Another Flash Question

linpelk · May 1, 2009

Ok, when my flash is attached to the camera in the ETTL mode do I adjust for my exposure as if it's not there? I mean, do I look at my meter and get everything the way I would shoot it without the flash and the camera will adjust for the extra light from the flash? I usually shoot in Manual or AV mode.

Ok, if so, then I just have to look at the image on my LCD and determine if I need to adjust the amount of flash from that point depending on how close/far the subject is, etc. ?? I am just shooting away right now and trying all kinds of variations, but I feel kind of like I did when I first got my camera when I would just turn dials at random and hope for the best.

Here's one I just took attempting to bounce the flash off of the white wall to my left and window light on the right. I applied the method mentioned above. How does it look?

Pardon the wrinkly shirt..she just woke up from her nap..I snatched her up and sat her on the chair.

Big Mike · May 1, 2009

When I'm shooting with E-TTL flash, I almost always have the camera in manual.

I set the aperture for the DOF I want, keeping in mind that a smaller aperture will mean the flash has to work harder. The camera will match the flash's output to the aperture you have set. So as long as you don't exceed the flash's limit for power, you exposure should be the same at whatever aperture you choose.
To change the flash exposure, I adjust the FEC via the camera.

I set the shutter speed for the amount of ambient I want...slower for more ambient, faster for less. Keeping in mind that I probably don't want to exceed the max sync speed (although I could, with HSS mode). Also, keeping in mind that too much ambient exposure can cause blur at slower shutter speeds.

I adjust the ISO with ambient exposure in mind and also that the flash has to work harder at lower ISO.

To balance the flash with ambient, you are doing it right. Adjust the exposure settings for the ambient light and the E-TTL metering should give you light to match the aperture chosen.

Your sample shot looks great. Nice soft light with a subtle ratio across her face. Nice big catch lights too.

I don't know if you were just getting lucky or if you had this in mind...but flash and ambient light don't always match, in terms of color temp....which can cause your photo to have a color cast. In your case, the light looks like it matches very well though.

If you are shooting with different colored light, the solution is either to overpower the ambient with flash, or use a color gel to change the flash's light.

linpelk · May 2, 2009

Ok, so are you saying that I don't have to watch the meter so much to make sure I have a perfect balance of SS, Aperture, and ISO?? Instead, I just adjust the Aperture for the DOF I want, then adjust the SS for the amount of ambient light I want (up to 1/250)? So for ISO do I just analyze how bright/dark the environment is and adjust from THAT. Like an outside bright sunny would be 100-200ish and a pretty dark/evening/indoors event would be toward the higher end 600-800ish or higher??

After this, then I can adjust the amount of light emitted from the flash via FEC on my camera?

Please let me know if I am off in left field.

As far as the picture...I just got lucky I guess. I had no idea that the color temp wouldn't match. I was just trying to brighten up the other side of her face a bit.

Thanks SOOOOO much for your help!!

ANDS! · May 2, 2009

Pretty much. If you have your off camera flash in "Auto" mode (I dont know how Speedlites work), it will adjust the flash output from 1/1 (full power) to 1/64 (minimum power, whatever your minimum is) based on the exposure settings you have chosen for your picture. For instance it may have you at 1/8th power at a 1/200th of a second at F/5.6 and ISO400. However, if you lets say go to ISO200, and F/8 - you're flash will go to 1/2 power (from 1/8th to 1/4 to account for the one stop change of ISO400 to ISO200, and 1/4th to 1/2 power to account for the one stop change of your aperture from F/5.6 to F/8) to maintain a proper exposure.

Take your flash off automatic (if you can), and start playing with various power levels on the flash, and exposure settings - all this will start to make sense when you use some of your own shots. Just remember what Mike said, for your subject, aperture affects flash output (because the flash is firing so fast that it could care less about the shutter speed of your camera, along with whatever the flash is hitting, namely your subject) and shutter speed affects ambient (since it will be open MUCH LONGER than your flash and will overpower anything not hit by the flash).