580EX and Raw

[blu82]

Please help me to understand. I take 95% of my shots in Av or Tv modes with a 20D. I bought a 580EX and for its first use tried a few shots in low light indoors. In Av mode at about f11 the camera calculated that I would need a 10 second exposure. Why is it telling me there is not enough light when I have a flash?

The only time it appears to work is in P or Auto modes. Page 12 of its manual almost makes sense.

[Jon]

In Av mode, the camera meters for the available light so the background will be properly exposed, then uses the flash to light the subject. There's more on this in the EOS Flash Sticky (http://photography-on-the.net/forum/showthread.php?t=46599). In P and the Basic modes, the flash is presumed to be the primary, or only, light source.

[blu82]

Thank you Jon

So does that mean I now can not take indoor RAW pictures in Av mode with a flash?
I have to remove the flash indoors to get RAW images?
Thanks
Dave

[pierrot]

Why on earth do you care of RAW? The file format has nothing to see with the shooting mode.
Yes you can take RAW or JPEG, indoors or outdoors, whatever the Av or Tv mode, with or without flash. There is no conexion between the file/image format and the shhoting mode.

[robertwgross]

Why on earth do you care of RAW? The file format has nothing to see with the shooting mode.
Yes you can take RAW or JPEG, indoors or outdoors, whatever the Av or Tv mode, with or without flash. There is no conexion between the file/image format and the shhoting mode.

This comment is just plain gibberish.

The 20D will not shoot RAW files in the basic modes. It will shoot RAW or JPEG in the creative modes such as Av or Tv, but it will do that whether or not you use internal flash, external flash, or no flash at all.

---Bob Gross---

[megaweb]

Use M mode with settings like f5.6 to f8, speed 1/30sec to 1/60sec (wide) or faster (tele)and 580ex will take care the rest.

[tim]

Use M mode with settings like f5.6 to f8, speed 1/30sec to 1/60sec (wide) or faster (tele)and 580ex will take care the rest.

Agreed, M mode is best if your primary light source is the flash. Av/Tv/P are best if you're using the flash as fill. Set the shutter speed to expose the background how you want it, I often go up to 1/250th because I don't care about the background, just the foreground. If your main subject is illuminated at all try to keep the shutter speed up a bit, otherwise if they move after the shot you could end up with "ghosting" around them.

Set the aperture to whatever you like, the flash brightness will be set so it exposes the subject properly. If you use F22 a 580EX might not be bright enough, but short of that you should be fine. Use FEC if the flash makes the subject a little too brighter or darker than you want.

[pierrot]

The 20D will not shoot RAW files in the basic modes. It will shoot RAW or JPEG in the creative modes such as Av or Tv, but it will do that whether or not you use internal flash, external flash, or no flash at all.
Sorry for my gibberish Bob, I'm just a poor foreigner...
We give the same information but your formulation is much better than mine. :mrgreen:

[blu82]

Thank you very much everyone especially Megaweb for concise effortless accurate response. Even replies with a touch of shirtyness help me to see how easy it is to understand.

Thank you all, I've got it.

[jfred]

there's a custom function you can use to force the flash shutter speed to 1/250th in Av mode, which (intially!) made the 20D feel like it worked "just the same" as my old canon SLR

My first few shots with the 580ex made me think I'd been conned. Having played with it some more, I now love it to pieces.

[tim]

there's a custom function you can use to force the flash shutter speed to 1/250th in Av mode, which (intially!) made the 20D feel like it worked "just the same" as my old canon SLR

What's that CF useful for?

[MAD DOG]

Tim,

Gald you posted.

I haven't had much experience of using flash (I have a 550EX, which I have only recently aquired).
Your advice goes a long way to point me in the right direction, I had also done something very similar to blu82 using Av mode.

I will have a play tonight and try it in manual as you have suggested.

MANY THANKS from a newbie

[tim]

You're more than welcome, we're all new at some point, I like to pay it forward.

[robertwgross]

Sorry for my gibberish Bob, I'm just a poor foreigner...
We give the same information but your formulation is much better than mine. :mrgreen:

Actually, your comment was just plain incorrect, and it was not a language problem. That makes it very misleading to some readers.

---Bob Gross---