Originally posted by AdrianM I guess I am not really understanding some of the statements made about Pentax synch speed in this thread, and particularly the one about Pentax doesn't "even allow a flash to be triggered at speeds faster than 1/180". This is a general statement that I am pretty sure isn't actually correct.
It's 99% correct, my old film KX allows me to trigger the flash at any speed, but the max sync is 1/60. Any faster than that and I will start to get black bars in my shot from the curtains blocking the film. I'm sure most of the other manual focus film Pentax cameras allow this too. Now I have a PZ-1p, which is a very advanced film camera, and on it, the max sync speed is 1/250th, still slower than I'd like, but half a stop faster than 1/180th. It will not allow my to fire the flash at above-sync speeds.
But as for Pentax DSLRs, you cannot fire the flash in normal mode at speeds above max sync, period.Try it yourself, in Manual or Shutter priority, set your shutter speed to 1/250th, now engage the pop up flash. Notice anything? You shutter speed has dropped to 1/180th.
"I'll fix that," you say, "I'll use my PC socket as David Hobby suggests in this article:
Strobist: Hacking Your Camera's Sync Speed, Pt. 2, so the camera won't know there's a flash attached." Well if you shot Nikon, you'd be on to something. The camera can't sense the presence of a flash on the hotshoe, and so it doesn't limit the shutter speed, nice huh? But the engineers at Pentax in their infinite wisdom sought to protect us from those nasty back bars at all costs, so if you perform the same test as above, but with the flash hooked to the PC socket, you'll notice that 1) your shutter speed won't be limited by the camera anymore, and 2) the flash still won't fire. There must be a command in the firmware that either limits the shutter speed, or disables all sync commands above max sync speed.
The same is true of an external speedlight on the hotshoe. It will limit the shutter speed if it detects a Pentax-dedicated flash on the shoe, but if you attach a non-dedicated flash, or say put electrical tape over the pTTL contacts leaving the center pin exposed, the camera will simply disable the sync commands, but the result will be the same - No flash above max sync.
The only way around it is to use a high speed sync capable flash on the hotshoe (or use another brand). The camera must check to see if there is a HSS flash, and if there is, it will allow you to increase your shutter speed. But, as soon as you cross into HSS territory, the maximum power of your flash drops by two stops (at least, and this is tested on a $400 top-of-the-line flash unit). Basically that means that if you would have been able to get the shot a 1/4 power at 1/180th, but you wanted the background a little darker, then HSS is a viable option. But if you were at half or full power in normal flash mode, say for a late afternoon portrait with the sun over your subject's shoulder, HSS will not save you, your subject will be too dark. Oh, and if you want to work with your speed light off camera, you have to have a second speedlight on the hotshoe, or HSS will not function for the reasons discussed above.
It's a flawed system, but not everyone uses those features, and so many may not know about the limitation. Outdoor portrait photographers know for sure. Sports photographers know. Probably most wedding photographers know if they've ever tried to shoot the bride outdoors or in front of a window with a speedlight. Those are really important segments of the professional market, and Pentax needs to realize that they are just bleeding away serious customers (or not picking them up in the first place). Pentax needs to increase the max sync speed, either by using more robust albeit slightly more expensive shutters, or by going to a leaf shutter system in their professional lenses. And they need to allow users to disable "black bar protection" via the custom function menu.