expose for the background... how??

[joruiz]

okay, so I hear everywhere that when shooting people outdoors it's a good idea to expose for the background and use flash to light the subject, this way you get a nice background and nicely lit subject. So I tried that yesterday. I have a Rebel XTi, and was trying this with my Tamron 17-50 and speedlite 430EX. I couldn't get it to work. Here's what I did, please correct me if I did something wrong!

I aim my camera ( Ae mode, at f/2.8 ) so the frame is mainly covered with the background, in this case it was lighter, illuminated with more light than the people I wanted to shoot. It had some sky in it. I press the * button, so the camera would lock exposure. Then I compose my frame with the people I want to shoot, focus and.. shoot, using my 430EX with default settings (automatic, no FEC adjustments). I get a very overexposed picture (foreground AND background!). Second try, adjust FEC so I get less power from the flash, and it looks a little bit better, but not much.

Now I go to the Custom Functions on the camera. On the custom function related to the shutter/exposure buttons (I can't remember what function that is), I switch to 1, so the shutter button locks Exposure and the * button locks focus.... and it works!! but for me that's all backwards, I want to be able to lock focus with the shutter and exposure with the * button, and that's the 0 setting, the default. So I switch back to 0 and... it doesn't work anymore.

I then discover that when I press the * button to lock exposure, it doesn't lock. I mean, it gets a reading, but as soon as I recompose the frame, I get a different reading, it doesn't keep the original reading of the background, as if it isn't locking on the reading I want. So when I shoot, I get a much lower speed, with my flash on, and I get an overexposed picture. I hope that makes sense.

I don't know what I am doing wrong. Perhaps, if someone with an Rebel XTi would be so kind as to tell me what are the steps to do this right. It must be fairly easily, but I couldn't figure it out, to be honest, I didn't try for more than 15 minutes, my sisters (the subject) weren't willing to pose for a long time :( .. and the bad thing is that I misplaced the camera's manual. So... please

TIA!

Joel

[PhotosGuy]

Try using your camera on "M", & the flash on auto. If that doesn't work, put the flash on "M", too.
Need an exposure crutch? (http://photography-on-the.net/forum/showthread.php?t=89123)

See Curtis' post & post #4 here: Settings?? Help Needed! (http://photography-on-the.net/forum/showthread.php?p=2953374)
Includes "M" flash use & links to: Fill light at sunset

[tzalman]

I aim my camera ( Ae mode, at f/2.8 ) so the frame is mainly covered with the background, in this case it was lighter, illuminated with more light than the people I wanted to shoot. It had some sky in it. I press the * button, so the camera would lock exposure. Then I compose my frame with the people I want to shoot, focus and.. shoot, using my 430EX with default settings (automatic, no FEC adjustments). I get a very overexposed picture (foreground AND background!). Second try, adjust FEC so I get less power from the flash, and it looks a little bit better, but not much.
Joel

This is what is probably happening. First, I assume you mean Av mode, not Ae. When you set f/2.8 and measure the bright outdoors background you get a shutter speed of around 2000 or more. However, the minute you pop-up the flash or turn your 430 on, the camera resets the speed to 200 because this is the fastest speed that will normally sync with a flash and the camera prevents you from using a higher one in Av. So instead of exposing the background at f/2.8 - 1/2000, you are overexposing it at f/2.8 - 1/200. Two solutions: Use an aperture small enough to bring the background exposure down to 200 or less, or - if you don't want all that DOF - set your 430 EX to High Speed Sync and shoot in M with an exposure appropriate to the background.

[joruiz]

This is what is probably happening. First, I assume you mean Av mode, not Ae. When you set f/2.8 and measure the bright outdoors background you get a shutter speed of around 2000 or more. However, the minute you pop-up the flash or turn your 430 on, the camera resets the speed to 200 because this is the fastest speed that will normally sync with a flash and the camera prevents you from using a higher one in Av. So instead of exposing the background at f/2.8 - 1/2000, you are overexposing it at f/2.8 - 1/200. Two solutions: Use an aperture small enough to bring the background exposure down to 200 or less, or - if you don't want all that DOF - set your 430 EX to High Speed Sync and shoot in M with an exposure appropriate to the background.


Thanks for the answer, yes Av... my mistake. Actually I had High Spped Sync enabled. I guess I should be shooting in M then, right? no Av? I will try that, of course it should work, but I was hoping I could do this in Av, so the camera would choose the speed for itself and I would fill the subject with the flash.

Thanks again, I need to make more tests.

[Choderboy]

First , practice on non living subjects :)What metering mode were you using? That will make a big difference.

[joruiz]

Hello Dave.. yep, I will practice with an object. Actually I tried with the three metering modes available in my XTi. Wish it had spot metering too.