XT and 430 problem

Here is some background. the onboard flash works fine in all modes (av, tv and m)

When I install my 430 on it works well in AV and M, but not it TV.
The moment that I turn the flash on, it changes the fstop to the highest setting available and will not change with shutter speed.

In AV mode i get 1/30 @f5.6.
In TV mode the fstop will not change with the shutter speed. IE 30s exposure at f32 or 1/200 at f32.

But if I turn the flash off, then every thing is normal again.

Whats going on here?

The flash shouldn't be affecting the exposure the camera chooses, try it without the flash and report back. Take a couple of shots and report the exposure (aperture/shutter).

Exactly, thats why i'm stumped.

I was just looking over the files and recalling what settings were changed, and there is another twist that might help.

av mode f5.6 at 1/200, 430 on M1/2power flash worked fine
tv mode 1/200 at f5.6, 430 on Ettl flash worked fine
tv mode 1/200 at f32 flashing with 430 on M 1/2 power.

Why would switching to Manual control of the flash cause the f stop to be closed down so much?

I don't think you can use the flash in Tv mode if the flash is set to manual mode. That's because, in manual flash mode, you need to be able to control the aperture to control the intensity of the flash lighting the subject. In Tv mode, you are controlling the shutter speed and hence relying on the camera to control the aperture. The camera doesn't like that so it set it to the smallest aperture available on the flash.

It makes sense, but I fail to see how its any different than AV mode where the speed is set by the ambient light. it should set for the background and let the flash do its thing in the front.

Oh well manual it is for me then.

Thanks guys,

In Av mode, you are controlling the shutter speed, which is what you need to do to control the flash output. The shutter speed is irrelevant to flash as long as it's at or below the max sync speed or the flash is set to high speed sync mode.

However, I do agree with you that Canon shouldn't disallow the use of Tv in manual flash mode. They should let the camera set the aperture based on ambient lighting and you can manually adjust the flash for whatever aperture was selected by the camera.

I've been used to shooting with a Konica slr for many years with it doing such a thing. seems odd that my 20 year old film camera allows it but an advanced camera like my canon won't...
I imagine that its an option on higher end cameras though...

Ross McT. wrote:
I've been used to shooting with a Konica slr for many years with it doing such a thing. seems odd that my 20 year old film camera allows it but an advanced camera like my canon won't...
I imagine that its an option on higher end cameras though...

Sad to say but my 1DmkII does the same thing, too. It would be nice if Canon could at least explain why they "crippled" the operation of the camera in Tv mode when the flash is set to manual mode. The "logic" I used to explain it in the previous post may sound good but, in all honesty, it really doesn't "cut it".

I find manual mode is usually best when i'm using flash, it allows me to ballance flash and ambient easily, and the results are reasonably predictable.