# ST-E3-RT master + autofocus assist from a slave 600EX-RT?



## time123 (Sep 11, 2015)

If you have a camera mounted ST-E3-RT running as master plus any number of radio connected 600EX-RTs is it possible to utilize the AF assist on one of the 600s since the ST-E3-RT doesn't have the capability or is AF assist only possible from the master unit? I like the size of the ST-E3-RT but I also like the AF assist on the 600s and since the ST doesn't have the AF assist built in I have been wondering if there is a way around it. I've been reading around the Internet as well as checking out the product manuals but unable to find an answer to the question (or maybe I missed it?). Thanks in advance!


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## privatebydesign (Sep 11, 2015)

No, AF assist only works from a camera mounted Master 600-EX-RT, in Slave Mode the AF assist doesn't trigger.


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## andrewflo (Sep 14, 2015)

If you haven't seen it already, you may want to take a look at the Yongnuo YN-E3-RT: http://www.amazon.com/Speedlite-Wireless-Transmitter-YN-E3-RT-ST-E3-RT/dp/B00H7XFOKO

It is a clone of the Canon, but includes a AF assist light. There are generally pretty positive reviews but a few here and there pointing out a few disadvantages, namely slightly lower build quality. But for $90, it's a killer value.

Also, the AF light is not perfectly centered with the FOV. It's strange, but look at some of the reviews demonstrating it.


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## privatebydesign (Sep 14, 2015)

I had and used the YN-E3-RT, it wasn't bad, thought the misfire rate was way higher than with the ST-E3-RT I also own, but the AF assist light is a joke. Do not get a YN-E3-RT thinking you are going to solve the assist problem.


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## benique (Sep 14, 2015)

I'm using the YN-E3-RT with 5 YN-600EX-RT Flashes. They have been very realiable. I haven't had any misfires. I had some minor issues with battery warnings on the flashes before I upgraded the firmware.

They have been a joy to use. The RT system is very reliable and much better than the optical system that I used with original Canon flashes. They're really more than worth the money.

I haven't really used the assist light. So I can't comment on that.


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## mrzero (Sep 14, 2015)

I believe the new Canon 430EX III RT will have an AF assist beam, along with its radio master capability. That might work out well here and also give you the option of fill flash as well.


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## IsaacImage (Sep 15, 2015)

Had 1st gen of Yongnuo version of ST-e3-rt - lots of troubles 
full story here
http://www.isaacimage.com/canon-st-e3-rt-knockoff/

Since than bought Canon original st-e4-rt, and last month got new gen. of Yongnuo as well as a back up.
All I can say , sometimes it's more reliable than Canon and in the dark situation once Canon is completely unusable Yonguo doing the job as a Champ.

One thing still bothering me the AF assets is still a bit off, but still works great.


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## pwp (Sep 15, 2015)

I'm using the YN-E3-RT which I've had for six weeks and used solidly. It's used to fire a bunch of 600EX-RT's. 
No misfires, useful AF assist. What a great buy.

I bought the original Canon ST-E2 a dozen or so years ago just for the AF assist. It was pretty useless as a trigger. What a bewildering oversight by Canon to leave AF assist off the ST-E3-RT. And what a gift to Yongnuo. 

-pw


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## arthurbikemad (Oct 12, 2015)

I have a YN RT remote, only as Mr Canon failed to included FA on the STE3RT. It blows my mind to why a flash soulution that will often be used in low light on a camera that cannot focus in the dark did not have it and was in the last ver? WTF would they do that.....who knows.... Like you say gives YN a slice of the market, well done Cannon, how kind of you, and gives me a backup not that I need one, I did look at the 430exrt.iii but seems if I am to carry another flash (already have 4 600s) then I'd rather have another 600.

Anyhow I have had a few YN flash guns over the years and as much as I like the price and they are good value for money, none of mine have lasted 

Oh I should add you also get second curtain with the YN RT remote, another feature that's not on the ST-E3-RT!


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## YuengLinger (Oct 12, 2015)

Great thread.


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## midluk (Oct 12, 2015)

I would not want to risk ruining my or anyone's eyes through the use of the laser based AF assist of the YN-E3-RT.


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## arthurbikemad (Oct 12, 2015)

midluk said:


> I would not want to risk ruining my or anyone's eyes through the use of the laser based AF assist of the YN-E3-RT.




Your not wrong, it's HARSH, I tried it on myself as a self portrait and MAN it's bright in low light! Mine is also on the piss and I thought wow, it's that on the level? NO it's way off, so much so I was surprised it locks on at all, however it does work, also the screens on the YN is poor, very fuzzy and faint, but for the money you can't complain, I got mine mainly for second curtain, God knows why Canon did not include it, AF assist ok ok but SC??? Weird....super weird that these features are included in the flash but not the trigger, these big wigs do make some strange decisions.

Maybe next time I will get the Shanny SN-ST-RT.


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## YuengLinger (Oct 12, 2015)

midluk said:


> I would not want to risk ruining my or anyone's eyes through the use of the laser based AF assist of the YN-E3-RT.



Really a laser? I have the 600ex-rt; it has a good, solid AF grid, maybe not as bright as the 580ex, but I'm sure it isn't a laser. 

Maybe just seems bright relative to very low light?


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## arthurbikemad (Oct 12, 2015)

Think mid means the YN-ST-RT, if its LED then its as bright as a laser! Its about 4x brighter than a 600EX-RT.


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## midluk (Oct 12, 2015)

YuengLinger said:


> midluk said:
> 
> 
> > I would not want to risk ruining my or anyone's eyes through the use of the laser based AF assist of the YN-E3-RT.
> ...


I'm sure the Yongnuo transmitter uses a laser for the AF assist. It is very bright and the dots have this laser-only speckle pattern.


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## Basil (Oct 25, 2015)

andrewflo said:


> If you haven't seen it already, you may want to take a look at the Yongnuo YN-E3-RT: http://www.amazon.com/Speedlite-Wireless-Transmitter-YN-E3-RT-ST-E3-RT/dp/B00H7XFOKO
> 
> It is a clone of the Canon, but includes a AF assist light. There are generally pretty positive reviews but a few here and there pointing out a few disadvantages, namely slightly lower build quality. But for $90, it's a killer value.
> 
> Also, the AF light is not perfectly centered with the FOV. It's strange, but look at some of the reviews demonstrating it.



I just bought a new 600EX-RT and needed a transmitter. Decided to go with the Yongnuo for exactly that reason - the AF assist beam. (Well, that and the fact it is a fraction of the cost)


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## jeffa4444 (Jan 8, 2016)

Another option is the Phottix Laso Transmitter it also has AF assist.


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