How do I cancel a shot?

Is there any way, short of turning the camera off, to interrupt a long exposure before its time is up on the 400D?

No, there is way to cancel a shot.

TMR Design wrote in post #3232456
No, there is way to cancel a shot.

HUH?????

Just turn the camera off. It's fine and won't damage the camera.

Yes of course. I just meant that there is no function or cancel button. Once you fire a shot the only way to 'cancel' it is to turn the camera off.

OR pull the Cf door open and then shut it... easier than finding the impossible switch on the XXDseries cameras.

There is no need for a separate cancel button if the on/off switch will do the same thing. The early DSLRs took a while to boot, but the new ones come on almost instantly so the time to reboot does not matter.

Take lens off, prise down the mirror with a large screwdriver this will block all light from reaching sensor.

b1gdaddy wrote in post #3232954
Take lens off, prise down the mirror with a large screwdriver this will block all light from reaching sensor.

Toss camera into swimming pool, that should stop most of the electronics and prevent a full image.

Odd question anyway, How long a shutter speed is needed where you think you have tome to do ANYTHING to stop it? Just wait the two seconds and then delete it. CF cards are huge there is a delete button on many cameras, what is the dire need anyway?

Perhaps he's got it on a four week exposure

Anke wrote in post #3234983
Perhaps he's got it on a four week exposure

battery would die by then :O

I've done this before on my 30D and it wouldn't stop writing on the card for a 30 minute exposure.

I've turned the camera off heaps. No ill effects.

Especially when you've got it set for 30 seconds, plus noise reduction.