AS assist v3 project update: The light source

In the search for a focus solution, I am going to abandon the laser pointer light source in favor of an AF assist light from a proper flash unit.

Doing some research here and looked at a whole bunch of flashes, and some of the flash manuals have a range in which the AF illuminator/assist light is effective. The listed number is the max range listed in the official user manual (in meters and feet).

-380EX, 10m/33ft
-420EZ, 8m/26ft
-420EX, 7m/23ft
-430EZ, 10m/33ft
-540EZ, 15m/50ft
-580EX II, 10m/33ft
-580EX, 10m/33ft

-4000AF, 7m/23ft
-2800AF, 5m/16ft
-3200i, 9m/29ft
-3500xi, 9m/29ft

-SB24, 25, 26 had no range listed for the AF assist light.
-SB-900, 10m/33ft
-SB-800, 10m/33ft

-622 and 622 mark II, 6m
-866 and 866 mark II, 10m

Ten meters seems to be the benchmark. So far, the Canon 540EZ seems to be the winner, with a range of 15m. That’s more range then Canon’s current state of the art flash, the 580EX II.

I have a broken 380EX flash which has a range (for it’s AF assist light) as good as a 580ex, so it will be a good start.


Just bought a new 540EZ AF assist module from ebay for under $30 after shipping. Have to figure out the voltages I can apply to this unit, without burning it out.

1 thought on “AS assist v3 project update: The light source

  1. Pingback: AF Assist tool v3.0 – more testing | adrian's domain

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