Using Auto Focus on the Canon 6D in the dark, with very little contrast except flash light

[birdie321]

I am trying to get my Canon 6D to lock on to a moving subject in the dark.  I am using the 430ex II flash.  The subjects will be moving towards us within twenty feet.  I am using a Canon 50mm 1.4 lens.  Unfortunately my flash infrared meter was not working when I tested this.  My question is, what settings will I need to use, and does the infrared on the flash control metering as well as autofocus?  

Thank you for all suggestions. 

[kvbarkley]

So you want to use infrared assist? You are right at the edge. The center point has a range of 32 feet and the "periphery" has a range of 16 feet, with a lens longer than 28mm.

The infrared does not do metering, nor would you want it to. Use manual.

[diverhank]

The AF-Assist function of the flash is usually the default so it should work unless at some point things get changed (pretty easy to do).

You should check:

1. Go to custom functions on the flash and make sure AF-Assist is enabled.  Flash settings trump camera settings.

2. Got to custom functions on the camera (C.Fn II - 5) and make sure that AF-Assist is enabled.

If you've done this and the AF-Assist still doesn't come on, it might be because it's not dark enough or the camera can AF without needing the AF-Assist.

AF-Assist is just that...it does not do metering.

[birdie321]

Thanks diverhank.  

On the custom functions II setting number 6 is titled:  Lens drive when AF impossible

0 - Continuous focus search

1 - Stop focus search

If my subject isn't moving around too much, I am assuming I would set this option to 1.  Or does the 0 opiton work well enough to use?   I have read where the AF assist beam only works when you are using One shot mode which make sense rather than trusting server or AF focus.    

[diverhank]

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@birdie321 wrote:

Thanks diverhank.  

On the custom functions II setting number 6 is titled:  Lens drive when AF impossible

0 - Continuous focus search

1 - Stop focus search

If my subject isn't moving around too much, I am assuming I would set this option to 1.  Or does the 0 opiton work well enough to use?   I have read where the AF assist beam only works when you are using One shot mode which make sense rather than trusting server or AF focus.    

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Actually, imho, you want to set this to 0 not 1.  If you set it to 1, the camera decides when it is that AF is impossible, which in my actual experience, quite often...resulting in your AF not working when it should.  You only set this to 1 if you have really big and older generation supertele (like a 600mm f/4) that would be hunting around too much wearing down your battery.  Modern supertele doesn't even do this (hunting) so setting it to 0 is recommended.

[birdie321]

diverhank,

I am a firm believe in test, test, test.  So next week I will go with a friend to a "dark" field or something.  I just wanted to understand what I need to set before I go.  Thanks for your help and suggestion.  I would have thought to change the default  to 1, but you may be right. 

thanks!

[kvbarkley]

I think it is time to tell us what you specifically want to do. On the Arduino forum we call this an "XY Problem", where we keep getting little pieces of the problem, when sharing with us the whole problem will let us supply answers in directions you never thought of.

[birdie321]

kvbarkely, 

I am shooting zombies.  That's right, a cosplay with zombies and survivors.  But the zombies will be slowed down by a legal waiver (no running in the dark) and they can only use pool noodles to "bite".  The survivors will use nerf guns to make kills.

So this is the "XY" Problem.  

Does this help?  The problem domain will be as described already: 

- dark

- flash lights

- 20, 30 ft from action shots

- settings on 430ex II flash for AF assist 

- settings on the 6D  

 THanks!

[Waddizzle]

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@birdie321 wrote:

Thanks diverhank.  

On the custom functions II setting number 6 is titled:  Lens drive when AF impossible

0 - Continuous focus search

1 - Stop focus search

If my subject isn't moving around too much, I am assuming I would set this option to 1.  Or does the 0 opiton work well enough to use?   I have read where the AF assist beam only works when you are using One shot mode which make sense rather than trusting server or AF focus.    

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I like to leave this function set to 1.  It is true that quality modern lenses they rarely get lost focusing.  So, for the majority of your shooting scenarios, the setting never really comes into play.  

It is when you push the limits of your gear that the setting becomes more significant.  I have found that if the lens gets lost, then the lens rarely recovers in time to capture the shot.  I figure, why not let it shutdown AF when it gets lost.

Setting it to 1, really seems to save battery power, too.