Beginner Lencarta Elite Pro 2 flash duration

alexthecheese

alexthecheese

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Hi guys. I purchased a Lencarta Elite Pro 2 300w kit in the week and have been having a play since opening it up this morning. I've got a Nikon D800.

I've got a question regarding the flash duration. I can't get the flash to work on anything above 1/250th with any success. My understanding was that it does at least 1/1000th (can't remember where I read it), but I've getting only a portion of the image correctly lit when I go above 1/250.

Csmera flash setting is 1/320fp, but no luck.

Any idea? Have I bought the gear on a misunderstanding or have I not got the settings right? Cheers!
 
Flash duration is the period of time that the flash lasts, e.g. 1/1000th second.
But even that simple statement isn't all that simple, because there are primarily 2 different ways of expressing that time, there's the method that relates to the length of time it takes for 50% of the flash power to be discharged and the length of time that it takes for 90% of the flash power to be discharged, these figures are very different.

But, it seems from your question that you aren't actually talking about flash duration, you're talking about sync speed, which is the fastest speed at which a shutter can operate and still let the flash do its job.
This speed varies, typically it's around the 1/200th - 1/250th second mark, and this is dependant not on the flash but on the camera.

When using flash indoors, this doesn't really matter because the only real function of the shutter is to be open when the flash fires, the shutter doesn't control exposure and doesn't affect the ability of the flash to freeze action - the action freezing is carried out by the flash itself.

If, for some reason, you really want to use a fast shutter speed, just use a tail end sync flash trigger.

If you want to understand the basics, just go to the page that you bought the kit from and click on the "downloads" tab, which explains the basics of flash photography.
Hope this helps - I would write more but I want to watch "Spooks" :)
 
Thanks Garry. I think I need to do more reading. Is it possible to answer in not too many words (for your benefit and mine!) how the Superfast flash heads are different when the syncspeed is still going to be limited?
 
The SuperFast technology is explained here.
Basically, unlike the vast majority of flash heads, it uses Insulated-gate bipolar transistor technology. IGBT technology works in the same way with this new flash head as with hotshoe flashes, which means that the flash duration becomes progressively shorter when the power is reduced, this is the opposite of what happens with conventional flash heads. At full power, the SF300 produces 300Ws of flash power and behaves exactly like a conventional flash head, with a respectable t.1 flash duration of just 1/1600th second (roughly equivalent to a convential flash head with a stated flash duration of 1/4800th sec), this reduces to an incredible 1/20,000th second at minimum power.
The way that it does this is by firing the flash at full power, regardless of the power set on it. If the power is turned down to half, it only fires the flash for half the time, at 1/8th power it fires it for 1/8th of the time etc. A conventional flash head works differently and passes different levels of energy to the flash tube at different power settings, and because of this the flash duration becomes longer, not shorter, when power is reduced.

There is in fact a wealth of info on our website, apart from the article that I mentioned earlier. There are all sorts of tabs on every page that features tech equipment, and each tab has its own articles, explanations, Q and A's etc. There is also the jargon buster tab, and if you go to our learning centre there are a couple of hundred articles there too.
 
You need to know how a focal plane type shutter works, and why conventional flash (ie, not high-speed sync) must be used at the max x-sync speed (1/250sec on a D800) or longer. In a totally dark studio, it doesn't matter if the shutter speed is 1/250sec or ten minutes - the only exposure is the flash, and in effect, the flash duration is your shutter speed. Google just brought up this link - see the little blue graphic down the right hand side http://www.imagen-estilo.com/Articles/Flash/maximum-flash-sync-speed.html
 
That's great, thanks.

I understand how the shutter works (when it's going very fast the shutter chases itself, if you know what I mean, creating a fast slit) and now understand from your link HoppyUK that the flash duration is actually incredibly short it is why you only get a very small part of the shot exposed properly.

How do you take photos with flash with wide apertures outside on a sunny day, where you would need a high shutter speed? Is it just an impossibility?

Does the ElitePro not use IGBT, I take it?
 
alexthecheese said:
That's great, thanks.

I understand how the shutter works (when it's going very fast the shutter chases itself, if you know what I mean, creating a fast slit) and now understand from your link HoppyUK that the flash duration is actually incredibly short it is why you only get a very small part of the shot exposed properly.
Click to expand...

It's not the short duration of the flash pulse that causes part of the image to be exposed. At shutter speeds above max x-sync, you only get a small part of the image exposed because the second shutter blind has already covered over part of the sensor.

How do you take photos with flash with wide apertures outside on a sunny day, where you would need a high shutter speed? Is it just an impossibility?

Does the ElitePro not use IGBT, I take it?
Click to expand...

Options include using a neutral density filter to pull the whole exposure down and use a longer shutter speed (fine if you don't also need a fast shutter speed), or high-speed sync, or tail-sync. Both the last two options have drawbacks, too.
 
Thanks guys, I think I have it figured out. The shutter speed is only fully open (i.e. not chasing eachother) when up to 1/250th of a second. Any faster than that and before the first curtain has arrived at it's destination, the second curtain has set off. The flash duration being very small in duration, it fires and shows exactly where the curtains are in the frame. I think.

I understand that high-speed sync is where the flash fires multiple times as the shutter takes it's course. But I don't think I can use that with the ElitePro 2's, can I? Tail sync I'm not sure, unless that's the rear curtain fire when it exposes the scene and then fires the flash at the end?
 
The only flashes that can do high speed sync are those that operate on the IGBT system, and conventional flash heads, including the ElitePro, don't operate on that system.
The links that I gave you earlier explain how tail end sync works, but basically it requires a fast-moving shutter and a slow firing flash. The flash needs to fire for long enough for the shutter to complete its cycle, therefore the flash is on for the length of time that the shutter slit is moving across the sensor/film.
This allows faster shutter speeds to be used, right up to the maximum for the camera, but the faster the shutter speed, the more uneven the exposure becomes.
 
alexthecheese said:
Thanks guys, I think I have it figured out. The shutter speed is only fully open (i.e. not chasing eachother) when up to 1/250th of a second. Any faster than that and before the first curtain has arrived at it's destination, the second curtain has set off. The flash duration being very small in duration, it fires and shows exactly where the curtains are in the frame. I think.
Click to expand...

Yes (y)

I understand that high-speed sync is where the flash fires multiple times as the shutter takes it's course. But I don't think I can use that with the ElitePro 2's, can I?
Click to expand...

As Gary says, you need an IGBT-regulated flash for proper High Speed Sync (these terms often get mixed up and confused!) that can fire the flash many thousands of times second - so rapidly that it effectively becomes continuous light for as long as it takes to exhaust the capacitor. To get a good understanding of this in practise, you need to to know about shutter cycle times - that is, the total time it takes from the first curtain starting to move at the top of the frame, to when the second curtain reaches the bottom. In very round numbers, it takes about 3ms for a typical shutter blind to run from top to bottom. Here's a slo-mo video of a Canon 5D Mk2, that actually has a slightly slower cycle time than some (max x-sync speed is a very rough guide to that).
View: https://www.youtube.com/watch?v=ptfSW4eW25g
From this, it's clear that the flash must keep pulsing for at least 4-5ms at 1/1000sec shutter speed which in turn means that in terms of brightness, as the shutter blinds scan down, no part of the sensor can receive more than 1/4 of the total light (roughly). So with HSS, there is always a big drop in effective exposure, and as shutter speed rises, brightness reduces pro-rata - major drawback!

Tail sync I'm not sure, unless that's the rear curtain fire when it exposes the scene and then fires the flash at the end?
Click to expand...

Tail-sync is an old technique, dating back the use of FP flash bulbs designed to burn evenly throughout the cycle time of a focal plane shutter. With voltage-regulated electronic flash, ie most studio heads, many of them have quite long flash durations (ignore manufacturer's claims here) and are putting out usable light over a 3-5ms period (different heads vary a lot). Put 'flash durations' into google images and you'll see oscilloscope graphs where the flash rises very rapidly to a peak, and then fades gradually down the 'tail' of the curve. Tail-sync synchronises the flash so that the shutter blinds track down the frame, following the fading tail so that the whole frame receives exposure. The obvious drawback here is that brightness is both reduced and very uneven down the frame.
 
HoppyUK said:
Tail-sync is an old technique, dating back the use of FP flash bulbs designed to burn evenly throughout the cycle time of a focal plane shutter.
Click to expand...
Zeiss invented it in 1953, when the typical max sync speed of a FP shutter was just 1/30th second. Back then, the cameras that could use that technology (with the right flash bulbs) had a choice of 3 delay settings on the shutter
X - for electronic flash, which was just about becoming available
M - delay in firing the shutter to allow a "normal" flash bulb to develop its brighness
FP - delay in firing the shutter to allow a "FP" flash bulb to develop its brightness.
The FP flash bulbs were incredibly expensive*, and were basically in the shape of a Halostar modelling lamp, or if you prefer, a straight sausage. They were filled with magnesium foil and because of their length they took long enough to burn along their length to produce what was effectively a continuous light.
They burned extremely hot, and until Philips (I think) had the bright idea of coating them with a foul smelling plastic, they frequently exploded.
The flash was dazzlingly bright to the eye but produced very little real power.

In effect, electronic flash using HSS is just a more convenient, cheaper development of this, but other than that, nothing has changed because HSS still doesn't produce much used light:)
* From memory, which may be wrong, when I started using them in the early 60's they cost a day of my pay each. Mind you, I was working as a trainee photographer/apprentice for Wallace Heaton's, so a day's pay didn't amount to much:)
 
mike weeks said:
Oh but it does, your own Atom 360 will still produce twice the light of most standard flashguns in HSS mode, the issue is how it is used.

Mike
Click to expand...
But only because it has much more power than standard flashguns
 
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