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[on:]

http://adrian.onsen.ca/2011/05/af-assist-tool-version-1-0/

I know this is a little bit off topic from Arduino, but I will be using my Uno.  I'm planning to use a 1w IR 808nm laser diode to assist with AF on my Canon DSLR.  These are available on Ebay for less than $15.  It would give Auto Focus an infinite range in complete darkness.  Anything past the range of the laser would be almost infinity as far as focusing is concerned.  I have a few questions for you photography buffs before I begin.

Will 808nm work for focusing? 
I've googled and near-IR is typically used.

Will pin 1 of the hotshoe turn on the laser at the correct time?

Will this wavelength have a huge effect on exposure in the dark?
If so we have a night vision video camera!

My Uno will only have a simple task.  To delay the timing from pin 1 so it won't interfere with the picture.  Also to keep the diode from overheating without a big heat sink.  I need to keep track of how long it was on in the last minute.  Or use a thermistor?

[Reply #1 on:]

No blink reflex in this part of the spectrum, so eye safety issues with that type of power.

[Reply #2 on:]

Thanks for the warning!

For focusing it should work when the beam is large and spread out, especially when there are humans in the picture.  When I am trying to focus on a subject ~100m away then I will want to focus the beam some.  Still it will be many inches in diameter.  It is much faster when it is tightly focused but this is not needed.  It will be wide when being used as night vision.  How can I control this?  A servo moving the lens?  Any ideas?