The "x" on a P shutter speed dial

[butch]

What's it for? I'm guessing it's for indexing a meter with a connected shutter speed dial like the Photomic F. But I've never seen a Canon P meter.

 

[photodog]

Oh, that's the x sync setting for flash.

 

[VictorM.]

It's the highest shutter speed that works with electronic flash. Slower speeds will work as well, but will allow even more ambient light to reach the film; sometimes an interesting technique. Faster speeds won't work, unless you like having part or all of the frame unexposed.

 

[butch]

One scribe I read said that the P synched at 1/60. Is this then a second 1/60 setting? I can't tell much difference in the sound at "x" and at 1/1000, the closest setting on the dial besides "B". Never use flash, but if the synch is 1/60, why the "x"? Just seems redundant.

 

[VictorM.]

According to the Canon Museum site, the P syncs at 1/55 sec. That's probably the x speed.

 

[John Shriver]

Because the shutter speed dial also has to throw a switch inside the camera to switch from flashbulb sync, which it provides at all other shutter speeds. So they have a dedicated setting for X. It sets the shutter speed cams at 1/60, but closes the flash sync contact when the first curtain finishes opening, rather than when it starts moving.

Canon had some nice patents on this, see US Patent, err, darn. My IV-SB2 has film in it, and the IIF only has "Patent Pending" for the US.

 

[butch]

Thanks, guys. Now it makes sense. A smart crew, around here.