Sundry flash durations.

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,820
Was looking at sundry flash units and their speed durations. Surprised to read the Profoto B1X was fairly quick at 1/400 sec. compared to small flash units. Some report the sync might be an issue with some shutter where full X sync might be low at 1/200 sec. (Nikon Z7 II, ahem!).

I've had occasional issues where the camera's sync speed was a bit off and I had to go to a slower shutter speed. Then I was blaming the camera's shutter and never really thought about the flash itself. So I dragged out my low use Nikon SB-900 and put it through the scope to check what it was doing. It was slower and would sync up better than a Godox. Very odd.

Below are all full power pops of my flash units and their duration. Very surprised my old Vivitar 285 was really long and maybe the old film camera flashes (Which the 285 was.) had a longer burn duration) or a different quench circuit asit has some weird cutoff blip at the end of its flash..

Godox-AD-600-TTL-Pro.jpg
Subscribe to see EXIF info for this image (if available)

Godox-TT-685-O.jpg
Subscribe to see EXIF info for this image (if available)


Godox-TT-350-O.jpg
Subscribe to see EXIF info for this image (if available)

Nikon-SB-900.jpg
Subscribe to see EXIF info for this image (if available)

Vivitar-285.jpg
Subscribe to see EXIF info for this image (if available)
 

exakta

Mu-43 Top Veteran
Joined
Jun 2, 2015
Messages
924
Those numbers all look really odd to me since the rule of thumb back in the film days was that strobes had a duration of 1/1000 or even less when in auto mode at close distances. I do remember large studio flashes (Novatrons, etc.) which were slower, closer to 1/500. Were you using HSS?

The Vivitar 285 at only 1/42 looks like a flash bulb! Here's the spec from the 285 manual:

Screen Shot 2021-09-12 at 6.32.01 AM.png
Subscribe to see EXIF info for this image (if available)
 

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,820
Those numbers all look really odd to me since the rule of thumb back in the film days was that strobes had a duration of 1/1000 or even less when in auto mode at close distances. I do remember large studio flashes (Novatrons, etc.) which were slower, closer to 1/500. Were you using HSS?

The Vivitar 285 at only 1/42 looks like a flash bulb! Here's the spec from the 285 manual:

View attachment 907469
I agree. They do indeed look different and why I posted it.

All were in full manual mode and just pressing the button on the flash to fire it. No HSS was on or anything. The Godox specs say the AD 600 runs about 1/220 so I guess the 1/167 might be within their spec tolerance given it tails off quite a bit too. They don't mention the t0.x timing factor either and which they use as that also affects the exposure. Hard to make a useful comparison with the trailing slopes or where they put the peak at. But they all differ from somehow looking at the scope.

Profoto lists the t0.1 and t.05 times which all the players seem to differ on, but their slowest is 1/400 second. Could be they measure higher on the slope (faster speed) than way out to where the flash actually ends instead mid-slope or something, something like a t0.5 or more. Dunno.

Odd too why Profoto added in their specs that the Z7 II has some issues with the assist AF beam whereas the other Nikons don't. I know Nikon lowered their X sync from 1/250 to 1/200 in my switch from the D800E to the Z7 II and am puzzled as to why they changed it slower on newer camera. I got a bad thought they might be doing it intentionally as their SB-900 has a much longer burn (1/191) which might be some sneaky sales pitch for using their gear. I also know - first hand too - that the SB-900 overheats quickly so the longer burn might be cooking the flash and why it goes into a themral shutdown so soon on full pops. One of mine goe hot enough one AA battery blew out and cracked the battery door. Cost me $150 for a plastic battery door from them. I think they lengthen the shot interval or changed the auto-thermal shutdown fuse in the later models to keep them for over-heating.

The Vivitar does look like a flashbulb in its long burn time. Their spec sheet might be for a "fastest speed" marketing claim since that seems to be a stronger sales point. Thinking about their 1/1000 sec. duration burn, that would not cover a camera whose shutter X-sync'ed at say 1/250. I think they error'd on being the fastest maybe for marketing (Maybe using a t0.7 time?), but the tail end does go on much longer.

Some manufacturers show a range of duration speeds. I think Vivitar made two different models of the 285 as one had a higher trigger voltage and might damage some electronic cameras that use a transistorized trigger instead of some contacts in the shutter. Mine is a bit higher than I'd like, but haven't burned up anything yet. I use it on a remote receiver shoe instead of a camera. It does show an odd jagged "clip" at the end of its flash burn that the others don't. Sometimes its more pronounced too.

My Vivitar 285 also has that gold color in the flash head lens or reflector and maybe they warmed it up for film much like Paul Buff did by making some gold colored UV flash tubes for the blue Ektachrome films. ( Link: Paul Buff flashtubes Note one is Uncoated and 5,600K, and the UV coated ones are 5,200K in their specs. ) The UV ones have what looks like a hand-painted gold stripe on the side of that tube. Their White Lightning Ultras used two of those flash tubes. I put one UV tube and a normal in my old heads to warm them up a bit. Least with two tubes there is a backup redundancy as it still fires on one tube, albeit less output.

Interesting comparing all this stuff.
 

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,820
Very odd why these new cameras are having fits with some flash units. Seems Canon R6 owners are also having issues with sync now.

https://www.dpreview.com/forums/post/65475698
Might get down to "Use our flash stuff and not third party." They keep this up and everyone will move to cellphone cameras for ease of operation. :hiding:

Shades of "Why my old Sigma 35mm f/1.4 ART lens doesn't play nice with the Sigma AF calibration dock and the Z7 II FTZ lens adapter." AF tuning works via the Nikon Z7 II menu, but anything I do in the Sigma tuning dock is not recognized by the Z7 II. No answer from Siggy either as to why, but they don't make a hacked Z mount lens yet either.

Even Micheal Tapes said "He is not going to support the new Nikon Z7" in his FocusTune software in a recent note to me (Fyi: He has throat cancer. He put it on his Youtube channel.). Nikon is changing things up a bit.

"Where's my cellphone camera? I need to take some photos without brain engaged." :laugh1:
 

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,820
A possible reason for the flash duration differences might be in how the capacitor was designed.

Wiki: https://en.wikipedia.org/wiki/Photoflash_capacitor

And this from some engineer:
"Camera flash capacitors are constructed to have low resistance, and more importantly, low inductance, so that they can deliver their energy to the flash tube as quickly as possible — which means achieving a fast rise time on the pulse of current. The internal connections are also made more robust in order to avoid localized heating as a result of the high current."

The forty year old Vivitar 285's extended duration time of 1/42 second might be because it has a higher internal resistance capacitor inside it which might throttle out the duration burn longer than some newer flashes with a shorter duration and with more brightness too. It also seems very slow to charge against newer ones: i.e. Electric flow slow going in, and slow going out?

Maybe also the amount and pressure of the xenon gas in the tubes. I never really thought that much amount the X-sync factor of an electronic flash and why it is important in duration and coverage of the sensor's open time. I always blamed the camera speed and not thinking about what the flash may be doing.

Now reading in DPR where the new Canon R6 and in NikonCafe where the new Nikons are having sync issues with some flashes,this might be a new matter. Even a Nikon Z7 II with an older Nikon SB-900 where they seems to have issues in Program mode and with certain apertures. Very odd things happening.
 

exakta

Mu-43 Top Veteran
Joined
Jun 2, 2015
Messages
924
The Vivitar does look like a flashbulb in its long burn time. Their spec sheet might be for a "fastest speed" marketing claim since that seems to be a stronger sales point. Thinking about their 1/1000 sec. duration burn, that would not cover a camera whose shutter X-sync'ed at say 1/250.

You may be misunderstanding how X sync works. The flash is fired at the point the shutter is fully open. The max X synch speed on a focal plane shutter is the highest speed where the entire frame is exposed, as opposed to higher speeds where the shutter is a slit moving across the frame.

For X sync, the flash does not have to stay lit for the full duration that the shutter is open, in fact it usually does not. The idea is to guarantee that all of the light is caught, none is wasted.

A quick test to see if the 285 is truly so far below the 1/1000 spec...set up the camera on a tripod in a dark room, set the shutter for 1 second, stand in front of the camera, start the self timer and start jumping up and down as fast as you can :roflmao: or swing you arms around. If the duration is really only 1/42, it won't stop the motion, but if it's 1/1000 it will.

EDIT: What were you actually measuring on the scope, the voltage across the capacitors?
 
Last edited:

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,820
You may be misunderstanding how X sync works. The flash is fired at the [point the shutter is fully open. The max X synch speed on a focal plane shutter is the highest speed where the entire frame is exposed, as opposed to higher speeds where the shutter is a slit moving across the frame.

For X sync, the flash does not have to stay lit for the full duration that the shutter is open, in fact it usually does not. The idea is to guarantee that all of the light is caught, none is wasted.
True, but that thin slit at 1/1000 second shutter setting is traveling at a slower X-sync speed of 1/250. A flash pop at 1/1000 will not cover the 1/250 scan speed as some is covered by the blades. Same as raising the shutter speed to 1/500 (even thinner slit than 1/250 yet blades traveling at same velocity) and you aren't getting the flash duration and its cut off.

Electronic does have a tail to it which makes the effective exposure different, i.e. a t0.1 gives more overall exposure than say a t0.5 burn - but then it's up to the user to determine if they see it or not as it fades. I can see the brightness curve fade with the Sekonic L-858 meter's duration display. Old flashbulbs go way beyond where Sekonic's burn duration display gets cut off.

Aside, I believe Godox is playing with their firmware updates to make a fast pop a bit slower by introducing a sort of HSS to extend the flash duration. Maybe some timing where the flash is located when the shutter fires and is opening too - on average.
 
Last edited:

PakkyT

Mu-43 Hall of Famer
Joined
Jun 20, 2015
Messages
4,587
Location
Massachusetts, USA
For X sync, the flash does not have to stay lit for the full duration that the shutter is open, in fact it usually does not. The idea is to guarantee that all of the light is caught, none is wasted.
Minor correction to that last line. I think you meant, the idea is to guarantee that the entire sensor is exposed to the flash firing. Some may be wasted depending on your aperture as this can be set smaller and let in less light but the full sensor is exposed to the flash regardless of the size of the aperture.

that thin slit at 1/1000 second shutter setting is traveling at a slower X-sync speed of 1/250. A flash pop at 1/1000 will not cover the 1/250 scan speed as some is covered by the blades.

Why would you be setting the shutter to 1/1000? A flash pop of only 1/1000 of a second will cover the entire sensor if that camera body has a flash sync speed of 250 and your shutter is set for 1/250 (or slower).
 

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,820
....

Why would you be setting the shutter to 1/1000? A flash pop of only 1/1000 of a second will cover the entire sensor if that camera body has a flash sync speed of 250 and your shutter is set for 1/250 (or slower).
That is correct. I'm not shooting above sync speed (Okay, maybe with flash bulbs, but that's different and a different sync method with digital too.).

Mine was just an example why a 1/1000 shutter blanks out as it doesn't expose the full frame if the sync was set at 1/250 with electronic flash. Putting your camera at 1/1000 sec is out of the range of a flash that burns for 1/1000 second. The two blades of a 1/1000 second speed shutter are only covering 3/4 of the sensor at that 1/250 sync speed, hence the flash only exposes the one quarter of the frame that's uncovered (e.g. Speed is above the sync speed.).

Now if an electronic flash were to have a duration burn of 1 or 2 seconds instead of 1/1000 second, it would be like a small sun - or like daylight - and no need to worry about sync speeds faster than one second getting cut off. Problem is the electronic flash duration and what duration the shutter is actually uncovered at given the blade's velocity - and that blade velocity is a constant regardless of the shutter speed set.

Given the issues people are having with the new Nikon Z's and the Canon R6 and flash, I believe a lot of it is the duration timing of the old flashes. Just a few milliseconds different and it might be off sync.

the new hot shoes have a Clock, Data, Handshake, the center Flash pin, maybe a fifth ?? pin too, and some flash timing issues are popping up (No pun intended.) in new gear. Olympus quit making their flash extension cable when they took off the center pin in their small FL-LM3 flash that came with the Pen-F and E-M1 II which surprised me. Very odd that sync pin was removed, but they must be triggering that flash via other data pins in their shoes now. Most likely they are digitally controlled now and not by some mechanical switch on the shutter.
 
Last edited:

PakkyT

Mu-43 Hall of Famer
Joined
Jun 20, 2015
Messages
4,587
Location
Massachusetts, USA
they took off the center pin in their small FL-LM3 flash that came with the Pen-F and E-M1 II which surprised me. Very odd that sync pin was removed, but they must be triggering that flash via other data pins in their shoes now. Most likely they are digitally controlled now and not by some mechanical switch on the shutter.
Keeping in mind that the FL-LM3 is not a traditional external hotshoe flash and required connection to an Olympus camera for power. It is basically a built in flash in an external body where all controls for the flash are also in the Olympus body. You can not pick setting in the flash and then fire it so no need for a trigger pin as it isn't used that way.
 

exakta

Mu-43 Top Veteran
Joined
Jun 2, 2015
Messages
924
Minor correction to that last line. I think you meant, the idea is to guarantee that the entire sensor is exposed to the flash firing. Some may be wasted depending on your aperture as this can be set smaller and let in less light but the full sensor is exposed to the flash regardless of the size of the aperture.

If the max X sync for the shutter is 1/n, then any flash burst of 1/n seconds or less is caught in it's entirety. It doesn't matter whether it's a leaf shutter or focal plane shutter. In both cases, the entire sensor is exposed.

I'm still curious what the o-scope traces represent...what was being measured?
 

PakkyT

Mu-43 Hall of Famer
Joined
Jun 20, 2015
Messages
4,587
Location
Massachusetts, USA
If the max X sync for the shutter is 1/n, then any flash burst of 1/n seconds or less is caught in it's entirety. It doesn't matter whether it's a leaf shutter or focal plane shutter. In both cases, the entire sensor is exposed.
Yes, sorry. Rereading your post I see that we said the same thing. When I first responded my brain read that you wrote that the shutter is not usually fully open, which is me read gooder problem. ;)
 

Mack

Mu-43 All-Pro
Joined
Jan 14, 2018
Messages
1,820
....

I'm still curious what the o-scope traces represent...what was being measured?
Traces are the actual (maximum) burn times of the sundry flashes I played with as mentioned above.

The Vivitar 285 is the odd one taking 0.023 seconds (1/42) which is almost like an old flash bulb that takes 0.030-0.040 seconds (excluding some FP-26 bulbs that run out to 0.060-0.70 seconds. Scope time-per-division is shown at top after "Siglent" logo and "Stop." The "Delay" is just the blue diamond on left where it held off the rise pulse of the flash to around the first division.

What the manufactures call their t0.x times is an issue. If they say they use a t0.9 then their reported speeds would be much faster and they are nearer the peak. At a t0.1 they are at the bottom and a longer burn time which might go against their marketing as "We all want it faster so we'll use a t0.5 or t0.? time!" (ahem!).

Scope is showing the entire burn duration - may as well call it a t0.0 time. Sekonic's L-858 HSS meter doesn't allow for a t0.0 setting and lowest is a t0.1 to a t0.9 (fastest) when on the burn's duration curve screen. Most all electronic flashes will end their burn time on the Sekonic meter's display, while an old glass flash bulb will run off the right side of the x-axis time line by burning a lot longer and it may show "Overexposure" too with a bulb.

Also, I was watching the Godox TT-385-O on the E-M1 II and if I just switch the flash sync ON (Where the lightning bolt is displayed for HSS.), the curve flattens out and runs more horizontal at the peak than the above which taper down as they burn out on the full-power pops. Didn't change the Oly speed from 1/200 either, but just throwing the HSS switch to ON changes the exposure a bit which seemed odd. At higher shutter speeds with the L-858 meter's scope, the Y-axis output may drop doing so in HSS as the burn duration is extended if the camera tells the flash it's using a faster shutter speed. Always a trade-off.

Below is the burn time of the Godox TT-685-O and the old Vivitar 285 that shows how the burn tapers down and longer than the 685 that cuts if off abruptly. It's out of focus just shooting at a cabinet, but you get the idea.

Godox-and-Vivitar-Duration-Comparison.jpg
Subscribe to see EXIF info for this image (if available)
 
Last edited:

Latest threads

Links on this page may be to our affiliates. Sales through affiliate links may benefit this site.
Mu-43 is a fan site and not associated with Olympus, Panasonic, or other manufacturers mentioned on this site.
Forum post reactions by Twemoji: https://github.com/twitter/twemoji
Forum GIFs powered by GIPHY: https://giphy.com/
Copyright © Amin Forums, LLC
Top Bottom