help with flash and background exposure

[learjet035]

With help from everyone here I greatly improved my indoor natural light shots. Thanks! Now I need your help again with these type of shots. I shot both 1 right after the other in AV mode. On the second one I popped the flash. How can I get the background to show up also? Any other input would be great. I know I can use levels in PS, I just wanted you too see what came out of the camera. Thanks again.

[rent]

please post exif with shooting mode information. flash exposure depends on a lot of variables.

however, for the scenario appeared in your picture (bright background, dark foreground), my approach would be:

1) set your exposure to correctly expose the background. an easy way to do that would be just to meter the background without the people in the picture first. let's say it'll turn out to be something like f16, 1/100 @ ISO100.

2) now you can then set this exposure manually using M mode (or lock your exposure), pop up the flash and shoot with the people in the picture.

3) you may need to adjust flash exposure compensation, or turn off auto-flash reduction. i'm not sure if these functions are available on the XT though.

good luck!

-alex

[learjet035]

Thanks Rent-
1st- 1/800 s @ f/3.5 Auto exposure AV 100 iso 50mm flash did not fire- Pattern=metering
2nd- 1/200 s @f/3.5 Auto exposure 100iso 50mm flash fired(compulsory???) Pattern=metering
I think I remember reading about flash compensation, but I am a total newb so I have no idea how to go about doing that.
PS. Is there an easier way to post the data without just retyping it?

[kawter2]

Thanks Rent-
1st- 1/800 s @ f/3.5 Auto exposure AV 100 iso 50mm flash did not fire- Pattern=metering
2nd- 1/200 s @f/3.5 Auto exposure 100iso 50mm flash fired(compulsory???) Pattern=metering
I think I remember reading about flash compensation, but I am a total newb so I have no idea how to go about doing that.
PS. Is there an easier way to post the data without just retyping it?


This is a flash sync issue, your internal fhash sync limited the shutter speed to 1/200 Your meter would have told you that you were about to overexpose when you shot the pic. next time w/a internal flash (i.e. flash with no "high-speed" mode) you need to bump up your apreture to a pont that will allow the scene to be properly exposed

[learjet035]

Thank you for the advice, so what you are saying is that I should have moved my aperature to a higher setting? IE 5 or 6? Still confused

[rent]

you camera has a top shutter speed at which the flash will work (x-sync speed). for the XT it is 1/200.

for the second picture, since you are using flash, the camera limited your shutter speed to 1/200. since the f-value remained the same (f3.5), your second picture was overexposed by 2 stops (exposure time increased from 1/800 to 1/200).

your second picture would have come out the way you liked with background nicely exposed if you had taken it at 1/200 @ f7.3 (note this is the same exposure value as 1/800 @ f3.5) with your flash firing. the flash's E-TTL capability would have correctly exposed your foreground subjects by cutting off the flash light at the appropriate time. since your flash does not affect the background, the background exposure would remain the same as your first picture.

hope this helps.

-alex

Thanks Rent-
1st- 1/800 s @ f/3.5 Auto exposure AV 100 iso 50mm flash did not fire- Pattern=metering
2nd- 1/200 s @f/3.5 Auto exposure 100iso 50mm flash fired(compulsory???) Pattern=metering
I think I remember reading about flash compensation, but I am a total newb so I have no idea how to go about doing that.
PS. Is there an easier way to post the data without just retyping it?

[tim]

Were you in Av for that 2nd shot? I can't follow your post above, maybe because i'm tired. In this case i'd use Av mode on evaluative metering with the flash popped up, F4-F8, ISO 200-400. Anything in that range should expose the background and the flash should expose the foreground fine.

[kawter2]

F4-F8, ISO 200-400. Anything in that range should expose the background and the flash should expose the foreground fine.

He shot f3.5 & 1/200 @ ISO 100. That would blow out any normal day

[learjet035]

So much to learn. =) Thank you all for the input. Yes- 2nd shot was also in AV mode. I understand now what happened inside the camera to cause the 2 different results. I selected 3.5 to get some good DOF, but I didn't think of the amount of light that would allow in. I guess my next question would be, is there a quick "safe" setting for those point and shoot shots that don't have to be perfect but will expose pretty good with a similar backlight issue? If I shoot in full auto I won't get a flash, so I'm guessing no to that. If I use the "P" mode with Evalu metering and a flash would I have a better chance?

[chtgrubbs]

The fundamental rule to remember when mixing flash with ambient light is:

Flash exposure is determined by the aperture. Background exposure is determined by the shutter speed selected to use with the flash aperture.