Vivitar DF-383-PEN flash question

[raybrizzi]

<p>I know very few people will have this model flash, but it may affect other flashes as well. When I use the flash on my K-5 with P-TTL, it picks up the ISO, focal length and f/stop fine and shows it on the flash. But the shutter speed is set to a firm 1/90. Why not 1/180? Is it the flash or the camera that sets that speed? Is there an option I'm missing somewhere?<br>

If I use x-sync, it goes to 1/180. </p>

[raybrizzi]

<p>The other day, I was shooting outside trying to use the flash just for fill, and it was locked at 1/90. Now that I'm trying it at home, it went to 1/125. Wish I understood the logic... this is AV mode set to f8. Will try some other testing.</p>

[pj_vesterback]

<p>You are shooting in Av so the camera decides that 1/90s is the best exposure. If you want to control the shutter shoot in Tv or M or X.</p>

[andrewg_ny]

<p>You'll probably find that it's selecting 1/90 due to the available light and focal length of your lens.</p>

[mc2imaging]

<p>Shutter speed has no effect on flash exposure, only ambient light (as long as you are at 1/180 or slower). As PJ said, if you want to control shutter speed, you have to get out of Av.</p>

[rumaweigh]

<p> I use the same flash on my K-5 and note some inconsistencies. I am not certain of this and you might want to test it. But my impression is that 1/90 is the highest shutter speed to allow P-TTL. In manual 1/180 is allowed. Might have something to do with the back and forth communication needs of TTL.</p>

<p> </p>

[raybrizzi]

<p>No, it was using 1/125 another time. So apparently it's the camera, not the flash. I personally don't see why it just doesn't use 1/180 all the time for flash if it can so you can use it for fill without having to have blurry pictures on an arbitrary design whim.</p>