Originally posted by GoldenWreckedAngle The 50D and a the D300 both fire their flash in rear curtain sync at their regular front curtain sync speed and you can freely exceed that speed and still get an uneven flash exposure if you want to, and by George, I want to
. I don't know if they just auto switch to front curtain above a certain speed or what but the flash fires and nobody has to access a menu and change a setting to make it happen.
I've read on the blogs of several of the top professionals in both brands that they recommend setting the flash to rear curtain and leaving it there. Not a recommendation I can follow as a Pentax shooter.
No, that because Pentax doesnt work the same way.
Sync mode is set on camera with Nikon/Canon bodies and flashes. Thats why its not supported on the Sigma flash either. Most Nikon and Canon bodies have a default "Auto HS" feature which automatically switches to HS mode if you exceed the sync speed.
Hence you can indeed set the camera to Rear Sync, and leave it there, but only because it will automatically switch to HS. So the pros advice is correct - if you use a Nikon or Canon in auto HS mode.
With Pentax, if you use a Pentax flash you can set sync mode ON THE FLASH. This makes is much easier to change (one slider click) and if you set it to HSS, it will automatically revert to normal sync when you drop the speed below 1/180. So the advice is simply different, but the effect is the same. If you really want trailing curtain, its a single click away.
With a dedicated flash, you would have the SAME RESTRICTION with any system. The camera will sense the flash type and switch it accordingly at the appropriate speed. (I believe this is indeed HALF the speed for rear sync for reasons explained above on any system).
However in your friends video, he used a non-dedicated Quantaray flash and a wireless transmitter. The camera cannot communicate with the flash (one pin) so does not know its restricted. However because Auto HS is set on the camera, you can set the shutter speed as high as you like with a radio trigger - the camera will probably assume its in HSS mode and simply fire anyway, triggering the radio transmitter. However it will fire once in Leading Sync mode because there are no pins to detect the trailing curtain or HS command.
This would be really annoying in a studio with no ambient. Thankyou Pentax.
On the K7 HSS is not supported on camera, so the hotshoe is cold above 1/180. Might work on an *istD though.
As for the 40D, this is pure luck I would say. A happy list of circumstances rather than a design feature, and it does not work on Pentax and I have no idea if it works on any other Canon or even a Nikon. You'd have to ask.
I really cannot get excited about that. For a wedding I simply set the flash to HSS and let it do its stuff. Besides, if you DO have HSS mode (the Quantaray does not) you dont really NEED to do this, at least not in the circumstances described in the video. A second HSS flash will do pretty well too placed near the model. You will get very similar effects with wide angle lenses.
Nor quite frankly would I ever use Trailing Curtain sync flash to freeze motion. Slow sync modes never were for freezing motion.
If I want to freeze motion and its very bright, the ambient will be so strong the flash will have limited effect and you may as well use a fast shutter and HSS to provide fill. If its very dark, the flash will freeze it even if the shutter speed is quite low.
1/180 is hardly a serious restriction if the only other option is 1/250. You should also commiserate with Canon 5D users (and mk2) who are limited to 1/200.
Pentax dont work quite the same way as Nikon or Canon (nor do Sony or Oly BTW) so instead of slavishly following pro advice aimed at the wrong camera, you will just have to work it out for yourself.