I do a lot of available light photography with f/1.2 and f/1.4 lenses. I use the "safety shift" mode (C.Fn I-6), which works great in combination with shutter priority mode (Tv). For example, I can leave the shutter setting to 1/1000th sec and rely on my camera to use a slower shutter when the scene requires to.

However, in certain situations the light is simply not enough and the external flash becomes inevitable. To be quick I like to keep the 430EX flash mounted on the camera and just switch it ON when necessary. Being able to quickly and simply switch from one method to the other is important to me.

The problem is, that the safety shift mode together with Tv mode leads to very long exposure times (even 1/5th second and worse), despite the flash is being fired.

  • switching off safety shift mode solves the problem - the camera uses 1/200th sec shutter and the final exposure is correct. That is fine, but I want to keep safety shift enabled for non-flash scenes.
  • switching to Av mode also gives me a 1/200 shutter, but I am not quite happy with the additional step when switching from av.light to flash scenes.

Is there a simpler way to force the camera on a 1/200 shutter when using flash in Tv mode, despite the safety shift function enabled?

  • 1
    \$\begingroup\$ Welcome to Photo Stack Exchange! I see you are asking well thought out questions and providing new answers to existing questions already! Thanks for the contributions! \$\endgroup\$
    – dpollitt
    Nov 15, 2011 at 22:53

1 Answer 1


I'm not sure there is a way to do exactly what you need, but this sounds like a situation where the 5D's custom functions may come in handy. If you don't already use them, you could, say, set C1 to be Tv at 1/1000 with safety shift on, and C2 set to Tv at 1/200 with safety shift switched off, meaning you can easily switch between the two without having to burrow through the Custom Functions menus. It may not be as straightforward as you need, but should make things a little easier for you.

  • \$\begingroup\$ good idea, but it's pratically the same as when I switch between Av and Tv mode (in Av mode, it stays at 1/200 fixed). Anyway, I'm wondering: can I even have different C.Fn settings for the C1-C3 modes? \$\endgroup\$
    – Udo G
    Nov 16, 2011 at 23:47
  • \$\begingroup\$ Yes, you can; custom functions are saved. \$\endgroup\$
    – user456
    Nov 17, 2011 at 6:56

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