G1 P vs AV modes (Defect?)

I have owned my G1 for a while, and I am a relative newbie to photography. Usually I shoot in P mode and adjust Ev, etc., but that's as far as I have taken the manual capabilities of the camera. Tonight, I decided to do some experimenting with other modes (Tv, Av) and I noticed a very strange thing. While shooting with P mode (indoors), the shot will be shot at 1/60 and F2.5 with the 420EX flash. Now, when I go to AV mode and set the aperture to 2.5, the camera shoots the same shot at 0.4 seconds. No how big I set the aperture (with or without the external flash) shots in Av mode always have a far slower shutter speed than the same aperture in P mode. The converse does not happen in TV though. It seems to behave correctly.

Is this normal (doesn't seem like it)? Has anyone else noticed this with their G1? Thanks for your help.

Brad Swanson

Brad Swanson said:

I have owned my G1 for a while, and I am a relative newbie to
photography. Usually I shoot in P mode and adjust Ev, etc., but
that's as far as I have taken the manual capabilities of the
camera. Tonight, I decided to do some experimenting with other
modes (Tv, Av) and I noticed a very strange thing. While shooting
with P mode (indoors), the shot will be shot at 1/60 and F2.5 with
the 420EX flash. Now, when I go to AV mode and set the aperture to
2.5, the camera shoots the same shot at 0.4 seconds. No how big I
set the aperture (with or without the external flash) shots in Av
mode always have a far slower shutter speed than the same aperture
in P mode. The converse does not happen in TV though. It seems to
behave correctly.

Is this normal (doesn't seem like it)?

Click to expand...

I don't have the G1, but on the two Canon SLR's I have, this is the expected behavior. It allows for two different flash techniques, each of which have their place.

AV mode with a flash uses the flash in fill-flash mode, which will behave just as you described. Here, the camera sets the flash to fire long enough to properly illuminatte the main subject, but sets the exposure based on the lighting in the room. This yields a shutter speed that is much slower than if you were using the flash alone. Fill-flash is wonderful if you want it, particularly on bright sunny days, but for dark situations you'll need a tripod to keep the camera steady.

When you're in P mode, the camera is setting the shutter speed based on the flash exposure only, so the shutter speed is much higher. However, only what gets illuminated by the flash will be properly exposed in the picture. But, it does allow for hand held pictures in low light since the short flash duration freezes the action.

Some cameras have a slow-synchro mode which does the same thing as fill-flash.

Rick Cameron

Rick Cameron said:

Brad Swanson said:

I have owned my G1 for a while, and I am a relative newbie to
photography. Usually I shoot in P mode and adjust Ev, etc., but
that's as far as I have taken the manual capabilities of the
camera. Tonight, I decided to do some experimenting with other
modes (Tv, Av) and I noticed a very strange thing. While shooting
with P mode (indoors), the shot will be shot at 1/60 and F2.5 with
the 420EX flash. Now, when I go to AV mode and set the aperture to
2.5, the camera shoots the same shot at 0.4 seconds. No how big I
set the aperture (with or without the external flash) shots in Av
mode always have a far slower shutter speed than the same aperture
in P mode. The converse does not happen in TV though. It seems to
behave correctly.

Is this normal (doesn't seem like it)?

Click to expand...

I don't have the G1, but on the two Canon SLR's I have, this is the
expected behavior. It allows for two different flash techniques,
each of which have their place.

AV mode with a flash uses the flash in fill-flash mode, which will
behave just as you described. Here, the camera sets the flash to
fire long enough to properly illuminatte the main subject, but sets
the exposure based on the lighting in the room. This yields a
shutter speed that is much slower than if you were using the flash
alone. Fill-flash is wonderful if you want it, particularly on
bright sunny days, but for dark situations you'll need a tripod to
keep the camera steady.

When you're in P mode, the camera is setting the shutter speed
based on the flash exposure only, so the shutter speed is much
higher. However, only what gets illuminated by the flash will be
properly exposed in the picture. But, it does allow for hand held
pictures in low light since the short flash duration freezes the
action.

Some cameras have a slow-synchro mode which does the same thing as
fill-flash.

Rick Cameron

Click to expand...

Thanks very much for the info Rick. Sounds like this is probably what is happening. I'm so new to photography, I need to ask these silly questions from time to time. Thanks again.

Brad Swanson

Hi Rick,
Just confirming what Brad wrote.

I have a G1 and EOS5 and they both work the same in these modes. However, the EOS5 has a "Custom Function" that can turn off the slow speed synch.
What you are getting in Av is "Slow Speed Synch"
Regards,
**** S, Temecula, CA

Should be "Hi Brad-just confirming what Rick wrote"!!
**** S

**** S said:

Should be "Hi Brad-just confirming what Rick wrote"!!
**** S

Click to expand...

Thanks for the confirmation, ****. Glad to know that my camera is normal.

Brad Swanson

Brad Swanson said:

Thanks very much for the info Rick. Sounds like this is probably
what is happening. I'm so new to photography, I need to ask these
silly questions from time to time. Thanks again.

Click to expand...

It's not a silly question. If you're new to photography, you're about to go down a wonderful path! It's just kind of confusing sometimes

Deciding when to use natural light, fill-flash, or just flash is sometimes obvious, sometimes just personal preference. As an example, here's a thumbnail of an image I took with my D30 this summer of a lizard in Kentucky.



You can view a larger picture at

http://racphoto.com/Parks/KY/NaturalBridge/CRW_8669-ed.jpg

I used fill-flash in this case. I wanted to capture the lizard just peeking around the tree with the green of the forest completely blurred behind it. If I had used flash only, the camera would have only used the flash for exposure, which wouldn't have illuminated the forest in the back and left the background really dark.

If I hadn't used any flash, the lizard wouldn't have been illuminated very well because it wasn't getting good light. I did take other pictures that day that didn't use flash, just depended on the lighting. If the natural light is good, I much prefer it to fill-flash, but in this case I didn't like the light. The fill-flash also illuminated the blue patch on the lizard's throat, which wouldn't have been very visible otherwise.

Rick Cameron