Totally Newbie Question

[**luvmygirlz**]

Ok, I'm sure I'll get laughed out of here, but I'm still new at this, and there's something I can't figure out. How do chose the correct manual settings when using a flash? I usually set my AV and then let the meter guide me to correct shutter speed, but how can tge meter predict what the flash output will be? I can't wven use AV mode, because it automatically chooses a very low ss to compensate for the low light. What am I missing here??

[jwwill0]

The camera will automatically compensate for the flash. It uses the E-TTL II metering that you have heard about on the camera. When you press the shutter release, the camera actually fires two flashes. I measures the output from the first and meters the scene, then fires the second flash and opens the shutter.

The reason Av doesn't work is that it is set for fill flash by default. The camera will meter the scene as if the flash wasn't there, then will fire the flash to illuminate the foreground. There is a custom feature that you can change if you don't like this setting.

With a flash, you should probably use either the P mode or full Manual mode. In manual, you can pretty much set the shutter speed and aperature to whatever you want, and the camera will try to adjust the flash output to the right amount. You can try this out by taking some pictures in manual mode. Change several settings and you will likely still get a picture that looks about the same. You can use flash compensation to increase or decrease the flash output.

[tim]

When the flash is the main light you need to be in manual mode on the camera. ETTL will automatically expose the subject correctly, but it's not perfect. Reflective and white/black objects can fool it - the solutions are bouncing the flash and positive/negative flash exposure compensation respectively.

In Av the flash is acting as fill only.

(edit - jw beat me to it!)

[SuzyView]

Funny how you both said the same thing differently. :)

[entrefoto]

I was actually wondering the exact same thing! I love shooting in Av and i'm glad i read this thread before shooting my first (free) wedding this weekend. Thanks for the thread!

[jwwill0]

Yep, but tim has 12,231 more posts than me!! So, I defer.

[tim]

Yeah but i've written the same thing dozens of times, so I no longer go into quite as much detail as you did :)

[**luvmygirlz**]

Thanks for clarifying things for me!:)

[SuzyView]

My son, the other day, saw that Tim has over 12000 posts. He asked me if he talked a lot. I said Tim joined in Nov 2004. I joined Oct 2005 and I have 2800 already. He said, "Mom, we all know you talk too much." Kids. Keep posting, Tim. You are one of the wedding photographers here that makes me want to improve my skills so I can post something interesting for once. :) :(

[tim]

Thanks Suzy :) I have to spend more time on photography and less on POTN... then I might get a few more things done!

[Alvy]

It's amazing just how long I've gone wondering how the hell I get the light metering on the flash at gigs and so on, to work properly, to suddenly read this post and realise what an idiot I've been all along, by shooting in Av mode :D

Still, better late than never :)

[SYS]

In manual, you can pretty much set the shutter speed and aperature to whatever you want, and the camera will try to adjust the flash output to the right amount.

Actually I was wondering about this very thing. When I use the manual mode in the dark with my 580ex and needed to set the shutter speed to, let's say, 200, and the aperture to, let's say, 5.6, the exposure level indicator displays that my exposure is totally off. It is my understanding that, when using the flash, I should just ignore the indicator and allow the camera to automatically adjust my desired manual setting for me. Am I correct or wrong?

[davidwhatley]

Actually I was wondering about this very thing. When I use the manual mode in the dark with my 580ex and needed to set the shutter speed to, let's say, 200, and the aperture to, let's say, 5.6, the exposure level indicator displays that my exposure is totally off. It is my understanding that, when using the flash, I should just ignore the indicator and allow the camera to automatically adjust my desired manual setting for me. Am I correct or wrong?

You will need to adjust the ISO if you want to have both the shutter speed and aperture set to you "preference". There will be XX amount of light to expose, there for the ISO is important.

[SYS]

You will need to adjust the ISO if you want to have both the shutter speed and aperture set to you "preference". There will be XX amount of light to expose, there for the ISO is important.

I do adjust the ISO all the time when I'm not using the flash, but when using the flash, is there an indicator that tells you which ISO that I should be using that tells me that I'm getting the right exposure?

[jwwill0]

Sys, you are somewhat correct that you can ignore the in-camera metering in Manual with flash and still get a reasonable exposure (most of the time). The 580EX will blast out quite a bit of light. The camera is metering based off of available light only, and is not compensating for the flash (use P mode for this). You can still use the in camera meter as a guide to determine how much natural light you want to include in the exposure. If you only want flash light to show up, then make sure the in-camera meter shows that it is off-the-chart underexposed. If you were to take a picture like this without the flash on, it would be totally black. If you want to include some available light, then you must pay attention to the metering. The flash has nothing to do with how much available light you let in. That is totally controlled by shutter speed, aperature, and ISO.

If you are in total darkness, then the aperature and ISO will determine what kind of range you can get from your flash. If you have a close subject, you can do about anything. If you start getting a little farther away, you may have to open up the aperature or increase the ISO to get enough light from the flash to reach the subject.

[SYS]

Sys, you are somewhat correct that you can ignore the in-camera metering in Manual with flash and still get a reasonable exposure (most of the time). The 580EX will blast out quite a bit of light. The camera is metering based off of available light only, and is not compensating for the flash (use P mode for this). You can still use the in camera meter as a guide to determine how much natural light you want to include in the exposure. If you only want flash light to show up, then make sure the in-camera meter shows that it is off-the-chart underexposed. If you were to take a picture like this without the flash on, it would be totally black. If you want to include some available light, then you must pay attention to the metering. The flash has nothing to do with how much available light you let in. That is totally controlled by shutter speed, aperature, and ISO.

If you are in total darkness, then the aperature and ISO will determine what kind of range you can get from your flash. If you have a close subject, you can do about anything. If you start getting a little farther away, you may have to open up the aperature or increase the ISO to get enough light from the flash to reach the subject.

Thank you for the explanation. This is very helpful!!