Getting 3 different Speedlite flash models to work together

[grinolot]

How can I get my flashes (2- 430EX III RT), (1-430 EX II) AND (1-580 EX II) to work together with or without my ST-E3-RT transmitter if possible?

I would like to set them up for head shots and use a main and fill light, hair light and background light.

[grinolot]

I forgot to add I'm using this setup with my 80D.

[kvbarkley]

Since they are all not RT models, you will need to use optical transmission. I would use the 580EX as the master and the others as the slaves. The manual for your camera has a pretty good discussion on how this all works. If you can, find a used copy of Syl Arena's Speedliter's handbook.

[deebatman316]

Well the 580EX II is the only speedlite the OP has that can be a sender in Optical Transmission. The 430EX III-RT can be Sender in radio mode only. Now your camera’s built in flash can be used as a sender. But limitations do exist doing this.

[grinolot]

Maybe I'll sell the 580 and 430 (non RT) and get a 430RT

[p4pictures]

Your EOS 80D can control up to two groups of off-camera units using optical triggering - it emits pulses of light from the built-in flash on the camera. 

You then need to set the Speedlites you have to wireless slave mode (termed receiver in more modern units). Also make sure that both camera and Speedlites are all using the same channel, there are four to choose from. Each Speedlite will need to be assigned to either group A or group B depending on how you setup the camera. Also it is important that each Speedlite can "see" the light from the camera or they will not fire.

If you choose to use the ST-E3-RT on the camera, it will only be able to control the 430EX III-RT Speedlites.

If you use the Speedlite 580EX II on the camera, it can control up to three groups of flashes using optical wireless. This would allow it to control each of the other Speedlites as optical wireless slave units even in separate groups. If the Speedlite 580EX II on the camera is also firing, then it will be part of group A. You can do high speed sync with the Speedlite 580EX II on the camera. 

[DougsGraphics]

Good information already provided on using what you have today -- a great place to start. I would just add a consideration if you think that you might do more studio or location portrait work in the future. Canon speedlites are great tools for work on the go (I have in my gear and routinely use 5 units) but lack the output and recycle capabilities (but I love that these units all have the capabilities to accept external power input) of a studio strobe unit. If someday you might want to do more of this type of work, there are great 3rd party options for controllers and receivers that are compatible with your current Canon gear and also provide compatibility to integrate other strobes. For example, the Flashpoint/Godox R2 controllers and matched receivers (and probably others, this is just a system I use and am familiar with). These are very flexible and expandable systems that integrate well with the Canon speedlites. Just a thought as I went through this conundrum in my past ...