Fill Flash - question - please help me understand

I have been reading topics on fill-flash and consensus is to use either Manual or Av mode. Manual mode is preferred choice because it give you more control on balancing the ambient light (via shutter) vs flash light (via aperture). In Manual mode, you set the Av based on DOF you want and change the shutter as needed to control the ambient light.

What I don't understand is why Av mode is not better than Manual mode? Instead of choosing shutter it lets to set the shutter for you. Let's say when photographing wedding in a huge hall and ambient light is not changing very much. Based on the ambient light you decide to have +1 stop exposure. So in Av mode to set +1 EC using +/- button and aperture you want and forget about shutter speed. In Manual mode every time you take the shot you have you have to adjust the shutter to make sure the needle is +1 EC. What's very inconvienent?

I know I am missing something and need to know what.

You are missing something. The camera is measuring/metering reflected light, not incident (ambient) light, and ignoring flash for a moment, is as susceptible to getting the exposure wrong as it is in any other circumstances. Aim the camera at the bride and the white dress will cause underexposure. Catch some backlighting from a disco light, wall light or daylit window and the camera will underexpose again. Aim at the groom against a dark wall and the camera will overexpose massively.

Now turn on the flash and you have the problematic ambient exposure to deal with, from Av mode, plus ETTL flash adding in its own surprises. So that's two writhing snakes to control instead of only one. If you lock down the ambient exposure by shooting in manual your camera will not be fooled by any variations in reflectivity. Meter for slight undereposure of the ambient and then let the (bounced) flash light your subject and top off the shortfall in the room. At least then you will only have FEC to juggle with and not EC and FEC at the same time. You will also remain in control of shutter speed, so will not get any nasty surprises if/when the camera would otherwise decide that 1/30 would be a nice speed for the ambient conditions.

Have a read here - http://www.planetneil.​com …h-photography-techniques/

I wonder where you're getting your information.

In Av mode the camera's exposing for ambient, the flash works as fill. You can still put too much flash power in if you're not careful, but I think the camera assumes it's only fill.

In manual mode the flash is the main light. Ambient exposure is calculated, but flash is main. Turn the FEC down to -1 or -2 if you want the flash as fill.

For real control put everything in manual, but if things change quickly you'd better be quick on those buttons.

In a huge hall with reasonably steady but low light i'd be shooting manual, but the flash would be the main light. Honestly the off camera flash triggered by radio would be the main light, but same deal with on camera flash. On camera it'd be ETTL with FEC+1, off camera it's be manual of course.

What is it you're trying to achieve? Anything in particular or just understanding? Understanding takes time and experience, it's not really something that you can be given simple instructions to so you can follow without thought.

teamplayer wrote in post #8154195
In Manual mode every time you take the shot you have you have to adjust the shutter to make sure the needle is +1 EC. What's very inconvienent?

Why?

shutter speed? flash?

might be good idea if you get some information on how to use flash

tdodd wrote in post #8158037
[Snip]

Have a read here - [URL][URL]http://www.p​lanetneil.com/tangents​/flash-photography-techniques/[/url]

I'll second this... read it and be prepared to be amazed!

Anyone can take a picture with a point a shoot, but not anyone can go buy a DSLR and shoot a wedding right after buying it (without understanding Shutter Speed, Aperture, and ISO...among hundreds of other things) I met a person who was going to shoot her first wedding..I asked her about aperture, and she did NOT know what it was....sometimes I think that anybody can shoot a wedding without experience...does this bother anyone else????

No offense "Team Player"