Question to Canon ST-E3-RT & 600EX-RT

So I was thinking on gettin g 2x 600 EX-RT, and a ST-E3-RT.

I just now discovered, that the ST-E3-RT unlike the ST-E2,
cannot fire an AF Assist beam.

Is it possible to let a remotly controlled flash use his built-in Beam?
(In case you are trying to make pictures in complete darkness).

OR is it possible to turn the 600EX-RT's flash completly off, and use it only for AF-Assist beam?

If none of the above is possible, can a ST-E2 fire off the 600EX-RTin "conventional" triggered by light mode?!

Thanks in advance!

Doesn't matter if there is no assist beam. You can press the DOF button on your DSLR and as along as the flash is connected via TTL it will strobe a modelling light for about 1.5 seconds, letting you focus within that time period.

Brea wrote in post #16500430
Doesn't matter if there is no assist beam. You can press the DOF button on your DSLR and as along as the flash is connected via TTL it will strobe a modelling light for about 1.5 seconds, letting you focus within that time period.

Thank you very much Brea, actually I did not even know about this funcion.

But there are some cases, when you should not "strobe".
(For example when photographing a Horse at night)

So I would still be interested in the above, if they are possible.

If you have a 600 EX-RT on camera and a second 600 EX-RT off camera, yes you can have the on Camera 600 Flash act as a Focus Assist and not fire Flash.
On Camera Flash as Master
Menu 2
First Option, Picture of Camera Flash 3 lines/ 0 Lines, Touch button underneath
As you tap button you will notice the Flash Icon just below the ETTL, Master Etc. not in menu bar options, will have 3lines or no lines as you tap.
Press your Flash Test button in each option and notice.

Hope this helps.

Nick5 wrote in post #16500732
If you have a 600 EX-RT on camera and a second 600 EX-RT off camera, yes you can have the on Camera 600 Flash act as a Focus Assist and not fire Flash.
On Camera Flash as Master
Menu 2
First Option, Picture of Camera Flash 3 lines/ 0 Lines, Touch button underneath
As you tap button you will notice the Flash Icon just below the ETTL, Master Etc. not in menu bar options, will have 3lines or no lines as you tap.
Press your Flash Test button in each option and notice.

Hope this helps.

Thanks Nick, that helps, altough I do not yet have a 600EX-RT, but If I understand it properly, then the AF Assist beam fires, but the flash will not.

That is exactly something I need, (I do not understand why the ST-E3 RT does not have an AF assist beam )

But thank you very much for the info!

You can also use the optical system supported by the ST-E2. Your 600 EX-RT will then essentially mimic a 580 EX II.

You can also hold out for the Yongnuo equivalent of the ST-E3-RT (announced) that WILL have a AF assist beam included. It is my understanding it will be compatible with Canon's system, so that you can mix 600EX-RT's with the Yongnuo trigger and 600-equivalent flashes all with RT capability.

mike1812 wrote in post #16502040
You can also hold out for the Yongnuo equivalent of the ST-E3-RT (announced) that WILL have a AF assist beam included. It is my understanding it will be compatible with Canon's system, so that you can mix 600EX-RT's with the Yongnuo trigger and 600-equivalent flashes all with RT capability.

According to THIS the Yongnou version is available within a few days. All the indications are that it has all the capabilities of the Canon ST-E3-RT plus AF assist and ability to support Gr mode in pre-2012 cameras. Both major omissions on Canon's part.

Good to know David. If these work as described, I'm betting we'll see a lot of ST-E3-RT (Canon) units on the "For Sale" forum pretty soon. I'm pretty sure I'm going to order one to test and will sell the Canon if it works as advertised (which is a good bet given Yongnuo's track record).

yes, i have 2 x 600ex rt and 2 x st-e3.
in ourdoor, the radio trigger st-e3 works perfectly and i do not really need any assist beam to help in AF.
in indoor lowlight, you can (as mentioned) put a 600ex onto the hotshoe of your camera and "Disable" firing of flash. then the beam can help.
please note that if you are using the 2013 model then the focusing points fr the flash and the camera should be the same. if you using camera bodies before 2013, the flash may have more points than the body -> not much of a concern but gd to know.
Scott