AUTO mode or manual for off-camera lighting?

Hi all!
I have a Pentax Af360 and a Sigma 530 Super. I'm trying to figure out if I can reliably use the AUTO on the flashes to make sure I have the proper exposure for a set aperture.
When I tell my 360 to shoot out f8 at, lets say 10 ft, my meter reads it as a stop or two less than what I put in (close to f4.5 or 5.6). I'd hope that if I dial in f8 that I'd get f8. I know the meter's ok because I can take well exposed pictures with it using ambient light. And when I DO use the flashes on manual mode at a given power level then the exposure matches what I have on my meter (Minolta Flashmeter IV).

So, should I just stay in manual and adjust each flash's power to get the light I need? I wonder if thats the only way to stay consistent.

Thanks.

Manual, every time.

In auto mode, take one model, dress him/her in a black suit/dress, take a shot. Change the black clothes for white, take another shot. Compare the skin tones on each, they'll be different because the flashes have adjusted the power settings.

Now repeat in manual mode, skin tones should be the same.

In manual, you have control.

When you say "off camera", which camera, and with what are you triggering the remote flash?
Matt

I have the Pentax K200 and I use both the wireless function and/or the Ebay triggers. I'd like to try to streamline my process and I wasn't sure if using the AUTO was a "cheat" so that I wouldnt have to keep metering when I change light locations. However, I think Mannesty is right. Sometimes Manual is the best way to go.

If your location is fixed - use Manual
If your location is not fixed, then use Auto but shoot RAW to give some latitude

The wireless function of the K200D will use P-TTL, and you should set up the AF360 to Slave 1 (IIRC) - ie P-TTL remote. There is a preflash, and a main flash. If you try and slave to a "dumb" remote (e.g. AF360 on Slave 2 mode) then you may end up discharging the flash on the pre-flash trigger with nothing left for the main flash (and underexposure results!)... just in case you didn't know that

Matt

When I use the wireless on both flashes, the preflash is so dim and I think its a split second before the shutter opens that it doesnt show up in the picture. Which is great than having to go into "dumb slave"! Ugh, I hated that. The only downside is that it looks like the wireless function works on "line of sight" so the flash has to "see" the preflash from the camera. Outdoors, I just use the Ebay triggers so its not a big issue.

BTW, how much more latitude have you gotten in RAW as compared to JPG? I really haven't been able to recover parts of an image that are two stops over eV.

RAW effectively records 12-bits on all three channels. JPG has, at most 8-bits (but actually less on the blue channel).
You have more latitude for shadows though - totally blown highlights can't be recovered on either, but there's definitely more in RAW Aim to not clip highlights and they'll be easily recovered in RAW.
Matt

The preflash fires whilst the mirror is still down and before the shutter curtains start to move. You can see the preflash through the viewfinder.

The master/controller flash which follows, occurs when the shutter is open and triggers the wireless slave flash.

When set to master, the triggering flash contributes light to the scene. As a controller, it still fires and a very small amount of light illuminates the scene and depending on your flash to subject distance, may or may not have any real effect. It's quite possible that you'll see the controller flash as a catchlight in a subjects eyes though.

To prove this, take a shot with your camera and flash pointed at a mirror. Even when set as a controller, you'll see the flash in the image.