Trouble slaving Yongnuo YN600EX-RT with Canon MT-24EX

Ok, first off I have zero experience working with wireless flash. I've mainly worked either with maco using the Canon MT-24EX exclusively or landscapes using natural light. But a recent project required I shoot indoors lager than 1:1 and the MT-24EX alone just doesn't cut it.

I ordered a couple Yongnuo YN600EX-RT I was hoping to slave to the MT-24EX but have had no luck getting them to work other than through optical trigger. I set everything up exactly as suggested in the manuals. MT-24EX needs to be set to ETTL with ratio at A:B C (with C being the slave). Slaves get set to ETTL slave mode in group C. Both units set to the same channel. This produces no results. The Yongnuo doesn't see the Canon.

I'm wondering if it's an issue between the body, 5DSR, and the MT-24EX because the manual lists other models with which wireless ETTL is not compatible but obviously the 5DSR is too new to be included in that list. Does anyone know if this is the case?

Slave does trigger using optical ETTL, which on the Yongnuo is ETTL SC, but I'm such a noob I don't understand what disadvantages come with using this method. Is the Yongnuo really exchanging information with the Canon or just firing off when it detects the flash of the MT-24EX?

I completed the project using three Yongnuo YN600EX-RT with one on camera acting as master and wireless worked flawlessly. So I'm past that hurtle but would still like to get the best use out of my gear.

Thanks in advance for any info or suggestions!

The MT-24EX is not of the new "RT" (radio transmitter) era, and thus I believe can only trigger slaves looking for the optical pulses of the older EX and EXII models.

EDIT:
I'm no expert on either of the flashes you have, but the specs say that the Yongnuo is compatible with "Canon and Nikon Optic Wireless Slave Modes"

Not at all sure what the settings are though to make it work that way.

Precarious333 wrote in post #17801125
...

Slave does trigger using optical ETTL, which on the Yongnuo is ETTL SC, but I'm such a noob I don't understand what disadvantages come with using this method. ...

Wait, I'm confused here. The above is exactly how the yongnuo would slave from an optical master flash, if you have this working, then what is NOT working?

CyberDyneSystems wrote in post #17801149
Wait, I'm confused here. The above is exactly how the yongnuo would slave from an optical master flash, if you have this working, then what is NOT working?

CyberDyneSystems wrote in post #17801149
Wait, I'm confused here. The above is exactly how the yongnuo would slave from an optical master flash, if you have this working, then what is NOT working?

Is there any disadvantage to working optical as opposed to wireless? That's mainly my question in regard to what you quoted. I don't get if ETTL info is being exchanged when wireless won't work. Doesn't make sense to me but I don't have a full grasp of what is going on.

Thanks for the replies, by the way. The Yongnuo units already have transceivers built in and supposedly so does the MT-24EX but it may be the wrong format as you suggest. Yongnuo should be fully compatible with Canon but it may just be the MT-24EX is too old.

ETTL should work with the old optical system. Keep in mind this was how Canon did it (and all other flashes for that matter) up until the new RT system. So this should not be an issue.

There is no "Transceiver" in the MT-24EX flash. It uses optical pulses to trigger Canon slaves in ETTL. It is not compatible with the Radio trigger system of the new 600 RT

As for the disadvantages of Optical;

Less consistent in some shooting environments where the optical pulses may not be read perfectly. (out doors over longer distances, etc. I've never run into this, but I've read about it.)

You lose the ability to remotely alter settings in the slaves that wireless could offer.

IMHO, unless you run into a barrier, I would not worry about it. However, I am not an RT shooter, so I don't know what I'm missing.

You may consider buying some Yongnuo RT gear to make it work better,. but not sure how you'd do it with the twin light attached to the camera.

CyberDyneSystems wrote in post #17801168
ETTL should work with the old optical system. Keep in mind this was how Canon did it (and all other flashes for that matter) up until the new RT system. So this should not be an issue.

There is no "Transceiver" in the MT-24EX flash. It uses optical pulses to trigger Canon slaves in ETTL. It is not compatible with the Radio trigger system of the new 600 RT

As for the disadvantages of Optical;

Less consistent in some shooting environments where the optical pulses may not be read perfectly. (out doors over longer distances, etc. I've never run into this, but I've read about it.)

You lose the ability to remotely alter settings in the slaves that wireless could offer.

IMHO, unless you run into a barrier, I would not worry about it. However, I am not an RT shooter, so I don't know what I'm missing.

You may consider buying some Yongnuo RT gear to make it work better,. but not sure how you'd do it with the twin light attached to the camera.

Ok, great! Thanks for clearing some things up for me. In the situations I'm working with optical should work fine then. I don't need multiple groups of slaves or anything as complex as that. Just reinforcement of the output of the MT-24EX or fill lighting. Thanks for the help.