What thread size is the mounting bracket socket on the 600EX-RT?

[Camlane]

What thread size is the mounting bracket socket on the 600EX-RT?  The manual shows the SB-E2 bracket but apparently it is not available.

[jrhoffman75]

You can sometimes get bracket via eBay. It comes with off-camera cable. It's pricey.

[TCampbell]

It's not 1/4"-20 (20 means 20 threads per inch (TPI)).  It's finer than that.... it looks like it may be 1/4" 28 (which is another fairly common TPI used with 1/4" bolt diameters.)  1/4"-20 is the standard "coarse" thread and 1/4"-28 is the standard "fine" thread when dealing with 1/4" diamter threaded bolts.

I can't verify that though as I don't have a 1/4"-28 bolt to test for fit (but I am looking at my 600EX-RT now and can clearly see that it has finer threads.)  

There is, however, a 1/4"-20 mounting hole on the mounting foot that comes with the flash.  That's the plastic foot that has a "cold shoe" to attach the mount and allows it to stand on a table or floor.  On the underside of that plastic foot, there is a 1/4"-20 mounting hole.

If you'd like to use the mounting hole on the lower left side of the flash body itself, then you may need to get a 1/4"-28 bolt and test it for fit.

[MikeSowsun]

The thread is metric M6 x 0.5 

The SB-E2 is available on Ebay. The price may seem high but it includes an OC-E3 cord. 

[Camlane]

Thanks for your reply.  I knew it was not 1/4-20.  Your help is appreciated.