Canon Av mode shutter speed with flash

number41

number41

number41

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On the 20D most of my shooting is done in the Av mode. I've read in places that in Av mode the flash makes no difference to the shutter speed - ie when in Av mode even with the flash on the shutter speed stays the same. That is indeed the case.

Just wondering how other people deal with it? I'm not confident enough to go full manual yet and dont like P mode. I also like to edit RAW images and in the fully auto mode it doesnt take RAW!! I'm off to shoot some break dancing in a club soon and as the room will be dark, using Av mode is not an option as even with the flash the exposures are too long :(

Why did Canon do this? I'm looking to get the 430EX next month and was wondering if this is the same for the external flash? Can you use auto flash mode with the Av setting if you use an external flash?

I understand why there is an option to use the flash in that way, but I wish you could choose between the two different settings in the Av and Tv mode for fast moving shots. Portraits, etc are fine, but if the subject moves Av mode's slow shutter ruins it :(
 
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Does the 20D have custom functions?

On my 350D there is an option for when you are shooting in AV mode with the flash to always set the shutter speed to 1/200th, so you might want to see if your camera has something similar.
 
Ahh interesting. Did you hack the firmware for the 350D as I think there was a hack for it to do that? Anyone have a 20D and know if this is possible?
 
Canon ETTL intimidates people until they work out how it actually works.

If you shoot in Tv or Av the camera will meter for ambient light and use the flash for fill only. So if you're outside in the shade for example or you need a bit of fill, stick it Av, pick the appropriate aperture for the DOF you want and away you go.

If you shoot in M however the camera will take the shot at the aperture and shutter speed you want and will vary the flash accordingly to get the right exposure. So in a pitch black room you can dial in a sensible exposure (1/100@f/8, ISO400 for example) and the camera will have a decent go at giving you a normal exposure. Obviously an external flash will allow you to get more illumination, better cycle times etc.

The bottom line is if you want to use flash then use M mode, it's not as scary as using M mode in daylight because with a flash you've got a variable power light source so while you can still make mistakes it's not as hard as it seems. There is, of course, no substitute for practice.
 
number41 said:
Ahh interesting. Did you hack the firmware for the 350D as I think there was a hack for it to do that? Anyone have a 20D and know if this is possible?
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Nah it's always had that option.

A quick Google suggests the 20D also does.

In your camera settings, go in the custom functions and find "03: Flash Sync in Av Mode." and set it to "1"

It should lock the shutter at 1/250 when shooting in AV mode with flash.
 
Thanks for the advice stewart. Do you reckon ISO 800, F2.8 with a 1/200 shutter speed will be enough to capture the action?

Cheers Jotun! I have the manual in front of me and it doesnt mention that setting in the Av page, but skipping to the custom funtion page reveals all! Option 3 it is indeed!!
 
number41 said:
Thanks for the advice stewart. Do you reckon ISO 800, F2.8 with a 1/200 shutter speed will be enough to capture the action?
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You don't need to use ISO800 or F2.8 but doing so will mean the flash won't have to fire as strong.
Try 1/200, F4, ISO 400 to start with :)

Your main problem will be focusing in such dark conditions.
 
AdWright said:
...which is helped by the speedlites emitting a red focus pattern.
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Have you tried it in a very dark room ;)
I've done a few weddings at Combe Abbey in the Medieval Suite which is lit only by candles. My Canon 580EX, 24-70L , 100mm F2.8 and skills were really tested. The focus pattern didn't help much at all; from my experience it's use is limited to indoor house lighting only.
 
AdWright said:
...which is helped by the speedlites emitting a red focus pattern. Go on, number41, buy the 430ex... :)
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God damn the internet! I've been looking at flash photography guides and can see that an external flash can make a huuuge difference! Now I dont want to shoot photographs using the in-built flash! Decided to pop into town tmrw and check out the 430ex and go to just watch the break dancing with beer instead. Will do the photo part next time :D
 
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