Canon 600 HSS and back?

I read somewhere that the 600 ex rt when put into HSS will automatically go to regular sync when the shutter speed needed is lower, and then back to HSS when needed as long as you don’t turn the flash off. Like going from outside to inside and then back outside again. I looked all over the net and the manual to find it again but I didn’t see anything re: that. That would mean the flash power would go back to normal and then diminish when in HSS. Was I just imagining that or does someone else have the same experience. (When I get home I will check it)
Thanks!

Yes, most of the time, when HSS is enabled, it will only be actually enacted when the Shutter Speed exceeds the max sync speed of the camera body in question. i.e.: at or below max sync speed, HSS will not actually be applied, even when left set at enabled - so saving flash power/range, when it 'should'.

However there are exceptions! The most well known exception applied with the Canon 5Dc and 5D2. With these bodies there was a bug/quirk in that they enacted HSS (complete with power/range loss) AT the max sync speed - not just when it was exceeded. The 5DIII & later sorted this problem. There are some similar fails with some particular combinations of (supposedly HSS capable) radio triggers in the mix. The 7D (orig.) even had a similar bug when Flash mode was set to M. It's best to verify for yourself exactly what is going on AT your body's max sync speed (you don't want your Speedlite cells running down X5 quicker, than normal, when HSS is not really required).

thanks for the reply and info! i thought i came across that. I will check with my 6D body as i shoot a lot of OCF with another 600 and soon with a trigger and the 580ex2 (Yonguno ex receiver, dont remember exact name). BUT isnt the opposite happening during hss, the power diminishes to keep up with higher speed shooting? So the problem if it remained in HSS during regular shutter speeds is underexposure, correct? so HSS actually uses less power?
thanks for the verification!

pictureperf wrote in post #18466718
BUT isnt the opposite happening during hss, the power diminishes to keep up with higher speed shooting? So the problem if it remained in HSS during regular shutter speeds is underexposure, correct? so HSS actually uses less power?
thanks for the verification!

No (if I understand you correctly).

HSS is 'hard work' for the Speedlite. Partly, because it forces the unit to emulate a continuous light by pulsing @ c50KHz (albeit just for very roughly 1/120th sec) which is inefficient for a flash unit. And partly because of timing issues and the moving slit inherent to an FP shutter operating above its max sync speed. The HSS burst of pulses has to start before the first curtain starts to move - & - it terminates only after the second curtain has completed its travel.

So under HSS flash power/range are reduced, perhaps 2 stops or more and the batteries deplete cX5 times faster. Cheers

Yes thats right i forgot about the pulse from the flash and the FP shutter. You are correct.