I have a 1D Mk4. Most often I am shooting as a secondary job duty for the agency I work for so it is not a full time gig. When I shoot it is an a photojournalist type setting. capturing photos as things happen. I prefer to shoot in shutter priority mode as I often am shooting fast moving subjects. I have adjusted some of my custom settings to increase my chances of capturing the shot. One of the more useful setting is the Safety Shift. I currently have it set to ISO. It has been working fine outdoors. However when I shoot indoors using a flash it stays enabled and sets my ISO to some craxy high ISO then fores the flash. Now I capture a good exposure but at 10000 ISO it tends to be a bit grainy...
Is there a setting I am missing that disables Safety shift when using a flash or do I just need to be shure I am in Manual mode when using a flash?
I hadn't thought to look but having just used my 1D4 recently to shoot a parade held in the dark I can confirm I got the same result. Having just looked this up it looks like we both need to disable Safety Shift when using a flash that we want predictable results from. The manual clearly says safety shift also works when a flash is used. Based on my results it really didn't think the flash would be very powerful (it is the 580EX) because a lot of photos are at ISO 12800. I used a 1Ds2 & 430EX set to ISO 800 & got good results from it & I think I had set the 1D4 to about the same or maybe ISO 1600.
(time to make a tiny cheat sheet to stick somewhere so I know what to reset when needed.)
You don't have to shoot in manual mode, just change the ISO setting. However for flash shooting I'd recommend using the manual mode where you have total control of Av, Tv and ISO. For your kind of shooting, just use the flash in ETTL, it'll worry about exposure.
I don't think the safety shift was what caused the high ISO. In Av and Tv modes, the camera assumes that you want the flash to be fill light only so it will measure ambient light and use the flash as fill and if your ambient light is low (indoors, night) the ISO will be high. It's best to use M to set Av, Tv, ISO then set flash to ETTL. You can shoot away without thinking more about it.