H4D - Profoto Synch

[Bruce MacNeil]

Hi,

I am testing an H4D in consideration of a purchase. I now use Canon and am happy except for a few things.

So, the 1/800 synch on the H4D is attractive. But, the camera and my profoto seem to lose about a half stop between 1/500 and 1/800. Is this normal?

BTW - Profoto D1's with air synch and the B3 packs with Air synch.


Thanks - B

[colinm]

I haven't tested with the H4D specifically, but in the general sense, the answer's yes.

The key to Hasselblad's marketing materials about flash sync—and even more to Phase/Mamiya's "amazing" 1/1600 sync—are those two horrible little words up to.

All the planets have to align for perfect synchronization between flash and camera at those speeds. If the flash duration is longer than the shutter speed, you'll lose light. (And at lower power settings on the D1s in particular, you're likely to be pushing up against that.) If the exposure beginning doesn't perfectly align with the flash firing, you'll lose light. If the radio delay is too long, you'll lose light. Add all of those together and synchronization at fast shutter speeds is a small miracle.

If you haven't already, try putting the Air Remote into Fast Mode. If you haven't been using it, this may help at least to some extent. But outside of the world of brochures, the "up to" is much more reliable than the "1/800" or "1/1600."

[Bruce MacNeil]

I haven't tested with the H4D specifically, but in the general sense, the answer's yes.

The key to Hasselblad's marketing materials about flash sync—and even more to Phase/Mamiya's "amazing" 1/1600 sync—are those two horrible little words up to.

All the planets have to align for perfect synchronization between flash and camera at those speeds. If the flash duration is longer than the shutter speed, you'll lose light. (And at lower power settings on the D1s in particular, you're likely to be pushing up against that.) If the exposure beginning doesn't perfectly align with the flash firing, you'll lose light. If the radio delay is too long, you'll lose light. Add all of those together and synchronization at fast shutter speeds is a small miracle.

If you haven't already, try putting the Air Remote into Fast Mode. If you haven't been using it, this may help at least to some extent. But outside of the world of brochures, the "up to" is much more reliable than the "1/800" or "1/1600."

Hi, thanks for the advice.  Further testing: I tried the 'high speed mode' on the Air controller and that made no difference. It appears that a full f-stop is lost between 1/500 and 1/800 strobe wise.

In a practical sense this is OK for me because I am generally looking for more wide open shooting outside with minimal fuss. And, generally the packs are dialed back a few stops when outside. SO, I have a few stops to dial back up and the extra shutter speed gives me another stop of openness on the lens.

Life's usual rule of compromise and expense perseveres.

[Conner999]

As Colin mentioned, it will be an additive chain of issues such as the delay that is intrinsic in most radio systems, any deviations from 'perfect' ideal spec with the camera, radio, light chain of hardware and duration.

As example, the flash duration of the D1 1000 ( to pick one model) at max power is a t0.5 time (point at which 50% of the flash pulse has been emitted) of 1/1800.  Sound impressive, but the more telling is the t0.1 time or the point where 90% of the pulse has been emitted which would be roughly 1/3rd of the t0.5 time, or 1/600 of a sec. Right away at max power at 1/800 sync with the D1 1000 you're giving up power (as in not capturing 10% of the flash pulse emitted) - just from flash duration alone, everything else being perfect (which it won't be). The 'issue' that will only get worse as you dial a monolight down and duration starts to stretch. Add in any radio delay (as small as it may be), etc and that 10% of the pulse 'left on the table' can be much higher. 

If you try a test of AiR and using a sync cable to trip the strobess at the same power you'll be able to at least tell, what if anything, the radio sync may be costing you. 

[Doug Peterson]

The key to Hasselblad's marketing materials about flash sync—and even more to Phase/Mamiya's "amazing" 1/1600 sync—are those two horrible little words up to.

All the planets have to align for perfect synchronization between flash and camera at those speeds. If the flash duration is longer than the shutter speed, you'll lose light. (And at lower power settings on the D1s in particular, you're likely to be pushing up against that.) If the exposure beginning doesn't perfectly align with the flash firing, you'll lose light. If the radio delay is too long, you'll lose light. Add all of those together and synchronization at fast shutter speeds is a small miracle.

With a Phase One DF with a V-grip Air (which has a built in air transmitter) and Schneider LS lens the flash can in fact sync without light loss at 1/1600th.

As you say you do have to be aware of other factors like flash duration, but e.g. a D1 Air 500 has a flash duration of around 1/1600 starting at one stop from max, so full power from the flash would be seen except at max power at which point nothing bad happens - you just don't see as much light from the strobes as you expect, requiring you to change your metering to in-camera metering (e.g. histogram) rather than a flash meter.

As another reference point the top-grade Profoto gear, Pro-8, have a worst-case flash duration of 1/1600 so can be used at full power synced wirelessly (using the built-in transmitter) at 1/1600 without any loss of light.

Otherwise all the systems I've used in-practice cannot exceed 1/400th without some loss-of-light and 1/640 without significant loss of light.

Doug Peterson (e-mail Me)
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[Bernhard]

note that D1 works different than B3. It has highest flash duration at full power but the lowest at lowest power level, it's the opposite with B2/B3

I measured the D1 and couldn't get the 500 head better than 1/650 t0.1 (note Profoto use t0.5) measured with Broncolor meter

Shouldn't we be reading t0.1 instead of t0.5?

which D1 are you using Bruce?

Bernhard Kristinn

[UlfKrentz]

snip

As another reference point the top-grade Profoto gear, Pro-8, have a worst-case flash duration of 1/1600 so can be used at full power synced wirelessly (using the built-in transmitter) at 1/1600 without any loss of light.

snip

Wow! But I´m afraid I cannot believe it. For this the whole flash duration would have to fit in the time window of 1/1600s.
See conner999´s post regarding t0,5 and t0,1: Pro8Air 2400 fires with a 1/1600s t0,5 flash duration ->so simply refering to the specs you will use about 1 Stop when using 1/1600s shutter speed. BTW, if you are interested in a comparison of Pro7 and Pro8 flash duration, you might be surprised: http://blog.profoto-usa.com/?p=154 (Pro8 softly begins to get shorter below 1/8 power and significantly shorter below 1/32 power, from 1/8 power to max they are extremely close).

To the OP, most studio lighting equipment will have a quite long flash duration. Using an extremely short shutter speed will cut an amount of your flash energy. Using radio transmitters will add some delay, making things worse. So you loose some light but in the end you are able to use a short shutter speed with strobes.

Cheers, Ulf

[Bruce MacNeil]

which D1 are you using Bruce?

Bernhard Kristinn

I have the D1 500's. AMple power for my Canon location portrait uses.

[Conner999]

So with the D500s, you've a max t0.5 power shortest duration of 1/2600, call it roughly 1/800 - just what is needed - if nothing else is adding latency, which there will be some with radio, even minuscule - as long as you operate at max. As you drop to min power, that duration stretches out to a t0.5 of 1/1000 or a real world duration of 1/333. Of course you could operate with ND gels at max power, but not an ideal solution if using a battery system for power on location.

At least with a leaf shutter you can simply adjust the exposure and/or play with gels to deal with any uncaptured light at max sync vs. having to deal with the flash capturing the shutter curtain in transit as with an SLR.

In short, there is the speed the system can, in theory, sync at and the amount of light the system can capture from your strobe at that sync - which depends on flash duration (the bigger player here I suspect).

If the OP is interested, the Broncolor system catalog avail for download from Bron (as an FYI, I shoot Profoto), has great info on duration. 

[BrendanStewart]

Also another note, Elinchrom Ranger's also have their fastest duration at the top of the power band. We use them in a bunch of our shoots with the H system and we found we lose less than a stop at most power levels.

Interestingly enough, we were told by an engineer @ Elinchrom that if you put the new speed transmitters into 'speed' mode, it will increase the speed in which they fire, and again, that's how we lose almost no light across the power band.

Lots of shots using Elinchrom system here: http://www.flickr.com/photos/symbolphotography/sets/72157624913368149/

[jorisvm]

does anyone know if Pocket Wizards loose a stop when shooting H4D at 1/800 ?