ST-E2 Speedlite transmitter helping focusing?

[JR]

Has anyone tried or used the Canon ST-E2 transmitter (used for wireless flash) to simply help focusing without a flash?

I noticed that focusing on my 5d mk II is always better (even if I shoot the light away from subject) when I use my 580 speedlite.  I read somewhere that because the flash sends a signal first to help focusing, it helps.  I also saw people claiming the transmitter alone which basically fires that beam as well but without the flash can help focusing.

I just find in medium to low light situation my 5D mkII focusing is very eratic...(maybe it is the user!).  I always use the single center focusing point.

Thanks for any input.

JR

[Mark D5 TEAM II]

Like the Speedlites, the ST-E2 has a red AF assist beam to help the camera AF in low-light. You can use it for that purpose alone.

[JR]

So it does indeed help focusing when used alone then.  That's what I was hoping.  If so I will get one for that alone!  Small price to pay to have more shots in focus!  Thanks.

[neuroanatomist]

So it does indeed help focusing when used alone then.  That's what I was hoping.  If so I will get one for that alone!  Small price to pay to have more shots in focus!  Thanks.

The ST-E2 just to have something less bulky on your hotshoe?  Because you can configure your 5DII + 580 speedlite so the AF assist lamp on the speedlite fires, but the flash itself does not fire...

[JR]

Thanks for the tip Neuro.  I will try that.  But yes having something lighter will be a plus for me, so the transmitter will be of good use!

[outsider]

JR, I've been using a ST-E2 (at least the Younguo version of it) to help my 40D focus in dim light for a while now, and have had great success with it.

The 580 speedlight will have a longer reach with the AF assist, as the assist light is more powerful.

But no doubt, the ST-E2 helps a great deal.