Optoma HD25e screw

[orfeas76]

I just bought Optoma HD25e.
I am trying to put it on a big speaker tripod and screw it via a single point for quick releasing.
I cannot find anywhere in the manual the screw type of the big screw mount.
It looks like SLR standard 1/4''-20 but it is not, the screw doesn't get in.

 

[orfeas76]

to be more specific the diameter of the thread is the same as SLR-standard
but the thread itself is denser.

 

[paulr2006]

I'm guessing it might well be an M6 but you could always give Optoma a call to confirm