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Re: [OM] Hep! Dr. Flash needs... um, flash help

Subject: Re: [OM] Hep! Dr. Flash needs... um, flash help
From: Chuck Norcutt <chucknorcutt@xxxxxxxxxxxxxxxx>
Date: Tue, 30 Dec 2008 21:32:23 -0500
When I say flash auto mode I'm referring to the three non-TTL flash 
controlled auto exposure modes supported by the T-32.  The T-32 was not 
set to "partial power" it was set to flash controlled auto mode at ISO 
400 which was calling for f/8 at the camera.  The T-32's slider does not 
only control full and 1/4 power but also switches the three flash 
controlled auto modes in and out.  Since the flash thought the lens was 
set at f/8 when in some shots it was set at f/11 the exposure on those 
shots will be a stop short.

Dr. Flash

Steve & Alicia Goss wrote:
> Chuck-
> Not exactly sure what you mean by the T-32 not being in TTL mode versus 
> auto mode. The T-32 really isn't that sophisticated.  The only real 
> control is the slider that controls how much power it puts out. The only 
> thing that switching the panel over to "Auto" does is ensure that the 
> power switch is set to full output.
> So if you had the T32 set to partial power, and the lens got moved to 
> f11, those may be underexposed, if using all of the partial power wasn't 
> enough for the situation.
> At least, that's my theory. The big question will be answered when the 
> roll gets developed.
> Thanks, Steve Goss, Dallas Tx usa
> Chuck Norcutt wrote:
>> OK, I think I have this figured out.  I finally found the reference to 
>> the fixed 1/60 second shutter speed with a T-flash attached.  It's in 
>> the eSIF.  It does not appear in the OM-2/2n or T-32 manuals. 
>> Furthermore, it's specific to the OM-2n.  The OM-2 does not do flash 
>> ready, does not know the flash is there and doesn't force the shutter 
>> speed to any specific value.
>> Yes, the camera does show "flash ready" with both body and flash in 
>> their respective auto modes.  That should mean that the camera has 
>> recognized a T-flash unit and, since the ambient light was well below 
>> 1/60 second, it has set the shutter to 1/60.  Since the camera is in 
>> auto mode and has sensed a T-flash it will assume that the T-flash is in 
>> TTL mode... it has no way of knowing that it's not.  When the flash 
>> fires, the camera will issue a quench signal to the flash when 
>> sufficient light has been received.  However, since the flash is in auto 
>> and not TTL mode the flash isn't paying attention to the quench signal. 
>>   It will do its own thing according to the indicated ISO and aperture 
>> on the calculator panel which was showing ISO 400 and f/8.  Those 
>> exposures taken at f/8 should be properly exposed.  Those exposures 
>> taken after the aperture ring was accidentally shifted to f/11 will be 
>> underexposed by one stop.  As Wayne indicated that's not much of an 
>> error for color negative film.
>> Dr. Flash
>> Moose wrote:
>>> Chuck Norcutt wrote:
>>>> I decided to go retro at Christmas dinner tonight so took out the 
>>>> pristine, black OM-2n and a T-32 and a roll of Kodak NPS 400....
>>>> What I *think* should happen is that the camera will see the fairly low 
>>>> ambient light around the dinner table and, at f/8 or f/11, despite the 
>>>> ISO 400 film, will decide to use a shutter speed somewhere around 1/15 
>>>> second or so.  
>>> Did you see a flash ready light in the viewfinder? If so, you should get 
>>> 1/60 shutter speed. The flash ready signal is how the camera knows there 
>>> is a T flash attached.
>>> The T32 manual shows the viewfinder flash confirmation light indicating 
>>> flash ready and flashing to show adequate flash exposure in flash Auto 
>>> mode on the OM-1n, so the flash ready indication does indeed operate in 
>>> flash Auto mode. There wouldn't be any point in the OM-1n otherwise. 
>>> That should cause the OM-2n in camera Auto to set a fixed 1/60.
>>> A. Flashy Moose
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