Questions about using TTL compatible Flash with OM-2S and OM-4T

My question or lack of understanding is simple(I think), when using a

TTL compatible flash with either an OM-2s or OM-4T body, the camera

will determine the duration of the flash based solely on the amount of

light it see reflected off the film ? Therefore the angle of the flash

lamp, diffuser (on of off), etc. does not matter, all that matters is

that it sees enough light to expose the film properly. I mainly use a

Vivitar zoom thyristor 5200 flash with the Olympus module,

occasionally I use an Olympus F280. On the Vivitar flash, I can punch

in ASA, and F-stop, does this have any effect on the light output in

TTL mode or is it just to give me the range in which the flash can be

used ? Any information on this topic would be helpful- Thank you.

In TTL mode all flash control is given over to the in camera sensors. Without being familiar with your specific flash, I can say that generally, yes, in TTL mode the on flash controls are only giving you information about the possible range of operation. Likewise in manual mode, where the light output is determined only by the setting you choose, regardless of any ASA or f-stop settings. Of course in sensor autoflash mode those controls make all of the decisions.

I also can't speak for that Vivitar flash. With the Olympus flash units, in TTL mode you set the camera on AUTO and the flash on full-power MANUAL. This allows the camera to control the flash through the signal line in the shoe. I would assume that with the Vivitar it would work the same way, in order to be compatible with the Olympus TTL control system. Setting the flash to AUTO (other than a specific TTL setting) will conflict with proper TTL operation.

 

:)=

Just as a side question (although I am sure it has been asked before). Are there any other flashes (third party) that can do the fast sync with the OM-4Ti (i.e. faster than 1/60 sec flash sync).

 

Or is the F280 the only one that can do it?