Flash sync speed and the 1Ds Mk II

[achee]

I've shot with the studio lights and a 50D before, and I've shot with speedlights and the 1Ds MkII before, but I just did a shoot with the 1Ds MkII and studio lights...

... and I noticed that at a shutter speed of 1/250 I was seeing the rear curtain.

So I just had a look in my manual and behold:

The EOS-1Ds Mark II can synchronize with compact, non-Canon flash units at 1/250 sec. or slower speeds. With large studio flash, the sync speed is 1/125 sec. or slower. Be sure to test the flash to see if it synchronizes properly with the camera.

Hmmm... I didn't know that before! Any idea why this is the case? Do large studio flash units take longer to fire??

PS: While searching, I noticed 'high-speed sync,' then read all about it here: http://www.ausphotography.net.au/for...nc-Flash-Canon - great stuff, I've got to try that!

[agb]

My 7D manual states that for compact flash units the sync speed is 1/250th sec, but for large studio flash units the flash duration is longer and the sync speed should be 1/60 of 1/30.

[jjphoto]

I've shot with the studio lights and a 50D before, and I've shot with speedlights and the 1Ds MkII before, but I just did a shoot with the 1Ds MkII and studio lights...

... and I noticed that at a shutter speed of 1/250 I was seeing the rear curtain.

So I just had a look in my manual and behold:

The EOS-1Ds Mark II can synchronize with compact, non-Canon flash units at 1/250 sec. or slower speeds. With large studio flash, the sync speed is 1/125 sec. or slower. Be sure to test the flash to see if it synchronizes properly with the camera.

Hmmm... I didn't know that before! Any idea why this is the case? Do large studio flash units take longer to fire??

PS: While searching, I noticed 'high-speed sync,' then read all about it here: http://www.ausphotography.net.au/for...nc-Flash-Canon - great stuff, I've got to try that!

Small flashes, speedlights etc, use a different electronic design (principal) to most (not all) large studio strobes so the delays can be different.

JJ

[achee]

My 7D manual states that for compact flash units the sync speed is 1/250th sec, but for large studio flash units the flash duration is longer and the sync speed should be 1/60 of 1/30.

WOW, are you sure? That's really really slow, that would make it impossible to shoot many types of studio scenes with a 7D!

[achee]

Small flashes, speedlights etc, use a different electronic design (principal) to most (not all) large studio strobes so the delays can be different.

JJ

Those lights worked fine with my 50D at 1/250.

[andylo]

For the studio light, maybe it's depends it is a A/S head?

I know A head has stronger punch with much less duration.

[agb]

WOW, are you sure? That's really really slow, that would make it impossible to shoot many types of studio scenes with a 7D!

Well it should read 1/60th OR 1/30th but that does not really change the meaning much. Page 130 of the manual. I was reading it last night because I am going to a portrait workshop tomorrow where we will be using studio flashes.

[kiwi]

High speed sync aint going to help you with studio strobes I dont think, they are'nt designed for that. I may be wrong

Re the sync speed, dont forget that it's the duration of the flash that freezes motion, not the shutter speed, so a lower shutter speed isnt necessarily a huge problem depending on the balance of ambient. Still, I wouldnt want to be shooting at 1/60s or slower either

[I @ M]

How much motion are you trying to "freeze"?

Typically I use 1/125 to 1/160 with monoblocs but those speeds with longish flash duration ( cheap lights ) won't stop motion perfectly cleanly and after taking delivery of some new pocket wizards a week or so ago I can shoot shutter curtain shadow free at 1/800.

[achee]

Well it should read 1/60th OR 1/30th but that does not really change the meaning much.

Yeah, I understood what you meant.

High speed sync aint going to help you with studio strobes I dont think, they are'nt designed for that. I may be wrong

I think you're right, the CANON manual only mentions high speed sync working with CANON EX speedlights.

Re the sync speed, dont forget that it's the duration of the flash that freezes motion, not the shutter speed, so a lower shutter speed isnt necessarily a huge problem depending on the balance of ambient. Still, I wouldnt want to be shooting at 1/60s or slower either

Yes, AFAIK flash durations only last 1/x,000 of a second.... or something like that... I heard somewhere... But there is usually some ambient light, so 1/60th or 1/30th of a second is going to be somewhat limiting to say the least.

after taking delivery of some new pocket wizards a week or so ago I can shoot shutter curtain shadow free at 1/800

Wow, that's cool! Pardon my ignorance, but how does the wireless transmitter increase your shutter sync speed?? I've only ever used a fairly cheap Chinese transmitter with speedlights and the OEM transmitter that came with my Elinchrom lights.

[I @ M]

Wow, that's cool! Pardon my ignorance, but how does the wireless transmitter increase your shutter sync speed?? I've only ever used a fairly cheap Chinese transmitter with speedlights and the OEM transmitter that came with my Elinchrom lights.

The pocket wizard miniTT1 transmitters and flexTT5 transceivers have been out for a while in Canon mounts and are reasonably new on the market in Nikon mount.
They allow full wireless control of both speedlights with TTL metering capability and wireless control of studio monoblocs.
The actuation of them is fine tunable from a pc / mac to alter the time that the transmitter fires the flash in relation to when a "dumb" trigger would fire it to overcome curtain shadowing.
They aren't cheap but they do work.

[kiwi]

I still dont get how they beat the shutter curtain speed...but...this stuff often does my head in

[I @ M]

...but...this stuff often does my head in

Same here.

I spent a few hours trying to decipher the on line manuals and video tutorials and then set to experimenting with the utility program that allows you to tune when the flash occurs in relation to your camera and particular lights.

I still don't know how it works but I have the pictures to prove it does.

[kiwi]

I wonder if it works like high speed sync and pulses the light "around" the shutter

[I @ M]

I wonder if it works like high speed sync and pulses the light "around" the shutter

No, definitely not in the case of studio monoblocs, they have no facility to do that AFAIK.

Anyway, a couple of pics as proof.

ISO 200 1/125 F/8 The level of ambient light is clearly seen through the window to the house under construction over the road.



ISO 200 1/800 F/8

[kiwi]

i dunno. My brain hurts.

[kiwi]

I just read an interesting article that said that the reason studio lights sync speeds are lower than say flash or the camera sync speed is caused by the time taken to trigger the studio light using a radio trigger, makes sense to my brain then that the cheaper the trigger the longer the trigger delay and therefore the slower the sync speed, id guess therefore if you use cable or high end triggers such as pocket wizards then this delay is minimal

[I @ M]

Darren, it is a combination of factors apparently.

And in Nikon particular terms it revolves around ---

Shutter type.
Cameras like the D50 where the shutter actuation involves opening the curtains but also switching the sensor on and off to achieve the correct time for exposure work quite fine at highish speeds. 1/500 is the standard synch speed.

The ability of the camera to "know" that it has a flash ( or trigger ) attached to it.
Once again, the D50 is one such camera that purely activates a wireless trigger through the "dumb" centre contact and none of the inbuilt delay causing software comes into play.

It seems that most cameras have their software set to cause a slight delay between shutter actuation and triggering of a flash signal purely to avoid the shutter curtain shadow problems, both 1st and 2nd curtain and in keeping with what the manufacturer wanted they work well.
Speedlights generally have a very short flash duration and that is why, in combination with the ability to pulse light emissions starting before the 1st curtain opens and ending slightly after the 2nd curtain closes they manage an even spread of light at high shutter speeds.
That is the secret sauce in their firmware / software that works ever so well regardless of camera brand but seems to work best with an OEM flash unit.
When it comes to studio strobes, and I think in particular the cheaper brands, the flash duration is longer but generally much more powerful than a speedlight.
This is where the "dumb" radio triggers fail, they only transmit to the strobe at the time the camera tells them to and due to the built in delay / advance in the camera software they don't get the timing correct.
Pocket Wizard have built their triggers with software that can be fine tuned by their pc / mac utility that allows you to alter the trigger activation time to cancel either 1st or 2nd curtain shadow. Their website and associated guides and videos can be a bit hard to follow but after going through them a few times certain things start to make sense and that is with studio strobes their products work best with lights that have a long flash duration at full power.

Dunno how they did it all but it works.