Wacky flash exposures

[Joe Peoples]

I shoot 99% of my flash photos on Auto, f8, camera on Manual, f6.7, 1/30th, which varies depending on ambient light or Rear Curtain gimmicks, and have had good success with this recipe. There is one venue that drives my rig absolutely NUTS and I'm baffled. The large meeting room is painted white, with grey rugs. All of the images closer than 8' are overexposed, and I had to compensate on the fly by stopping down up to 1 stop. I had the flash on "Slow", as I had shutter speeds slower than 1/30th on my last gig. Today, I upped the speed to 1/125th for proper exposure outside the windows (of which added no significant exposure). I took the flash off of Slow and I think the exposures were somewhat tighter, but why would this have an effect if I'm using manual settings?

Many of the people had dark suits. Could the higher contrast of the situation make the flash wig? The shots where people were in the middle of the room had the most variation in exposure. Camera was on matrix metering. Thanks for any insight.

[memobug]

Hi Joe,

I am trying to understand your message, but frankly I can't make much sense out of it.

First off, you can't shoot slow sync in Manual mode. The camera won't even let you turn it on. You can only shoot slow sync in shutter variable modes like Program and Aperture Priority.

Second, I don't understand the "99%....which varies" part.

Third, I am confused why you changed the shutter speed to "1/125 for proper exposure outside of windows (of which added no significant exposure)"

It's late and I am trying to understand, but I'm confused. Maybe you can rewrite this or someone else can have a crack at it.

In general, if you are in 3D Matrix Metering, the camera is going to try to make object(s) in the foreground 18% grey. That might lead to some misexposure if the objects are dark in color. Also if your ISO is set pretty high it may not be able to quench the flash soon enough before overexposure occurs.

Good luck,

Matt