20D built in flash problem (maybe)

When using any of the "creative" modes such as Tv, Av, and M, the
camera doesn't seem to be aware when I have the built in flash popped
up. For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Oddly enough, in the auto-modes, the camera is smart enough to pop up
the flash when required.

If I set the flash exposure compensation at +2, there is some
difference, but I don't think that's really the correct approach
anyway.

Can anyone help? The instruction manual implies that with Av mode,
for example, when you pop up the flash, the shutter speed should be
recalculated.

D

"Dave Bowman" wrote:

When using any of the "creative" modes such as Tv, Av, and M, the
camera doesn't seem to be aware when I have the built in flash popped
up.

That's Canon. In creative mode, flash is for fill flash.

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient light
in insufficient.

If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

My understanding was that it should go back to normal Av operation when you
close the flash.

Oddly enough, in the auto-modes, the camera is smart enough to pop up
the flash when required.

That's what auto meansg.

Can anyone help? The instruction manual implies that with Av mode,
for example, when you pop up the flash, the shutter speed should be
recalculated.

Well, exposure (i.e. shutter speed) at the specified f stop should be
recalculated every time you take a shot, unless you enable function 3, at
which point it should be 1/250 whenever the flash is up.

The question here is, does Av mode go back to normal when you close the
flash???

You could just use manual mode and set things the way you want them. My
Rolleiflex doesn't have this problemg.

(Truth in advertising: I own a 300D, not a 20D.)

David J. Littleboy
Tokyo, Japan

"Dave Bowman" wrote:

When using any of the "creative" modes such as Tv, Av, and M, the
camera doesn't seem to be aware when I have the built in flash popped
up.

That's Canon. In creative mode, flash is for fill flash.

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient light
in insufficient.

If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

My understanding was that it should go back to normal Av operation when you
close the flash.

Oddly enough, in the auto-modes, the camera is smart enough to pop up
the flash when required.

That's what auto meansg.

Can anyone help? The instruction manual implies that with Av mode,
for example, when you pop up the flash, the shutter speed should be
recalculated.

Well, exposure (i.e. shutter speed) at the specified f stop should be
recalculated every time you take a shot, unless you enable function 3, at
which point it should be 1/250 whenever the flash is up.

The question here is, does Av mode go back to normal when you close the
flash???

You could just use manual mode and set things the way you want them. My
Rolleiflex doesn't have this problemg.

(Truth in advertising: I own a 300D, not a 20D.)

David J. Littleboy
Tokyo, Japan

On Wed, 22 Sep 2004 14:47:59 +0900, "David J. Littleboy"
wrote:

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient light
in insufficient.

Sure, but you'd expect that all else being equal (aperture), if the
flash is available, the required shutter speed should be faster, this
doesn't appear to be the case.

A slightly more concrete example is my office in the evening. Bright
enough in there to read. Using F8, the shutter speed the camera wants
is 0.8 seconds, pop up the flash, maybe it drops to 0.4 but usually
stays at 0.8. But I know you can take a much faster photo under these
conditions, and certainly in the auto-modes, the camera is smart
enough not to use so slow a shutter speed.


If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

No, it will go back to its original shutter speed. That's what I'd
expect to happen. But when fn 3 is not enabled, there is no change in
the shutter speed in Av mode, that's what is baffling me.


D

On Wed, 22 Sep 2004 14:47:59 +0900, "David J. Littleboy"
wrote:

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient light
in insufficient.

Sure, but you'd expect that all else being equal (aperture), if the
flash is available, the required shutter speed should be faster, this
doesn't appear to be the case.

A slightly more concrete example is my office in the evening. Bright
enough in there to read. Using F8, the shutter speed the camera wants
is 0.8 seconds, pop up the flash, maybe it drops to 0.4 but usually
stays at 0.8. But I know you can take a much faster photo under these
conditions, and certainly in the auto-modes, the camera is smart
enough not to use so slow a shutter speed.


If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

No, it will go back to its original shutter speed. That's what I'd
expect to happen. But when fn 3 is not enabled, there is no change in
the shutter speed in Av mode, that's what is baffling me.


D

"Dave Bowman" wrote:
On Wed, 22 Sep 2004 14:47:59 +0900, "David J. Littleboy"

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient
light
in insufficient.

Sure, but you'd expect that all else being equal (aperture), if the
flash is available, the required shutter speed should be faster, this
doesn't appear to be the case.

No. The _definition_ of fill flash in Av mode is "set the exposure according
to the ambient light and fire the flash". That requires not changing the
shutter speed, since the f stop is fixed.

In other words, it has to use the same shutter speed. (My understanding is
that Av mode on almost every camera ever made works this way.)

A slightly more concrete example is my office in the evening. Bright
enough in there to read. Using F8, the shutter speed the camera wants
is 0.8 seconds, pop up the flash, maybe it drops to 0.4 but usually
stays at 0.8. But I know you can take a much faster photo under these
conditions, and certainly in the auto-modes, the camera is smart
enough not to use so slow a shutter speed.

The way to handle this would be to use regular EV exposure compensation (NOT
flash exposure compensation) to set how much you are willing to underexpose.
Unless you tell the camera how much to underexpose, it can't know.

Again, Av mode + flash is _fill flash mode_. This is a well-defined concept
in photography, and Canon implements this function correctly.

If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

No, it will go back to its original shutter speed. That's what I'd
expect to happen.

Good. You had me worried there for a minute.

But when fn 3 is not enabled, there is no change in
the shutter speed in Av mode, that's what is baffling me.

Av mode is a "creative mode". Creative modes are modes in which you don't
get backstabbed by automagic magic doing the wrong thing. If you want the
parts of the scene not illuminated adequately by the flash to be
underexposed, you have to tell the camera that.

David J. Littleboy
Tokyo, Japan

"Dave Bowman" wrote:
On Wed, 22 Sep 2004 14:47:59 +0900, "David J. Littleboy"

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient
light
in insufficient.

Sure, but you'd expect that all else being equal (aperture), if the
flash is available, the required shutter speed should be faster, this
doesn't appear to be the case.

No. The _definition_ of fill flash in Av mode is "set the exposure according
to the ambient light and fire the flash". That requires not changing the
shutter speed, since the f stop is fixed.

In other words, it has to use the same shutter speed. (My understanding is
that Av mode on almost every camera ever made works this way.)

A slightly more concrete example is my office in the evening. Bright
enough in there to read. Using F8, the shutter speed the camera wants
is 0.8 seconds, pop up the flash, maybe it drops to 0.4 but usually
stays at 0.8. But I know you can take a much faster photo under these
conditions, and certainly in the auto-modes, the camera is smart
enough not to use so slow a shutter speed.

The way to handle this would be to use regular EV exposure compensation (NOT
flash exposure compensation) to set how much you are willing to underexpose.
Unless you tell the camera how much to underexpose, it can't know.

Again, Av mode + flash is _fill flash mode_. This is a well-defined concept
in photography, and Canon implements this function correctly.

If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

No, it will go back to its original shutter speed. That's what I'd
expect to happen.

Good. You had me worried there for a minute.

But when fn 3 is not enabled, there is no change in
the shutter speed in Av mode, that's what is baffling me.

Av mode is a "creative mode". Creative modes are modes in which you don't
get backstabbed by automagic magic doing the wrong thing. If you want the
parts of the scene not illuminated adequately by the flash to be
underexposed, you have to tell the camera that.

David J. Littleboy
Tokyo, Japan

Dave Bowman wrote:
On Wed, 22 Sep 2004 14:47:59 +0900, "David J. Littleboy"
wrote:

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient
light
in insufficient.

Sure, but you'd expect that all else being equal (aperture), if the
flash is available, the required shutter speed should be faster, this
doesn't appear to be the case.

No the camera is assuming you want to use the flash ONLY to fill in some
shadows on the subject, NOT supply the primary light. You can choose other
settings on the camera to cause it to do as you believe it should. It
offers you the choice once you learn how to use it.

This is the way most cameras work. Check the manual out for "fill in
flash" for more information.

Check out:

http://www.danheller.com/tech-fillflash.html

For some information and examples of fill in flash.


A slightly more concrete example is my office in the evening. Bright
enough in there to read. Using F8, the shutter speed the camera wants
is 0.8 seconds, pop up the flash, maybe it drops to 0.4 but usually
stays at 0.8. But I know you can take a much faster photo under these
conditions, and certainly in the auto-modes, the camera is smart
enough not to use so slow a shutter speed.


If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

No, it will go back to its original shutter speed. That's what I'd
expect to happen. But when fn 3 is not enabled, there is no change in
the shutter speed in Av mode, that's what is baffling me.


D

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

Dave Bowman wrote:
On Wed, 22 Sep 2004 14:47:59 +0900, "David J. Littleboy"
wrote:

For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

That's how fill flash is supposed to work. It fills in where ambient
light
in insufficient.

Sure, but you'd expect that all else being equal (aperture), if the
flash is available, the required shutter speed should be faster, this
doesn't appear to be the case.

No the camera is assuming you want to use the flash ONLY to fill in some
shadows on the subject, NOT supply the primary light. You can choose other
settings on the camera to cause it to do as you believe it should. It
offers you the choice once you learn how to use it.

This is the way most cameras work. Check the manual out for "fill in
flash" for more information.

Check out:

http://www.danheller.com/tech-fillflash.html

For some information and examples of fill in flash.


A slightly more concrete example is my office in the evening. Bright
enough in there to read. Using F8, the shutter speed the camera wants
is 0.8 seconds, pop up the flash, maybe it drops to 0.4 but usually
stays at 0.8. But I know you can take a much faster photo under these
conditions, and certainly in the auto-modes, the camera is smart
enough not to use so slow a shutter speed.


If I use custom function 3 and force it to 1/250, then the shutter
speed is always displayed as 250, which isn't necessarily what I want,
or the right thing.

Hmm. In Av mode, fn 3 enabled, does it stay at 1/250 when you close the
flash?

No, it will go back to its original shutter speed. That's what I'd
expect to happen. But when fn 3 is not enabled, there is no change in
the shutter speed in Av mode, that's what is baffling me.


D

--
Joseph E. Meehan

26 + 6 = 1 It's Irish Math

In article ,
Dave Bowman wrote:
When using any of the "creative" modes such as Tv, Av, and M, the
camera doesn't seem to be aware when I have the built in flash popped
up. For example, if I use Av mode indoors in the evening, the
exposure meter will point to zero with a shutter speed of, for
example, 1 second. When I pop up the flash, the shutter speed does
NOT change.

It's meant to do that. Scene exposure and flash exposure are controlled
seperately.

If you want to use the flash as your primary source of exposure, use P or M.
If you're using M, ignore the meter at the bottom, just set a shutter speed
of 1/250 or slower, and whatever aperture you want. The camera will use the
flash to expose the scene for you.

If I set the flash exposure compensation at +2, there is some
difference, but I don't think that's really the correct approach
anyway.

That tells the camera to try and use the flash to make your subject white.

Can anyone help? The instruction manual implies that with Av mode,
for example, when you pop up the flash, the shutter speed should be
recalculated.

Absolutely not, and you wouldn't want it to. In Tv and Av, the autoexposure
is for ambient light. Any flash, as David Littleboy says, is for fill-in.