Shutter Speed aka. Why are all my pictures blurry now?

lungdoc wrote in post #4281209
I don't know if I follow you here. The EOS flash system by default uses flash as fill in Av and main light source in P. The custom function simply forces the shutter speed to 1/250 in Av, I don't think it changes the flash behaviour - in fact I believe you'd get less flash output say in a situation where without flash Av exposure is 1/320 at f/8; with this function enabled you'd be overexposing at 1/200 even before you added the flash. Now in darker situations where pre-flash SS is slower than 1/250 (say it was 1/125) then I suppose it does turn flash into main lighting with darker backgrounds. I don't really understand the advantage of this function since you already have P mode with flash acting as main light; M for full control - seems to me that leaving Av mode with flash as fill has a big advantage. Main Av drawback is you need to remember that it is fill AND unless you use high speed sync you'll overexpose in bright light (and can't use onboard flash for fill in bright light).

First off, I'm speaking of my hacked 300D and more modern Canons may be different. Don't think so, but maybe.

As you know, if the flash is the sole light source the shutter speed has no effect on exposure - the flash intensity and duration, aperture and ISO are the only factors involved in exposure.

Absent the high-speed flash option in high-end flash units, the highest shutter speed that can be successfully used with flash on my 300D is 1/200 second.

If I set CF 3-1, shutter speed in Av mode is forced to 1/200 whenever flash is used, while CF 3-0 allows the light meter to set shutter speed, just as it does in P.

I normally use CF3-1, so when I want the flash to be the primary light source I select Av and set aperture as required. If I want some fill light I'll choose P and let the meter select shutter speed and aperture.

Example:

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In P mode with flash in XXd cameras the shutter speed is set to 1/60 and flash determines exposure.

lungdoc wrote in post #4284914
In P mode with flash in XXd cameras the shutter speed is set to 1/60 and flash determines exposure.

Really? Isn't that a little strange?

My ancient 300D (in P mode) selects shutter speeds between 1/60 and 1/200.

-js

Sorry - I probably oversimplified since I usually use flash either in darkness enough so SS with ambient would be below 1/60 or bright light outdoors so it would be higher than sync speed. Per the flash forum FAQ:

"Flash fact #4: Your camera measures ambient light and flash illumination separately. In Av, Tv or P modes, it will attempt to expose properly for the ambient light by adjusting either the shutter speed, aperture, or both. The fact that you have your flash turned on has no effect on this** ( one exception is that in P mode it will not use a shutter speed slower than 1/60 with flash). The camera’s metering system cannot predict how much illumination will be gained by the flash, so it doesn’t try. In manual mode, the meter in the viewfinder measures only ambient light, because that’s all it has to measure."

Therefore in usual dark indoor flash settings P will default to 1/60 while Av will use slower shutter speeds attempting to get ambient exposure right. In P shutter speed varies between 1/60 and Xsync speed.

lungdoc wrote in post #4285020
Therefore in usual dark indoor flash settings P will default to 1/60 while Av will use slower shutter speeds attempting to get ambient exposure right.

If you force 1/200 in AV mode then what does it do to get the exposure right?

number six wrote in post #4284868
Actually, with CF 3-1, Av mode functions as M mode with the shutter preset to 1/200.

But it shows as a perfect exposure in AV mode if 3-1 set. and shows as far far under exposed in M

KIPAX wrote in post #4285135
If you force 1/200 in AV mode then what does it do to get the exposure right?

In that case I believe it simply puts out enough flash for correct exposure, essentially using flash as main lighting (same as M with 1/200 and chosen aperture). I believe it can also lead to overexposure in outdoor settings where 1/200 is too slow for chosen aperture and ISO. I avoid it since I like to think of flash with Av as "always fill".

KIPAX wrote in post #4285135
If you force 1/200 in AV mode then what does it do to get the exposure right?

The E-TTL flash adjusts its output for the right exposure.

-js

i think the problem is, the shutter speed is to low, if you want to get all the details properly, is it external flash needed?

number six wrote in post #4285432
The E-TTL flash adjusts its output for the right exposure.

-js

I hoped that was the answer but in M it doesn't ?

KIPAX wrote in post #4285521
I hoped that was the answer but in M it doesn't?

It does the same thing in M. These are new shots:

Av, 1/200, f/5.6:

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If you want to get a bit better result with the on-board flash invest in one of these:

http://www.bhphotovide​o.com …Soft_Screen_Dif​fuser.html

Just remember that for indoor shooting the camera exposes for the background while ETTL II controls the flash output to expose the subject.

For taking pictures of a toddler under room light try your camera in MANUAL using ISO 200, f/5.6, 1/160s and the onboard flash. To keep things simple set WB to either flash or AWB.

Good idea. Much more elegant than a hankie over the flash.

-js