Max Sync speed of Elinchrom Skyports

PacAce wrote in post #9742410
Skip, just as an FYI, when used with the PW MiniTT1 or FlexTT5, the Canon Speedlite flashes do, in fact, operate in HyperSync mode between 1/250 and 1/400 by default although that range can be changed.

As for it's practicality, HyperSync does allow you to use at least a stop faster shutter speed, e.g. 1/500, than would be possible without it, and with less than a stop loss of light from the flash. Using the normal HSS, as soon as the shutter speed is set to 1/320 on the camera, you would immediately lose 2 stops of light from the flash and at 1/500, you'd lose 3 stops of light. I think it's a no brainer that HyperSync at 1/500 would be much more desirable, and hence more practical, than HSS at 1/500.

I do agree that HyperSync may not be practical at all shutter speeds above max sync speed but it can be very useful at shutter speeds between 1/250 and 1/650 (maybe faster) depending on the camera and the flash or strobe used.

Interesting. Thanks.

I thought I was getting clean frames at 1/200 with D-Lites and Skyports on my 5D MKII but I discovered I was wrong. I'm safe at 1/160 but rarely even shoot that fast in studio. I was using 1/125 but lately I'm shooting at 1/100.

Mark

I'm a bit confused (so what else is new?) on two counts here.

First, I always thought studio strobes could synch to the camera's maximum synch speed. Obviously I'm wrong. I've used my strobes as the sole source of light when shooting wrestling (and I know that because if the strobe didn't fire the frame was black) at 1/250th and although I can't say I examined the entire frame with a fine tooth-comb, I saw no darkening anywhere.

On the other hand, when I accidentally knocked the shutter speed to 1/320, I obviously saw curtain across the bottom, thus rendering most of those shots unusable.

As to faster synch speeds, if a studio strobe, or my Quadra, for instance, which in socket B has a flash duration, I think, of 1/6000th of a second, why would there ever be a need for more? Isn't the flash duration (if no ambient) basically the equivalent of a super fast shutter speed?

Thanks,
Mark

The issue is that the processing required in an RF system introduces a VERY brief latency (delay) in to the system. e.g. electrical signal (to fire) -> RF pulse -> translation back to electrical signal -> fire. It's a bloody fast process, but just not quite fast enough. The effect will vary by camera max sync, radio system used, etc. RF usage usually requires a slight shave off the top as it were. Using a sync cable (aargh) will give you max sync as it cuts out the RF processing and transmission part of the equation. It's just a simple mechanical switch at that juncture.

As you say, the defacto faster shutter speed effect of a fast flash duration is very dependent on what ambient exists. If you're shooting in a room that 1/200th & F_ will turn black, you're cooking. Other than the slow sync of focal plane cameras (e.g. an SLR) can pose challenges...

A short flash duration does allow for motion stoppage as it acts like a defacto faster shutter, allowing you to drag the shutter in lower light, etc as well. However, it does nothing to control ambient. The flash may only have a t=0.5 time of 1/6000 (to keep things simple) but the shutter is still open for a relatively "long" 1/200th (as an example).

Simplistic, but think of it this way:

With a t=0.5 duration of 1/6000 (0.00017 sec), the real motion-stopping duration * (t=0.1) of the strobe is more like 1/2000 (0.0005 sec). A shutter speed of 1/200 = 0.005 sec. So during that 0.005 sec the shutter is open, the flash 'controls' the scene for 0.0005 sec or 10% of it, the other 0.0045 sec the shutter is open (0.005-0.0005 sec) and allowing "in" any ambient light (plus the light from the 'tail' of your strobe pulse - think bell curve). You can you stop down to cut the effect of ambient, but this in turn requires more flash power (if available) thus dropping duration in some strobes, stretches recycle times, opens DoF, might bump you into diffraction territory, etc, etc.

Faster sync speed, as with a leaf shutter system like say a Hasselblad (1/800 sync) allows you to better wrestle ambient light into submission when using flash. It allows the use of wider apertures in brighter conditions for shallow DoF, to better underexpose a background in daylight/studio, better balance daylight with flash without nuking the area with lights or opening DoF, etc. Fashion photogs love fast sync from leaf shutter systems for these reasons.

* This pdf from Bron (starting page 9) does a great job discussing t=0.5 vs effective t=0.1 flash duration for anyone interested - followed by a lot of nice lighting gear porn ;>

http://www.bron.ch/_da​ta/bc_do_bs_sys09_en.p​df

As Conner points out, the weak link is the RF triggers. If I plug a sync cable into my camera and my D-Lites, I can easily get a clean frame at 1/200, the max sync speed of my 5D Mark II.

Mark

Mark Booth wrote in post #9745686
As Conner points out, the weak link is the RF triggers. If I plug a sync cable into my camera and my D-Lites, I can easily get a clean frame at 1/200, the max sync speed of my 5D Mark II.

Mark

Yes but that's not always the case Mark. My D700 has a max sync speed of 1/250s and using a sync cord I can not get a completely clean frame on RX series strobes.

Typically, the max shutter sync speed is the max speed (without HSS) that you can sync a Canon body with a Canon Speedlite or a Nikon body with a Nikon Speedlight. In many cases you won't get those same speeds out of a studio strobe.

Given that leaf shutter users get clean frames with a wide variety of studio strobes as high as 1/800 some of that may come down to simple variations between camera bodies in stated (spec) vs actual shutter timing control, etc. It wouldn't take much of a variation in stated vs real spec to go outside a clean frame at max sync with any given SLR.

Conner999 wrote in post #9745903
Given that leaf shutter users get clean frames with a wide variety of studio strobes as high as 1/800 some of that may come down to simple variations between camera bodies in stated (spec) vs actual shutter timing control, etc. It wouldn't take much of a variation in stated vs real spec to go outside a clean frame at max sync with any given SLR.

Absolutely, and that is where the mechanics and physics come in to play. To date, I haven't seen anyone with a DSLR, Elinchrom strobes and radio triggers get a clean 1/250s.

TMR Design wrote in post #9745849
My D700 has a max sync speed of 1/250s and using a sync cord I can not get a completely clean frame on RX series strobes.

Well don't blame me because you bought Nikon!

Just kidding!

Mark

Mark Booth wrote in post #9745955
Well don't blame me because you bought Nikon!

Just kidding!

Mark

LOLOL It's not a Nikon issue Mark. I could remove Nikon D700 and and replace it with Canon 5D MkII. Same thing except the Canon has a 1/3 slower sync speed.

TMR Design wrote in post #9745943
Absolutely, and that is where the mechanics and physics come in to play. To date, I haven't seen anyone with a DSLR, Elinchrom strobes and radio triggers get a clean 1/250s.

Can you give me a simple way of testing that? I'd like to try it.

Thank you.

mark

MDJAK wrote in post #9746071
Can you give me a simple way of testing that? I'd like to try it.

Thank you.

mark

HI Mark,

The best way to test for the maximum sync speed of your system is to do the following:

Use a very light or white wall or white surface. Set up your trigger and strobe as you normally do, switch to MF, open up the lens, expose so the white surface is rendered white. Exposure isn't critical so you can blow out the background or go into clipping without any worries.

Start at 1/125s. Take a shot. Then increase the shutter speed 1/3 stop at a time and take the same test shot. At about 1/250s you're going to start to see the black band, which is the shutter curtain. As you increase the speed more the band will grow. If you back off the shutter speed by 1/3 stop and go to 1/200s you may get a clean frame or you may see the slightest hint of a gradation creeping in to the frame. I've determined that in most cases I can use 1/200s but 1/250 is unusable except for outdoor work where that band is concealed by other dark objects or areas in shadow.

Conner999 wrote in post #9745903
Given that leaf shutter users get clean frames with a wide variety of studio strobes as high as 1/800 some of that may come down to simple variations between camera bodies in stated (spec) vs actual shutter timing control, etc. It wouldn't take much of a variation in stated vs real spec to go outside a clean frame at max sync with any given SLR.

There's a big difference between the way a leaf shutter works and the way a focal plane shutter works. With a leaf shutter, the complete sensor (or film) is always exposed to light no matter how big or small the shutter is open. That is not the case with a focal plane shutter except at shutter speeds below max sync speed.

At max sync speed, the 2nd curtain starts to close as soon as the 1st curtain is fully open, which is when the trigger sync signal is sent to the flash or strobe to fire. It takes a certain amount of time for a strobe to go from 0 output to max output and during that time the 2nd curtain will be closing. If the strobe doesn't reach max output quickly enough, that will be evident as a dark edge on the frame. This doesn't usually happen with hotshoe flashes because they are quicker to trigger then strobes are.

But having said that, it is also true, as you stated, that variations in actual shutter speed could affect how much darkening one gets along the edge of the frame.

Another thing to consider is the actual flash duration of the strobe which could also cause a darkening along the edge of the frame. With most strobes, the lower the power, the longer the flash duration becomes. If the power level is set low enough that the duration of the flash is much longer than the length of time the shutters are open, you will get uneven lighting across the frame. The same thing will happen with leaf shutters except that you won't get the uneveness across the frame, just an underexpose of the whole frame.

TMR Design wrote in post #9745943
Absolutely, and that is where the mechanics and physics come in to play. To date, I haven't seen anyone with a DSLR, Elinchrom strobes and radio triggers get a clean 1/250s.

Robert, below is a composite of frames shot with one of my cameras using a sync cable, PW Plus remotes and Skyport remotes. Can you tell me which of the frames shown in the composite would NOT be considered CLEAN in your book, please?

To make it easier to compare the frames against each other, I laid them out vertically and horizontally. In other words, every frame has a unique reference number so those with the same number are the same frame, just duplicated.

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Good description of /point on the inherent design advantage of leaf vs focal re: sync speeds.