Canon 430 & 580 Flash Question

Last December I finally made the switch from my Minolta film camera to the Canon XSi. At that time I purchased the Canon 430 flash and initially used the camera in program mode. I did try a couple of shots in the aperture mode and got a flash and an extended shutter time resulting in blurred pictures. At the time I just switched back to program and forgot about it thinking that the flash just lacked the power that my Minolta flashes had. I recently got to try the 580 and found that it too works great in program, but when you switch to aperture mode it had long shutter times. I figured that I was just missing something somewhere and today have reread the manuals for both the camera and the flash. The flash booklet does talk about aperture mode and says “The camera will then automatically set the shutter speed matching the aperture to obtain a standard exposure.” So, my assumption is that the camera is saying that it needs an X shutter speed to get the picture (without the flash), which if that is the case why have the flash. The flash does go off, but unlike my film camera the flash duration is not being relayed to the camera so that it knows that it is a flash picture, not a natural light picture.

I was just taking a picture of the couch in the living room – about four feet away, some natural light coming into the room (not night or anywhere near dark), aperture set for 8, flash set for E-TTL, and when the shutter button is pushed I get a flash and about a second exposure. I did have it set up on a tripod and the picture looked fine, but had it been the grandkids (who move) they would have been a blur.

So my assumption now is that either I have missed something in the several readings of the manuals or that the digital camera does not have the ability that my film camera does when it comes to being able to set the aperture and having the flash/camera work together to take a decent exposure at something like 1/60 of a second.

What am I missing or is this just the way it is (read that as don’t take aperture pictures with the flash turned on.)

Thanks,

Jerry

In Av mode, the camera does NOT take into account the flash being used. So if you are indoors in low light, do NOT use Av mode. Outdoors using the flash as fill, Av should work ok.

Indoors, to start you can use P mode. This sets the shutter speed to ~1/60 when the flash is turned on. Your best bet is M mode on the camera. That way you can control the shutter speed, ISO, and aperture. Since the flash should provide enough light for you, you can set the shutter to 1/200s, ISO to 200, aperture to whatever DOF you want, and fire away. The flash (via ETTL) will fire enough power to light up your subject.
Use FEC (flash exposure compensation) to control the flash output.

Good luck!

Like egordon said. In av mode the camera tries to expose for the existing ambient and then fills the flash in. That can mean excessively slow shutter speeds. Your best bet is to go manual camera, ettl on the flash. Pick a shutter speed between minimum handheld and 1/250 (max sync speed) and then set your aperture for creative reasons. The flash will then adjust power to make up the difference. The slower the shutter speed the more ambient light you get, the faster the less.

Newer cameras like the 50D allows you to limit the elongation of the exposure time when using Av mode to no slower than 1/60, or lock it at 1/250 (shortest sync speed).
I'm not sure if the simpler 450D has that same option, although I do know it doesn't synchronize at any shorter time than 1/200 s.

apersson850 wrote in post #8488993
Newer cameras like the 50D allows you to limit the elongation of the exposure time when using Av mode to no slower than 1/60, or lock it at 1/250 (shortest sync speed).
I'm not sure if the simpler 450D has that same option, although I do know it doesn't synchronize at any shorter time than 1/200 s.

Could you please explain how to limit the shutter in Av mode on 50D?

Since you are worried about shutter speed, use Tv and set the shutter for what you want and the camera will set aperture according. Even on my old 20D I cound set it at 1/320 for indoor sports and get a good pix. you need to enable high speed sync on the flash though.

I just wanter to say thanks for the replies.

Jerry

Green Li wrote in post #8489683
Could you please explain how to limit the shutter in Av mode on 50D?

There's a custom function for that (right now I don't know the number of it).
On older cameras, like my 40D, you could either lock the shutter speed to shortest flash sync speed, when using a flash, or be free-running, just like it is when there is no flash involved.
The 50D also supports the intermediate solution of allowing you to limit it within the handholdable region of 1/60-1/250 s.

Here's another vote for manual on the camera. That flash/camera will figure out what it has to do and do it - at least within its power. Just set what you think you need, up to the max sync speed of the camera, an f-stop in the f5.6 - f8.0 range, ISO about 200, and flash in ETTL mode. That should be a good starting point for indoor flash.

apersson850 wrote in post #8493048
There's a custom function for that (right now I don't know the number of it).
On older cameras, like my 40D, you could either lock the shutter speed to shortest flash sync speed, when using a flash, or be free-running, just like it is when there is no flash involved.
The 50D also supports the intermediate solution of allowing you to limit it within the handholdable region of 1/60-1/250 s.

Great! That's exactly what I wanted to know. It's useful to be able to stay "within the handholdable". Thanks.

THANK YOU - THANK YOU - THANK YOU

I switched over to a 50D about 6 months ago and tonight was my first need to use a flash for true indoor needs. I thought I was going go nuts trying to figure out why at Av 2.8 and ISO320 it (camera) was picking 1 sec exposures! Especially when in P mode it was picking Av3.5 and Tv60 with same ISO. My head really started spinning when I saw the Tv priority exposure settings.

Now it all makes sense (ya, ya, call me the slow one) - of course you wouldn't want the exposure settings to come from the flash.

What would be a cool feature is to set the power of the flash fixed say 1/4 and have the the camera set the Tv based Av and Av base on Tv for a given ISO....um... I guess that would be hard; as the exposure calculation would have to take place during the flash so .... Never mind that won't work. But you could measure the distance to the subject and use a look-up table to determine calculated reflected light based upon aperture. Then when the aperture is set in Av mode, the camera can look up the reflected light of the flashed based upon the setting and use it in conjunction with the existing light to complete the exposure calculations. This would fix the flash compontent of temperation while allowing the other components of temperature to vary based on exposure...

Anyway, thanks - oh yea the function is C.FN1 and the choices are auto (default - camera sets based on existing light, auto 1/250-1/60 and fixed 1/60th

not_keith wrote in post #8596586
What would be a cool feature is to set the power of the flash fixed say 1/4 and have the the camera set the Tv based Av and Av base on Tv for a given ISO....um... I guess that would be hard; as the exposure calculation would have to take place during the flash so .... Never mind that won't work. But you could measure the distance to the subject and use a look-up table to determine calculated reflected light based upon aperture. Then when the aperture is set in Av mode, the camera can look up the reflected light of the flashed based upon the setting and use it in conjunction with the existing light to complete the exposure calculations. This would fix the flash compontent of temperation while allowing the other components of temperature to vary based on exposure...

Keith, I don't see any need for what you're suggesting. The usual procedure is to work in manual, and set the camera to expose the background however you like - whatever iso/aperture/shutter speed you want. You should stay below your cameras flash sync speed though, which is 1/250th with a 50D. You then use the flash in ETTL to automatically expose the main subject, using FEC to tweak the amount of light the flash puts out, judging using your histogram. This all takes very little time once you understand what's going on and you're used to your equipment.

Doesn't that pretty much loose the 'TTL' capabilities of the flash - so why buy a Canon flash. A YN640 or a Vivitar 285 might be better choices under those circumstances.

josh5k wrote in post #8600088
Doesn't that pretty much loose the 'TTL' capabilities of the flash - so why buy a Canon flash. A YN640 or a Vivitar 285 might be better choices under those circumstances.

No, he is saying use manual mode on the camera, and use ETTL(auto) on the flash.

That is the way most experienced photographers do it.

Manual camera and auto flash is the way everyone should do it, at least until you reach a fairly good level of competency with flash.