Lencarta Ring Flash - Max Sync Speed

Catdaddy

Catdaddy

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Chris
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Question for Garry, perhaps?

I spent a little time playing with the Lencarta Safari Ringflash last night and wanted to try and work out the highest speed I could effectively work at before shutter speed became an issue. Camera I was using was a Nikon D7000 - the fastest shutter speed is normally 1/250, but I could see the shutter curtain having an effect with the ringflash at about 1/200...

I wasn't using any radio transmitters - just a sync cable to the battery pack and then the lead from there to the ringflash head.

Somewhere on the forum, somebody said that the flash duration is effectively your maximum shutter speed. The Lencarta website says that flash duration for the Safari heads is between 1/800 and 1/1500 (I think)... Is it different for the ringflash?

And has anyone got any ideas why I can't really sync with a speed higher than 1/200?
 
Quick link on shutter speed

http://www.kenrockwell.com/tech/syncspeed.htm

As i understand it the ring is slower then the head as the flash tube is longer so you might get lag at 1/200 so depending ont he power your using you may get lag, I've not had an issue yet but then I tend to use low power for close up shots.
 
Yes, I've tried it down to 1/8th power...
 
If you mean banding in the sense of a black shadow of the shutter curtain, then that's a sync problem. But I'm guessing you mean uneven exposure top to bottom, and that's the long flash duration.

The quoted flash durations for studio flash are pretty meaningless IMHO. They refer to the t.5 time but the tube is still putting out signifcant light over a much longer time, down to the t.1 time. Rule of thumb is that t.1 is three times longer than t.5 :eek: On top of that, ring flashes have a naturally longer duration due to the length of the tube.

If you're using it for fill-in outdoors, you probably won't notice it at all, but it should be even at 1/125sec.
 
Then it's likely not the flash duration that's causing the sync problem. It's somewhere between the camera or sync cable, or the combo that's limiting the sync speed. Check with another camera/cable/trigger to see if anything resolves the problem.

Trouble shooting has to be done by a slow process of elimination, unfortunately... good luck mate. Let us know how you get on.
 
Thanks for the reply, Richard.

The 'banding' is really obvious at 1/400, and at 1/800 - forget it! At 1/200 you get all the image at a uniform brightness, so I guess there's no sync problem there, but it's noticeably darker than at 1/160 or 1/125, which are about the same...

Edit: Thanks as well, hairboy - I'll try it with my D70 too...
 
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HoppyUK said:
If you mean banding in the sense of a black shadow of the shutter curtain, then that's a sync problem. But I'm guessing you mean uneven exposure top to bottom, and that's the long flash duration.

The quoted flash durations for studio flash are pretty meaningless IMHO. They refer to the t.5 time but the tube is still putting out signifcant light over a much longer time, down to the t.1 time. Rule of thumb is that t.1 is three times longer than t.5 :eek: On top of that, ring flashes have a naturally longer duration due to the length of the tube.

If you're using it for fill-in outdoors, you probably won't notice it at all, but it should be even at 1/125sec.
Click to expand...

True, but even so, at 1/8 power, T1 still can't be as slow as 1/200, surely? Never used a Lencarta ring flash myself so can't confirm, but never heard of anyone having a huge problem with sync speed with this gear in the past.
When using it in studio, 1/200 or 1/250 means little, but for outdoor shoot, it's a big deal. I'd try to figure out the actual cause of the problem by the slow troubleshooting method, if it were me.
 
Catdaddy said:
Thanks for the reply, Richard.

The 'banding' is really obvious at 1/400, and at 1/800 - forget it! At 1/200 you get all the image at a uniform brightness, so I guess there's no sync problem there, but it's noticeably darker than at 1/160 or 1/125, which are about the same...

Edit: Thanks as well, hairboy - I'll try it with my D70 too...
Click to expand...

Yes, that's the flash duration. And the higher you go, a) the less light you'll get, and b) the more uneven it will be. To get it perfectly even, and maximum power, the shutter must be fully open for the full light dump. A typical shutter is only fully open for about 1.5ms (1/666sec) at max x-sync speed and the ringflash's t.1 time is longer than that.

What you're getting at higher speeds is the tail of the flash as it fades away. Some people call this 'hypersync' technique (not to be confused with Pocket Wizard's excellent HyperSync) and claim it's a good workaround way of getting high speed sync, but personally, I think it's rubbish :D You might get better results with the D70 though, with its trick electronic shutter.
 
Thanks! I'll get a series of plain-background images up later on with both cameras at varying speeds...
 
Here we go...

First set of images are from the D70, with its electronic shutter. The second set are from the D7000. (I forgot to set the D7000 ISO to 200 to match that of the D70, but I'm sure you get the idea...)

D70:
D70-Ringflash-Test.jpg


D7000:
D7000-Ringflash-Test.jpg
 
I'm not sure why you seem to think that you shouldn't get a band at shutter speeds above the maximum sync speed when not using HS flash mode. That's why it's called the maximum sync speed.

The main issue is that the exposure is not fully even at either 1/250 or even 1/200 second but this is not uncommon with relatively slow flash heads, personally I would probably use 1/125 sec when using the ringflash on that camera.
 
Thanks, Ed - that's why I was asking what the flash time is for the ringflash - if it was in the region of 1/800 (or even 1/500) then I wouldn't necessarily expect to see any ill effects as soon as 1/250... but if ringflashes are generally slower than flash heads, then I guess it makes sense...
 
Catdaddy said:
Here we go...

<snip>
Click to expand...

Now I see what you mean. That's pretty much exactly what you'd expect, as Ed says, though it's interesting the loss of light at 1/500sec on the Nikon - because the long duration means you're not capturing the full flash output, whereas you would with a normal hot shoe gun.

The banding on the D700 over 1/250sec is the shading of the second curtain, which has started to close before the first curtain has reached the bottom (image is inverted on the sensor). Ie, the sensor is never fully uncovered above 1/250sec, hence that's the x-sync ceiling.

It should normally be 100% clean at 1/250sec, as it would be with a hot shoe gun, which I suspect is a delay quirk inherant to the ring flash.

If you can hack it to pick up the high speed sync trigger (FP flash) that would give some interesting results above 1/250sec. That's the tail-sync hack, but you need another gun and an optical slave rigmarole to extract the firing signal.
 
Flash duration is long because the flash tube is physically long, that's unavoidable with ring flash.

But that isn't the problem here, the problem is that you're asking the camera to do something that it simply can't do - you're asking it to have it's shutter fully open at a shutter speed higher than the maximum sync speed for flash.

There seems to be some kind of triggering delay with your D7000 that really shouldn't exist with your direct connection via synch lead, it isn't there with the D70 examples so it clearly isn't the ringflash or the synch cable that's causing it.
 
Thanks Garry... Would the difference have anything to do with the different types of shutter between the D70 and D7000? (D70 is mechanical and electronic; D7000 is focal plane)

Edit - bit of an update... I've just been connecting via my SB-800 with Auto-FP on and the results I'm getting are more akin to the D70 now - as long as the SB-800 is switched on... Previously, I'd been connecting via a simple hotshoe adaptor... Does this mean I need to invest in some kind of hotshoe adaptor that can cope with Auto-FP?

I'm not quite sure I understand why it's doing that - the ringflash obviously doesn't support Auto-FP, and the SB-800 is set to 1/128, pointing behind me and covered in a black cloth, so it's not going to have any effect at all...
 
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Catdaddy said:
Thanks Garry... Would the difference have anything to do with the different types of shutter between the D70 and D7000? (D70 is mechanical and electronic; D7000 is focal plane)
Click to expand...
Absolutely
D7000 is a standard shutter affair, whereas the D70, D70s, D50 and D40 all have a mechanical/electronic hybrid affair
 
Thanks Michael... I'd just edited my post before you replied... can you offer any advice re a hotshoe adaptor that can handle Auto-FP? (If such a thing exists!)
 
When you say hotshoe adaptor, are you talking about taking the speedlight off camera?
A good hotshoe extension cord would do it, or look at the new generation Phottix stuff about to launch ( the "Odin" kit), although I believe the Canon version will be first.
 
Something that will allow me to do what I just managed, but without the need to have my speedlight mounted and switched on all the time:

With the SB-800 set to Manual and 1/128, but with Auto-FP switched on, I was getting fairly even exposure by connecting the Safari to the speedlight's pc sync socket. But the SB800 has to be on to do that - when it's switched off, I'm getting the same results as I originally got, regardless of whether Auto-FP is set on the D7000 or not... (If that makes any sense!)
 
Here's what it's giving me... As I say, SB-800 set to manual 1/128 and mounted onto a D7000, AutoFP switched on, Safari set to 1/8. The only difference between the two rows is the top one had the SB800 switched on, and it was switched off for the bottom row... Weird...

D7000-Ringflash-Test-2.jpg
 
Catdaddy said:
Here's what it's giving me... As I say, SB-800 set to manual 1/128 and mounted onto a D7000, AutoFP switched on, Safari set to 1/8. The only difference between the two rows is the top one had the SB800 switched on, and it was switched off for the bottom row... Weird...

D7000-Ringflash-Test-2.jpg
Click to expand...

What you're getting there, with AutoFP switched on (there's no other way to do it) is the tail-sync hack.

By synching it through the SB800 on FP, the ringflash fires as soon as the shutter starts to open (fractionally before actually) as opposed to when the first curtain is fully open, and because of the long duration the flash is still putting out light as the shutter travels down. At higher speeds, it's only uncovering part of the sensor at any given moment, hence the light fades as the shutter travels down, and the higher the speed, the more evident the shading becomes.

The problems with it are that a) power is very substantially reduced, like two stops or so straight off the bat and reducing further by 50% for every stop the shutter speed is increased, b) uneven exposure, c) potentially uneven colour, as there's usually more red in the tail (not sure how evident that is here), d) with hot shoe guns, it only works on full power because the tail is cut off sharply at lower power outputs, e) unlike with normal FP flash, there's no auto exposure control, and f) you need an FP-enabled donor gun to extract the sync trigger from the camera.

Apart from that, it's great ;)
 
Richard, thanks for taking the time to go into detail. After reading your explanation, I remembered reading an article on the strobist blog some time ago regarding the tail-sync hack, and I discounted it at the time for the very reasons you mentioned.
I'd obviously forgotten completely about the hack till you mentioned it again.

I suppose it may have its uses in some situations, but to be honest, I can't think of any where the image quality is intended for commercial use etc. as you pretty much elude to.

Thanks for the reminder though :thumbs:
 
You're welcome Michael :)

Strobists have a fondness for it because, to be blunt, cheapo workaround bodges have an appeal in certain circles ;) :D (He said, looking down his nose LOL)

It could be argued that in Chris' images, the one at 1/800sec might be good enough in some circumstances, but in practise the occasions where that would even be viable given the downsides, let alone acceptable, are few. And there are much better alternatives.
 
HoppyUK said:
It could be argued that in Chris' images, the one at 1/800sec might be good enough in some circumstances, but in practise the occasions where that would even be viable given the downsides, let alone acceptable, are few. And there are much better alternatives.
Click to expand...

Agreed :agree:
 
Thanks for all the help, guys... I can see I'm gonna have to get out there and experiment a tad - I've not really had the chance as yet... Hoping to in the next couple of days though... :thumbs:
 
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