[sany]

Hi

This is the first time I am going to learn using an external flash on my Pentax K-r.
I have bought a Yongnuo YN-560 III and trying to start getting the hand of it.
I was reading about sync speed and so on... Somewhere I keep getting lost with the jargons. I spotted the following in one of the Pentax K-r reviews "sync speed is 1/180 seconds, though if an external flash that supports high speed sync is used, maximum shutter speed with flash is 1/6000 sec..". Can somebody help me understand this and how this applies to my K-r along with Yongnuo!?
Thanks in advance.
S

[OregonJim]

1/180 is the fastest shutter speed in which the shutter is fully open all at once. The shutter has two curtains. At speeds above 1/180, the second curtain starts closing before the first curtain has fully opened, so the exposure happens as a 'slit' moving across the sensor. If you fire the flash, which only lasts for 1/4000 or less, it will only light the section of the frame exposed by the slit in the shutter.

High-speed sync gets around this by firing multiple bursts from the flash as the shutter moves across the frame. The tradeoff here is that the flash is only capable of firing at a greatly reduced power level, usually 1/16 or lower.

HSS is a limited, specialized application - don't even bother with it until you're full comfortable with normal flash.

[carrrlangas]

The Yongnuo is manual flash without HSS capability (High Sync Speed). You would need a P-TTL flash (Pentax - Through The Lens (metering)) that has HSS such as Metz, Sigma or Pentax flashes. But don´t worry, 1/180 is plenty for most uses. the limits comes from the shutter mechanism in DSLRs. If you use a compact camera with flash and the optical slave mode on the yongnuo you´ll can sync at the max shutter speed of your camera, really fun.

[Bronmar]

Speed ~ 1/160. Flash will not fire if it's shorter than this.
Actual speed is controlled from your flash which has manual levels setting.

[sany]

Hi

Thanks all for suggestions.
@carrrlangas - your words '1/180 is plenty for most uses' is a real comfort as I am reading the other comments and inablity of Yongnuo YN-560 III to do this. Does this mean, that I can still freeze 'rain' shots like the ones you must have seen - night shots in rain and flash going from inside the umbrella where we see those rain drops freeze!? I am looking to play those kind of creative shots....
1. Can you also elaborate more on your last line 'If you use a compact camera with flash and the optical slave mode on the yongnuo you´ll can sync at the max shutter speed of your camera, really fun.' yes, I am looking for those kind of fun stuff.
2. How do I make the compact camera trigger and sync with my dslr to achieve that if my understanding is what you mentioned!?
3. Also can you suggest a few lines on how I can trigger the Yongnuo in slave mode to be triggered by the onboard flash ( I am asking this because I have not yet got hold of a trigger but waiting for the new one from Yongnuo awaiting launch and that I prefer to use the flash away from the DSLR body).

thanks

[carrrlangas]

Sany, at this point, this will be your best resource:
Strobist
And a great book: Light Science and Magic: An Introduction to Photographic Lighting: Fil Hunter, Steven Biver, Paul Fuqua: 9780240812250: Amazon.com: Books

@carrrlangas - your words '1/180 is plenty for most uses' is a real comfort as I am reading the other comments and inablity of Yongnuo YN-560 III to do this. Does this mean, that I can still freeze 'rain' shots like the ones you must have seen - night shots in rain and flash going from inside the umbrella where we see those rain drops freeze!? I am looking to play those kind of creative shots....

The strobist will be a treat to understand this but I´ll try: Yes, I think 1/180 would freeze rain but, the short duration of the flash (much less than 1/180, I think it´s something like 1/1000 to 1/2000) will freeze it too. So you can use a slower shutter speed (1/40 for example) to get some ambient light captured and use the flash to accentuate the rain drops or else. So you would be mixing ambient light with flash light relying on the short duration of the flash to freeze the action and using a slow shutter speed to capture the rest of the scene..

1. Can you also elaborate more on your last line 'If you use a compact camera with flash and the optical slave mode on the yongnuo you´ll can sync at the max shutter speed of your camera, really fun.' yes, I am looking for those kind of fun stuff.

Compact cameras has another type of shutter mechanism that allows much faster sync speeds than DSLRs. So you can use the pop up flash on the compact to trigger the Yongnuo flash: See the button between "MODE" and "ZOOM"?, it selects how the flash will be triggered.Press it until you see "S1" on the top row of the LCD. I think it stands for "Slave mode 1" and you´ll see a red light flashing on the front of the flash. So, when your compact cameras pop up flash fires, the Yongnuo flash will "see" it and fire itself.

2. How do I make the compact camera trigger and sync with my dslr to achieve that if my understanding is what you mentioned!?

As explained in other posts, you can´t trigger your DSLR at high shutter speeds... I meant you will be able to sync at the max shutter speed of your compact camera because they usually sync with their pop up flash at any shutter speed.

Have fun!