What is the usual tripod screw size ? On say the base of a 5D3?

I know we have 1/4 " but what is it technically
I tried a 1/4 " UNC nut and that seems a little loose.

I want to know what is the exact thread and pitch size? So I can make a flash strap for connecting Speedlites to a lighting stand.

Any help appreciated

From Wikipedia: "Most consumer cameras are fitted with 1/4-20 UNC threads. Larger, professional cameras and lenses may be fitted with 3/8-16 UNC threads, plus a removable 1/4-20 UNC adapter, allowing them to be mounted on a tripod using either standard."

ISO 1220:2012 specifies it as either a 1/4"-20 UNC (Unified Coarse, what we have on all our Canon cameras) or a 3/8"-16 UNC (used only by large studio cameras). In older litterature you'll find references to "British" vs. "German" thread.

The original standard actually was 1/4"-20 BSW (British Standard Withworth) or 3/8"-16 BSW, but they are similar enough in their thread profile to fit both ways.

Thanks thats the info I needed.
Interesting the original standard was whitworth.
Maybe this cheap clamp was made using whitworth

I assume all new 2012 cameras are UNC from what was said?

Its 1/4 whitworth but 1/4 UNC will work... The pitch on the thread is close enough for them both to work

If it is a Whitford thread as "JEPhotography" states one key difference would be the included thread angle. Whitworth is 55 degrees vs. 60 degrees for UNC. The Whitforth would consequently need to be cut with some slop to allow the UNC at 60 degrees to be used without binding.

I personally was under the impression the current standard is 1/4-20 UNC. This is also supported by the fact that ISO 1222:2010, the current standard, as of 2010, states that the tripod screw is a 1/4-20 UNC or 3/8-16 UNC thread.

I don't know when they changed, but it's normal that something is a fact for several years before it's elevated to a standard by ISO. So it has most likely been UNC for quite a while.

Let's change it to M6, just to make everything now existing obsolete in a blow!

I have a copy of ISO 1222:2003 and the thread is specified the same (1/4-20 UNC or 3/8-16 UNC thread) as the 2010 edition. I don't have anything earlier than the 2003 edition.

We are going to metric this side of the pond but we are doing it inch by inch.

John from PA wrote in post #16298759
We are going to metric this side of the pond but we are doing it inch by inch.

Love that...

Another...

If the good Lord intended us to be on a metric system, he would have had 10 disciples, not 12.

John from PA wrote in post #16298759
We are going to metric this side of the pond but we are doing it inch by inch.

I think it has slowed down beyond that, unfortunately.

But since mankind created gods to have something to blame, the reference to god above seems appropriate.