Using Flash Correctly? 580ex and 40D.

nutsnbolts wrote in post #7430998
Ok, these are great things and lots to absorb. To simplify and play around with my settings, what i did was put it on ETTL and Manual mode. I then dialed my shutter speed to 1/60th or higher. I noticed that my meter was all the way far left. Do I still worry about the meter?

No, forget the meter. The little meter in the VF is telling you what the camera thinks of your settings for ambient only. The meter does not anticipate the flash in any way. If you want the flash to be the main source of light in the shot then the meter will always be off the left side.

This is also why the camera performs so 'strangely' in Av and Tv modes with the flash mounted. Av and Tv always pick the dependent variable to properly expose the shot for ambient light. They will not deliberately underexpose ambient just because you turn on the flash.

JeffreyG wrote in post #7431019
No, forget the meter. The little meter in the VF is telling you what the camera thinks of your settings for ambient only. The meter does not anticipate the flash in any way. If you want the flash to be the main source of light in the shot then the meter will always be off the left side.

This is also why the camera performs so 'strangely' in Av and Tv modes with the flash mounted. Av and Tv always pick the dependent variable to properly expose the shot for ambient light. They will not deliberately underexpose ambient just because you turn on the flash.

Ahh great! I did take a few shots which looked fine but really, I don't know if it's fine or not. It looked good but how do you know when to push the ISO higher or specifically which shutter speed to go with other than the fact that you should go higher than 1/60th of a second.

I try to stick with the rule of ISO 100 and work from there. But based on everyone's response, there seems to be a play between going higher with ISO and so forth.

Once you decide to light a scene with flash (and only flash) then settings actually become easy.

Shutter speed = set to the maximum sych speed.
Aperture = Set for the DOF you want
ISO = Set high enough that the flash does not run out of power trying to light the scene. Basically, if you take a shot and it is underexposed then you need to increase ISO.

Note that the 'reach' of your flash is 100% dependent on the ISO and aperture and shutter speed has no effect. Underexposure in E-TTL mode with flash that cannot be improved by +FEC indicates lack of flash power. Open up the aperture or increase the ISO or both.

flash on ettl ...camera on 5.6, 30th, iso 400...bounce off the ceiling...

JeffreyG wrote in post #7434471
Once you decide to light a scene with flash (and only flash) then settings actually become easy.

Shutter speed = set to the maximum sych speed.
Aperture = Set for the DOF you want
ISO = Set high enough that the flash does not run out of power trying to light the scene. Basically, if you take a shot and it is underexposed then you need to increase ISO.

Note that the 'reach' of your flash is 100% dependent on the ISO and aperture and shutter speed has no effect. Underexposure in E-TTL mode with flash that cannot be improved by +FEC indicates lack of flash power. Open up the aperture or increase the ISO or both.

Can you elaborate on set to maximum sync speed?

Read the EOS Bible.

tim wrote in post #7435799
Read the EOS Bible.

+100000...

https://photography-on-the.net/forum/showthre​ad.php?t=138907

nutsnbolts wrote in post #7213833
Ok, I'm having a hard time with this.

I attach the flash (580Ex) to the 40D, leave the settings to ETTL and shoot away on AP mode.

I try to do bounce flash to the ceiling but can't get the Shutter speed faster than 1/10 of a second if I'm lucky.

What am I supposed to expect with these settings? Is this correct?

In addition, I am using a 17-55, f/2.8 and even tried it with the 50mm f/1.8 and still I'm having a hard time with low light conditions.

Please help.

Thanks.

When shooting with flash always shoot in manual mode.. Exposure is much more easy to control..

nutsnbolts wrote in post #7213833
Ok, I'm having a hard time with this.

I attach the flash (580Ex) to the 40D, leave the settings to ETTL and shoot away on AP mode.

I try to do bounce flash to the ceiling but can't get the Shutter speed faster than 1/10 of a second if I'm lucky.

What am I supposed to expect with these settings? Is this correct?

In addition, I am using a 17-55, f/2.8 and even tried it with the 50mm f/1.8 and still I'm having a hard time with low light conditions.

Please help.

Thanks.

In Av mode, the meter will set the shutter speed to a slow speed in low light, in an attempt to use the ambient light in the photo. Separately the ETTL flash metering sets the light output for the flash. The camera is simply trying to give you a reasonable exposure assuming no flash, and in your low light the meter says it needs 1/10 for the selected aperture.