Speedlite Transmitter ST-E3-RT | Pressure Test

[Mark Elberson]

I had the day off today and some spare time so I went outside to see how much range I could get out of my ST-E3-RT. This was by no means scientific, and since I had line of sight it was probably at least close to a best case scenario. Either way, I was more than thrilled with the results.

The claim: "two-way wireless transmission up to 98.4 feet" Canon

The results: 415 feet!

The method: I placed a Speedlite 600EX-RT on a light stand in the street in front of my house. With my 5DIII and ST-E3-RT I started walking backwards while clicking :-) I would stop at about 25 foot increments and took a few shots. I did this until the flash no longer fired. I did have successful triggers past the 415 foot mark but they were sporadic. At 415 feet I was able to take a succession of successful flash triggers in both Manual and ETTL.

I wouldn't expect these results in the field unless you were literally shooting in a field of course :-) I do think it was a worth while exercise though and shows that Canon was very conservative with their specs.

Here's what it looks like:

1/200 @ f/14 @ 105mm