Originally posted by Reed Yes. But both have lightweight non optical genuine flash triggering/master control systems- Canon -ST-R3-RT, Nikon-Su-800.
The Nikon is optical ... it just uses IR, Reed.
The Canon is not intrinsic to the Canon system - in fact, it's an exception. It works only with those RT-600EX speedlights, not anything else they or anyone else sell. It's as if it's a third party product.
Originally posted by Reed If there was genuine Pentax trigger/master controler- I would go for it..
I wouldn't wait, Reed. I have the Acon and Aokotec, they both work, the Cactus V6 II has been used by forum member @fwbigd to drive with HSS a Godox Nikon-compatible strobe, the upcoming Metz looks good.
Most Canon and Nikon owners *don't* use their own brand triggers, they use Pocket Wizards, Cowboys, Cactus, Yongnuo, etc - we're no different.
Originally posted by Reed Assume we both have two TTL strobes for example Metz52 -He will have ability to control an off-camera flash by using the pop-up flash as the wireless controller...
Optical triggers are a dead end, Reed. Rightly or wrongly, manufacturers know that this is an era of cheap radio transceivers, and that's why popup flashes are being left out of bodies or degraded in specs. It annoys me as well as you, since the Pentax system itself certainly supports a pop-up controller, it's been there on lots of other models.
We can get caught up with specific examples rather than system differences. His 750D has the pop-up commander, your K-S2 doesn't, if he had a 5D MkIII he doesn't even have an inbuilt flash, just like my K-1.