Studio Strobe Sync Speed considerations

[phil-t]

This may be a bit silly, but I was following a conversation where someone was getting black bars at the top of their images at the max sync speed of their camera (1/250th) using Einsteins (IGBT) and Pocket Wizards. (The black bars disappear at 1/200th)

Their other camera (same manufacturer, different model) that also has 1/250th max sync worked fine with the exact same trigger/lights.

It was put forward by a few people that strobes can't be used above 1/125th as a 'reason' for the black bars and suggested he lower his shutter speed.

I'm quite new to studio photography, but I've got some DLites that people class as painfully slow (reading around the web), but I use them fine at 1/250th using cheap Pixel Soldiers and optical slave triggering (Or my memory is playing tricks on me)..

I know that slow strobes (like my Dlites that have a t0.1 of 1/266th so I am told) could have a longer flash duration then the shutter, and thus effectively you are wasting light , but I don't see how black bars would be created..

Since it might be something I just don't know about, what considerations are there with modern studio strobes and sync?

 

[Garry Edwards]

The flash used is pretty much irrelevant to this, it's all about two separate factors, the camera shutter and the means of triggering the flash.

Shutter: Some shutters move faster than others, and some have to move a greater distance than others. For example, a pro Nikon camera such as the D700/D800/D3 has an extremely fast shutter, and because of this a faster shutter speed can theoretically be used than with a slower moving shutter. The D300/D300S also has a fast shutter, and because it's a cropped frame camera the shutter is also physically smaller, so again it will synch at a higher shutter speed than some other cameras.

I don't know much about Canon cameras, but I do know that the 5D Mk3 has a much faster shutter than the 5D Mk2.

Then there's the triggering method. A direct connection (synch cord) between the camera and the flash has zero delay (OK, not strictly true but as electricity moves at c, it is pretty much instantaneous). Some high end triggers have an inbuilt (or adjustable) timing correction that allows the shutter to operate correctly at a higher speed than others. Cheap triggers tend to have in inherent delay that has the opposite effect. I've tested really cheap triggers that won't allow a shutter speed faster than 1/30th.

There are of course some triggers that, because of their design, can be used at any shutter speed.

For studio use, shutters speed isn't normally relevant so, in answer to beginner questions, most of us advise them to set the shutter to 1/125th - it may or may not be the fastest speed that can be used with a particular camera, but it's a safe speed.

 

[snoop69]

Not sure if this is relevant but I was was advised that if I needed a faster shutter which caused banding, shoot wide & crop out the banding

 

[phil-t]

Thanks Gary!

If we delve a little deeper, are there some triggering issues that even with a cable, some strobes may struggle to achieve reliable sync (over using a normal hotshoe flash)

i.e. are some strobes known to have slow firing electronics? or do they take so long to reach any appreciable output that black bars can appear? i.e. limiting the effective max sync speed themselves?

I've googled many forum postings where I see things like my older DLites (2008/2009 models) where people swear Elinchrom say that 1/160th is the max sync speed achievable and they can't get even 1/160th reliably with a sync cable, but others come along and say that they've had no issues at 1/250th.. And my own experience is 1/250th is fine, but I tend to just use 1/160 & 1/200th just as I didn't see the point in pushing it (I might even go lower now you've mentioned it!)

 

[Garry Edwards]

There could possibly be issues with some flashes, due to poor components or poor design, but I would be very surprised if they applied to any reputable make.

There is also a potential problem with wired connection. Many years ago, PC connections were formed from solid metal and they just worked. Today, they are split connectors and contact can be poor or intermittent. Add in the factor that modern flashes have to have very low triggering voltages, so that they don't damage modern woosie cameras, and a combination of low voltage (low pressure) and poor contact can create delays, especially intermittently.

Not sure if this is relevant but I was was advised that if I needed a faster shutter which caused banding, shoot wide & crop out the banding

Yes, this is a valid technique, but it has a cost in terms of image quality.

 

[phil-t]

There could possibly be issues with some flashes, due to poor components or poor design, but I would be very surprised if they applied to any reputable make.

There is also a potential problem with wired connection. Many years ago, PC connections were formed from solid metal and they just worked. Today, they are split connectors and contact can be poor or intermittent. Add in the factor that modern flashes have to have very low triggering voltages, so that they don't damage modern woosie cameras, and a combination of low voltage (low pressure) and poor contact can create delays, especially intermittently.
Yes, this is a valid technique, but it has a cost in terms of image quality.

Thanks again Gary, I loved this bit

they don't damage modern woosie cameras

I think that should be on the marketing blurb on the back of the box of every Strobe light..

 

[Garry Edwards]

Thanks again Gary, I loved this bit


I think that should be on the marketing blurb on the back of the box of every Strobe light..

From memory, the problem was created by a certain camera maker in the 90's who created hotshoe electronics for their cameras that couldn't cope with with trigger voltages of greater than around 5.5v. This wasn't a problem for them because their own hotshoe flashguns only used that voltage, but it did create problems for those of their customers who wanted to use competitive makes of flashguns, with much higher trigger voltages, and for a long time virtually forced their customers to either buy their own make of flashgun or fry their cameras

AFAIK there was no problem when connecting either flashguns or studio flashes via the PC connector, but the stuff of urban myths and internet misinformation soon convinced people that ALL cameras of ALL makes could only be used safely at very low trigger voltages, so today, all flashguns, all studio flashes and all radio triggers have very low trigger voltages.

Did I ever tell you why it is that I'm not the world's greatest fan of Canon cameras?

 

[HoppyUK]

Elinchrom D-Lites are not slow, and there are certainly slower flash heads. From your tests it's clear that the problem lies either with the camera or trigger.

The max x-sync speed is always marginal, right on the limit, and some cameras push their luck a bit more than others so may show banding with anything less than an instant trigger signal.

PW's are usually pretty quick, so maybe fresh batteries might pep them up a bit. Or try it with a sync cable as Garry suggested. If that fixes it, it's the trigger; if it doesn't, it's the camera. Keep the flash power setting the same as reducing power makes the flash duation longer and that can make a fractional difference.

 

[paul williams]

The relationship between camera/shutter/trigger is quite a complex issue which I looked at recently. A friend wanted to know what ‘should’ be the maximum achievable sync speed with Multiblitz radio triggers using a combination of (the no longer made) standalone receivers and for heads with the inbuilt receivers. Within the manuals for most of these, the specifications would suggest a 1/250th for a focal plain shutter, but in practice this wasn’t the case. None of my three differing triggers (two still in production) could achieve this (1/250th) with my Canon 40D and the results were worse with the inbuilt receivers in the heads than with standalone receivers. Overall a 1/180th being the best result across all combinations, though surprisingly it was the latest hi-spec (well feature packed) trigger to inbuilt receiver that pulled the maximum sync speed down, the best result being the previous a less hi-tech (but actually more costly) trigger to a standalone receiver.

So camera or trigger system?

Substituting a camera with an in-lens leaf shutter (shooting against a white wall looking for any issues) a sync speed of 1/400th was easily achieved across all combinations with 1/500th for the previous worst Canon/trigger combination. None of which really bothers me per se, as I tend to shoot at 1/125th with my DSLR as a default which is why I never found this to be an issue in the past.

As for flash durations, IMO t.1 times are probably even less relevant than t.5 times! If as I understand it the t.1 time is when the flash ‘output’ has dropped to just 10%, then I’d suspect that at this point the output is having no impact on the image at all :shrug: so what we really need is t.3 times

Paul

 

[phil-t]

Elinchrom D-Lites are not slow, and there are certainly slower flash heads. From your tests it's clear that the problem lies either with the camera or trigger.

The max x-sync speed is always marginal, right on the limit, and some cameras push their luck a bit more than others so may show banding with anything less than an instant trigger signal.

PW's are usually pretty quick, so maybe fresh batteries might pep them up a bit. Or try it with a sync cable as Garry suggested. If that fixes it, it's the trigger; if it doesn't, it's the camera. Keep the flash power setting the same as reducing power makes the flash duation longer and that can make a fractional difference.

Thanks,

I'll pass the info on!

 

[phil-t]

The relationship between camera/shutter/trigger is quite a complex issue which I looked at recently. A friend wanted to know what ‘should’ be the maximum achievable sync speed with Multiblitz radio triggers using a combination of (the no longer made) standalone receivers and for heads with the inbuilt receivers. Within the manuals for most of these, the specifications would suggest a 1/250th for a focal plain shutter, but in practice this wasn’t the case. None of my three differing triggers (two still in production) could achieve this (1/250th) with my Canon 40D and the results were worse with the inbuilt receivers in the heads than with standalone receivers. Overall a 1/180th being the best result across all combinations, though surprisingly it was the latest hi-spec (well feature packed) trigger to inbuilt receiver that pulled the maximum sync speed down, the best result being the previous a less hi-tech (but actually more costly) trigger to a standalone receiver.

So camera or trigger system?

Substituting a camera with an in-lens leaf shutter (shooting against a white wall looking for any issues) a sync speed of 1/400th was easily achieved across all combinations with 1/500th for the previous worst Canon/trigger combination. None of which really bothers me per se, as I tend to shoot at 1/125th with my DSLR as a default which is why I never found this to be an issue in the past.

As for flash durations, IMO t.1 times are probably even less relevant than t.5 times! If as I understand it the t.1 time is when the flash ‘output’ has dropped to just 10%, then I’d suspect that at this point the output is having no impact on the image at all :shrug: so what we really need is t.3 times

Paul

Thanks Paul!

I've seen so much variance in camera/trigger sync reliability being shown around the internet, I can see why 1/125th is actually still a good rule of thumb starting point!

 

[flashted]

most modern studio flash units i see in my workshop will fire with very poor camera contacts and conections. 30 years ago you needed good sync leads for it all to work 100%. Things have improved and now the latest bowens flash will fire with 5000 ohms across the jack socket, thats about 20 miles of sync lead, Profoto is even better at 22,000 ohms. i have noticed that some radio triggers i have tested need a max sync speed of 1/160 to work well, the cheaper ebay unit dont always have a on off switch so it all has to turn on and fire very quickly. The main problems i see with triggering is not the gear but the tog asking too much from the camera and not knowing how they work. David