anti-feature", I admit... However,
turning the lever to OFF may be a workaround. But if the flash dump wasn't
enough, you probably would need to repeat the shot with different settings,
anyway.
Why not forgo auto exposure and just use manual exposure you ask? Because if
> the flash does not fire, the auto-exposure will compensate and will still
> properly expose the image.
That's a good point. Enough light? No flash. Low light? Fire the flash. Low
light and flash dump not strong enough...? Well, you're in trouble then ;-)
> The above description points to one of the most incredible usability
> features of the OM series. In Aperture-Priority, the exposure scale ALWAYS
> indicates what the exposure would be if the flash did not fire. Knowing that
> the camera will fire at 1/60 means that you just watch the scale and adjust
> aperture to put the needle or bargraph at the desired speed in relation to
> 1/60.
Seems an easy way to control the balance between subject/flash exposure and
background/ambient exposure -- provided the subject covers a significant
area of the picture.
> As a side-note, the in-flash auto-exposure of the T45 works as well, if not
> better than OTF, except when under 10 feet from the subject. Olympus got the
> in-flash auto correct.
The in-flash auto sensors usually have a relatively narrow angle of view, so
they are kind of spot-meters, which is interesting sometimes.
Cheers,
--
Carlos J. Santisteban Salinas
IES Turaniana (Roquetas de Mar, Almeria)
<http://cjss.sytes.net/>
--
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