Can a Godox XPro transmitter for one brand fire a legacy flash for a different brand + X1R in TTL?

Question

I have recently moved from Canon to a Sony A7R IV and want to fire my Canon flash (600EX-RT) mounted on a X1R-C while using a XPro-S on camera.

I can successfully use this combination in manual mode, but in TTL mode, while firing the flash it does not generate sufficient light to illuminate the scene. No matter what compensation factor is used the light output remains constant. The same flash unit and X1R-C used on a Canon camera with a XPro-C works correctly.

My question is, is a XPro-S compatible with a X1R-C? Obviously if they are compatible any assistance on settings to make then work together will be most gratefully received.

Answer 1

No. While the X1R-C and XPro-S are compatible in terms of firing and possibly M power control, the Godox X1R receivers do not perform cross-brand TTL in the way the built-in radio transceivers in the Godox TTL full-sized speedlights (TT685, V860II, V1) do.

If, say, you were to purchase a Godox TT685-C and checked its firmware version was v3.1 or later, you could use it off-camera as a radio slave in TTL with the XPro-S. I use one that way with an XPro‑C on my 5DMkII, my XPro-F on my Fuji X100T, and my Xpro-O on my Panasonic GX7.

Obviously, however, trading in your 600EX-RT for a TT685-S, V860II-S, or V1-S, if you've moved completely to Sony would make more sense, so you could have a speedlight that did TTL/HSS on-camera as well as off-camera. Keep in mind, there is a known bug with Godox and Sony that TTL underexposes if used with wider-than-f/4 aperture settings. So, sticking with M and using, say, super-cheap $65 TT600 or TT600S single-pin manual speedlights may be another option to consider.

Alternatively, don't use Godox as your triggering system. Cactus's V6II transceivers can do cross-brand TTL in their X-TTL system.