5D question...CFn 16?

.....Has anyone been using this safety shift function in Av mode?

...In high school football, I sometimes get exposure errors because of the white jersey vs dark pants composition of some of the player's uniforms. At shorter focal distances, it's not a frequent problem but at 200 mm it seems to happen more often.

...I'm thinking of enabling this function but if there are any problems or trade offs with using it, I'd love to hear about it from those of you who are familiar with using it.

....I have CFn 17 enabled which allows expanded 7 AF point tracking with AI servo mode. I'd like to continue using no. 17 as it appears to help get better consistency in focusing for me. I'm still not absolutely sure about that though.

Safety shift is used for flash.

Assume your camera has a sync speed of 1/250. If you set your lens at f/4.0 and the lighting is such that you need a shutter of 1/1000, with Safety shift off and a flash without High Speed Flash (or turned off) you will have a blown shot. With safety shift on, the camera will set the "safety" shutter speed at 1/250 and adjust the aperture smaller to get the correct exposure.

Of course with high speed flash, you will be able to shoot at f/4.0 and 1/1000.

I always use HS flash, but found I needed safety shift when I had the batteries out of the 580EX for a while to charge them (rather than a quick swap)...the 580EX forgets the HS flash setting....had to recover 5-6 shoots I took before I caught it.

John

Tim Rogers said:

.....Has anyone been using this safety shift function in Av mode?

Click to expand...

Back when I still used AE, yes, I always enabled safety shift. I don't really understand why anyone would NOT want it enabled except perhaps in special circumstances. And it's not just for flash.

- DL

Indeed it's not just for flash. I had it on but I turned it off the other day. I was shooting at f1.4 iso 1600, and safety shift dropped the shutterspeed to 1/30, which would cause motion blur, so I turned it off. Rather have an underexposed file than a shaky file!

Jan Luursema said:

I was shooting at f1.4 iso 1600, and safety shift dropped the shutterspeed to 1/30, which would cause motion blur, so I turned it off. Rather have an underexposed file than a shaky file!

Click to expand...

Good example of special circumstances. No matter what you do (on/off), this is a reminder that you've got to pay attention to what AE is doing to avoid pitfalls (one of the reasons I abandoned AE).

What would be more useful is a safety shift that affected ISO rather than Tv or Av.

- DL

Thanks everyone

....I'm going to try SS in Tv mode and see if I can progress past just using Av as my default shooting mode unless DOF concerns dictate it.