Helpful Hints/D.I.Y.: High Speed Flash Sync 1/8000 sec f/2.8 Mid Day

Bobby Deal · Apr 30, 2010

Some of you may already know this trick. Unfortunately for the Canon crowd I don't think it is possible but for Nikon shooters it is possible to sync the Nikon D300 and a Calumet Travel Lite 750 monolight at 1/8000 sec and then shoot outside at f/2.8 and get a proper exposure at mid day on a bright and sunny day?

Nikon D300
ISO 100 1/8000 second f/2.8 at 10:45ish AM
Calumet Travel Lite 750

Image EXIF

Nikon D300
ISO 100 1/8000 second f/2.8 at 10:58 AM
Calumet Travel Lite 750

Image EXIF

Nikon D300
ISO 100 1/800 second f/4 at 11:42 AM
Calumet Travel Lite 750

Image Exif
© 2010 Bobby Deal

The secret - Your Nikon must have the 250 or 320 FP sync setting in the Flash Sync menu. If it does then this trick will work for you too

Nikon SB 800
Manual 1/124 FP
Sync Cable between SB800 and monolight
Set your shutter speed at what ever you want and it will sync up. Have fun shooting @ f/2.8 in bright sun. In the right conditions you can even use this technique to turn day to night

Doug Kerr · Apr 30, 2010

Hi, Bobby,

Bobby Deal said:
Some of you may already know this trick. Unfortunately for the Canon crowd I don't think it is possible but for Nikon shooters it is possible to sync the Nikon D300 and a Calumet Travel Lite 750 monolight at 1/8000 sec and then shoot outside at f/2.8 and get a proper exposure at mid day on a bright and sunny day?

Interesting.

Can you tell us the principle that makes this possible? Is it an "electronic shutter" mode of sensor operation at 1/8000 sec while the FP shutter itself is run at perhaps 1/320 sec?

Sure nice to be able to do that.

Doug Kerr · Apr 30, 2010

Hi, Bobby,

I'm a little bit surprised by some of the numbers here. I'll refer to your last shot. I'm assuming that the exposure of the wall is primarily by ambient illumination, and that the flash here was principally for "shadow fill" on the models.

Where you are, at that time of day, for ISO 100 and an f/4.0 aperture, we might expect "proper" ambient exposure to come in at about 1/2000 sec, but this shot was at 2 stops less than that.

Best regards,

Doug

Doug Kerr · Apr 30, 2010

Hi, Bobby,

Bobby Deal said:
The secret - Your Nikon must have the 250 or 320 FP sync setting in the Flash Sync menu.

I'm having trouble finding this menu in the D300 manual. Can you help me out here?

Thanks.

Best regards,

Doug

Bobby Deal · Apr 30, 2010

Doug_Kerr said:
Hi, Bobby,

Interesting.

Can you tell us the principle that makes this possible? Is it an "electronic shutter" mode of sensor operation at 1/8000 sec while the FP shutter itself is run at perhaps 1/320 sec?

Sure nice to be able to do that.

Hi Doug, not being an engineer I can't really answer this question, all I know for sure is that it works. Why it works I will have to leave to someone who knows the actual electronics behind the equipment.

Bobby Deal · Apr 30, 2010

Doug_Kerr said:
Hi, Bobby,

I'm having trouble finding this menu in the D300 manual. Can you help me out here?

Thanks.

Best regards,

Doug

Custom Setting Menu

e. Bracketing/Flash > e1. Flash sync speed 320FP(Auto)
once this is set

set your SB-800 to M FP 1/128 and go with a sync cord from speedlight to monolight and you are good to go.

The beauty of this is that it greatly extends the dynamic range of the image had we metered for the wall @ 1/2000 f/4 we would have seen significant underexposure on the models

Doug Kerr · Apr 30, 2010

Hi, Bobby,

Bobby Deal said:
Custom Setting Menu

e. Bracketing/Flash > e1. Flash sync speed 320FP(Auto)
once this is set . . .

Well duh! I was looking at the D3000 manual.

Thanks.

Best regards,

Doug

Bobby Deal · Apr 30, 2010

I have not played with the D3000 not sure if it has the FP mode but any Nikon that does have the FP Mode should be able to do this.

Doug Kerr · Apr 30, 2010

Hi, Bobby,

Bobby Deal said:
I have not played with the D3000 not sure if it has the FP mode but any Nikon that does have the FP Mode should be able to do this.

Are we sure what we are seeing here is not just the normal high speed FP mode of the SB-800 (and the Calumet monolight is not really contributing)?

That would make perfect sense.

Are you familiar with the concept behind the high speed FP mode? If not, let me know, and I'll give you a brief run-down.

With my Canon EOS 40D and a Canon Speedlite 580EX II in the high-speed FP ("high-speed sync") mode, I can do fine at 1/8000 sec.

I think the D3000 does not support high speed FP mode operation.

Best regards,

Doug

Bobby Deal · Apr 30, 2010

No the SB-800 is definitely not contributing to the exposure. It is set to Manual FP 1/128 and pointed straight up with a diffuser cap on the head. The SB-800 is being used as a wired trigger to fire the Travel Lite 750 which is definitely contributing to the exposure. You can see that the Travel light is contributing to the exposure by the angle of shadows in the shots on the gypsy wagon

I don't really know the theory behind the FP mode and really don't use speed lights except when event shooting so this was a total experiment to me. I spend 95% of my photographic life inside the studio so this is all fun and exploration for me if you can share more of the theory behind the technique with me that would be wonderful. There is no doubt though that the Monolight is effectively acting as my keylight. I also was unaware that Canon had the equivalent FP mode for their Speed lights. If they do have the same mode then the Canon shooters should also be able to take advantage of this.

Doug Kerr · Apr 30, 2010

Hi, Bobby,

Bobby Deal said:
No the SB-800 is definitely not contributing to the exposure. It is set to Manual FP 1/128 . . .

I assume you mean that the SB-800 flash is set to manual 1/128 and goes into the FP mode because of the shutter speed set on the camera. As I understand it, there is no setting for "FP mode" on the SB-800 itself.

. . . and pointed straight up with a diffuser cap on the head. The SB-800 is being used as a wired trigger to fire the Travel Lite 750 which is definitely contributing to the exposure. You can see that the Travel light is contributing to the exposure by the angle of shadows in the shots on the gypsy wagon[

Yes - I didn't know which flash units were there so I couldn't interpret the shadows.

So, OK. Then I am still mystified as to what is going on here. But it may come to me.

I also was unaware that Canon had the equivalent FP mode for their Speed lights. If they do have the same mode then the Canon shooters should also be able to take advantage of this.

Yes, but not involving an external flash unit - it only works when the SpeedLite is the source of the flash illumination.

And in any case I can't yet imagine how a dedicated on-camera flash unit, used as a "wired trigger" to electrically fire a non-dedicated external flash, could make that external flash unit use an "FP burst" - unless it has that capability itself. Does the external flash by any chance have an FP mode?.

Thanks for staying with me on this.

Best regards,

Doug

Asher Kelman · Apr 30, 2010

Doug,

I also don't understand what's gong on. Has Calumet engineered their unit to be triggered by the SB-800 and then Calumet fires as if it's a slave SB-800 unit in some super-short flash duration? I'd do the same f 2.8 and strobe exposure using a neutral density filter with the Canon. I believe that's what Frank Doorhof does with his Elinchrom strobes and his Canon DSLR's.

Asher

charlie chipman · Apr 30, 2010

Here is my guess at what is going on and I will experiment later and see if I can make it work with a D200, D700 and various flash units. Perhaps it is specific to the circuitry of the calumet monolight?

From my understanding when in FP mode the SB-800 will produce a very quick burst of low powered flashes as opposed to one high powered flash when in the normal operating mode.

Perhaps it is possible that the flash sync output of the SB-800 is also sending the same burst as a trigger(s), where if you plug in to the camera sync you would not get this burst but only a single trigger. (I will try to hook up my oscilloscope next week to see if I can verify this.)

Now let's say that this is what is going on, mind you I am not familiar with flash circuitry, but if a mono light such as the calumet travel lite is wired in such a way that it does not need to recycle fully before it fires the next flash then it would trigger the flash as a quick burst like the SB-800 does in FP sync mode? Most likely at reduced power?

Perhaps coincidentally the circuitry of the Calumet monolite is the same as an SB-800 and its FP mode only on a larger scale?

However it works it is quite interesting, thank you Bobby for posting this.
I will see if I can make it work with my packs.

Doug Kerr · Apr 30, 2010

Hi, Asher,

Asher Kelman said:
I also don't understand what's gong on. Has Calumet engineered their unit to be triggered by the SB-800 and then Calumet fires as if it's a slave SB-800 unit in some super-short flash duration?

No, super-short is not what's needed here. What is needed is a burst (typically made of a string of very short pulses) that lasts perhaps 1/300 sec overall (while the narrow slit of the FP curtain makes its full traverse of the frame).

Best regards,

Doug

Doug Kerr · Apr 30, 2010

Hi, Charlie,

charlie chipman said:
Here is my guess at what is going on and I will experiment later and see if I can make it work with a D200, D700 and various flash units. Perhaps it is specific to the circuitry of the calumet monolight?

From my understanding when in FP mode the SB-800 will produce a very quick burst of low powered flashes as opposed to one high powered flash when in the normal operating mode.

Actually, a relatively long (maybe 1/250 sec) burst of repeated very short flash pulses.

Perhaps it is possible that the flash sync output of the SB-800 is also sending the same burst as a trigger(s), where if you plug in to the camera sync you would not get this burst but only a single trigger. (I will try to hook up my oscilloscope next week to see if I can verify this.)

Yes, that thought briefly crossed my mind. This would certainly require the external flash to have an unusual behavior - ordinary, one it gets the trigger closure it is commiited for one "poof".

Now let's say that this is what is going on, mind you I am not familiar with flash circuitry, but if a mono light such as the calumet travel lite is wired in such a way that it does not need to recycle fully before it fires the next flash then it would trigger the flash as a quick burst like the SB-800 does in FP sync mode? Most likely at reduced power?

Yes, maybe so. I need to look at the poop sheet for that Calumet and see if it says anything about such a supernatural thing.

But it's a fascinating matter.

Thanks, Charlie, for your thoughts.

Best regards,

Doug

Bobby Deal · Apr 30, 2010

Buried in end of month paper work but I will be back to this later tonight.

FWIW This is not Calumet spscific I believe it can be done with any mono light.

The SB 800 Does have a FP mode or at least reads that the camera is in FP mode and displays FP in the SB800 display

I believe what is happening is actually pretty simple

The camera is set to High Speed Sync. Normally this would only work with the compatible speedlight but by setting the speed light to minimal power and directing it away form the subject so it does not contribute to exposure and then connecting the speedlight then when connecting the sync cable between speed light and monolight you are effectively turning the speedlight into a wired trigger.

The camera does not know the monolight is in the chain, the camera believes the speed light is the only light contributing to the exposure and since we are not in TTL it is relying on us to adjust power settings to achieve proper exposure. The mono light fires in sync with the speedlight because of the cable and effectively becomes the speed light.

The flash duration oif the monolight is longer then the 1/8000 shutter speed thus creating an ovellap and a false high speed sync betyween the camera in High Speed Sync mode and the Monolight.

End result the mono light provides a balancing burst of light during the 1/8000 shutter and extends the dynamic range of the shot.

Again I am not an overly technical kind of guy and don't know all the physics and algorithms behind the high speed sync mode all I really know is that it works and for me that is the crux of the issue. In the end I don't really need to know (though I would like to know) why it works as long as it works

Doug Kerr · Apr 30, 2010

Hi, Bobby,

Thanks for your thoughts, but it doesn't work for me.

Let me discuss the technical issue here. You may know some or all of this, but I'll just do the whole thing.

The typical dSLR FP shutter, for speeds shorter than maybe 1/320 sec, never opens across the entire frame at the same time. Rather, the first curtain starts to move at the beginning of the exposure, opening the frame, and then the second curtain follows close behind, closing the frame. As a result, only a small open "slit" passes across the frame, taking perhaps 1/300 sec to make the whole trip. But, depending on the width of the slit (narrower for higher speed settings), any spot on the sensor is only exposed for the time the open slit takes to pass it, which is the desired exposure time (maybe 1/8000 sec).

Now, the problem with this when flash is involved is that the flash output takes place very quickly (maybe over in 1/1000 sec) and whenever it fires, only a small part of the sensor is exposed (wherever the slit is right then). Thus only part of the scene (typically a narrow horizontal stripe) receives the benefit of the flash exposure.

To get around this, we use the "FP" mode of the flash, often called "high speed sync" or "FP sync", but in fact it is not a special type of synchronization that is involved, so those names are quite misleading. What is different is that the overall burst from the flash is quite long (perhaps 1/300 sec). Thus, it illuminates the whole scene for long enough for the traveling slit to "scan" the whole scene. Thus, all of the frame is effectively exposed.

Now, this is not actually a long continuous burst. Rather, it is a very rapid series of extremely short bursts - acting overall like a quite long burst.

So you see the cause of my mystification here. Unless the monolight can generate such a burst, there is no way that it can provide flash illumination effective for the whole frame with an FP shutter operating at a short exposure time (shorter than perhaps 1/320 sec).

Perhaps with this background in hand, you may recognize some factor, not yet known to me, that will explain what is really going on here.

Best regards,

Doug

Doug Kerr · Apr 30, 2010

Hi, Bobby,

What happens if you just run a sync cord from the sync connector on the D300 to the Calumet monolight?

Best regards,

Doug

Doug Kerr · Apr 30, 2010

I said earlier:

To get around this, we use the "FP" mode of the flash, often called "high speed sync" or "FP sync", but in fact it is not a special type of synchronization that is involved, so those names are quite misleading. What is different is that the overall burst from the flash is quite long (perhaps 1/300 sec).

That was perhaps not as carefully said as it might have been.

Although the central feature of the "FP" mode is the different kind of burst, there is also a special type of sync timing involved.

Normal "X-sync" triggers the flash as soon as the first curtain is fully open. If the shutter speed is fast enough that the second curtain starts to close before the first curtain is fully open, the second curtain will already cover part of the frame when the flash is triggered

With FP operation in effect, the flash is triggered shortly before the first curtain starts to open (so the long flash burst given in that mode will already have begun when the frame first begins to open).

Best regards,

Doug

Doug Kerr · May 1, 2010

By way of demonstration, here are shots taken with a Canon EOS 40D using a Vivitar 285HV flash unit operated on an "X-sync" basis. The flash unit was set for manual operation at 1/16 of maximum output. No special "FP" burst was used (none is in fact available on that flash unit).

Recall that, as seen on the image, the travel of the FP shutter curtains is upward. The edge of the black portion is where the leading edge of the second curtain, starting its travel before the first curtain is completely open, has progressed to when the first curtain is completely open, when the flash is fired.

Here the shutter speed is 1/400 sec:

Here the shutter speed is 1/800 sec:

Here the shutter speed is 1/1600 sec:

The gradient on the edge of the boundary represents the travel of the curtain while the burst "ramps up and down".

Note that the width of the gradient is less for the first shot; the speed of the second curtain is not up to its maximum (governed) value at that point in its travel.

Best regards,

Doug

Bobby Deal · May 1, 2010

Doug_Kerr said:
Hi, Bobby,

Thanks for your thoughts, but it doesn't work for me.

Let me discuss the technical issue here. You may know some or all of this, but I'll just do the whole thing.

The typical dSLR FP shutter, for speeds shorter than maybe 1/320 sec, never opens across the entire frame at the same time. Rather, the first curtain starts to move at the beginning of the exposure, opening the frame, and then the second curtain follows close behind, closing the frame. As a result, only a small open "slit" passes across the frame, taking perhaps 1/300 sec to make the whole trip. But, depending on the width of the slit (narrower for higher speed settings), any spot on the sensor is only exposed for the time the open slit takes to pass it, which is the desired exposure time (maybe 1/8000 sec).

Now, the problem with this when flash is involved is that the flash output takes place very quickly (maybe over in 1/1000 sec) and whenever it fires, only a small part of the sensor is exposed (wherever the slit is right then). Thus only part of the scene (typically a narrow horizontal stripe) receives the benefit of the flash exposure.

To get around this, we use the "FP" mode of the flash, often called "high speed sync" or "FP sync", but in fact it is not a special type of synchronization that is involved, so those names are quite misleading. What is different is that the overall burst from the flash is quite long (perhaps 1/300 sec). Thus, it illuminates the whole scene for long enough for the traveling slit to "scan" the whole scene. Thus, all of the frame is effectively exposed.

Now, this is not actually a long continuous burst. Rather, it is a very rapid series of extremely short bursts - acting overall like a quite long burst.

So you see the cause of my mystification here. Unless the monolight can generate such a burst, there is no way that it can provide flash illumination effective for the whole frame with an FP shutter operating at a short exposure time (shorter than perhaps 1/320 sec).

Perhaps with this background in hand, you may recognize some factor, not yet known to me, that will explain what is really going on here.

Best regards,

Doug

Thanks Doug for that explaination of the FP shutter sync process. I was unaware that this was how it worked but it makes perfect sense.

Now from the Calumet Travel Lite Spec Sheet

Flash Duration (t=0.5, Full Power) 1/650

I am no expert here but as I understand the technical aspects of it T.1 durations are generally 3x the duration of a t.5. So if you round the t.5 flash duration at full power to 1/600 sec That means that it has a t.1 full power flash duration of around 1/200s and thus the burst should indeed be long enough to accommodate the FP shutter process of 1/320.

Bobby Deal · May 1, 2010

Doug_Kerr said:
Hi, Bobby,

What happens if you just run a sync cord from the sync connector on the D300 to the Calumet monolight?

Best regards,

Doug

A very tiny slit of exposure in the lower left quarter of the frame with the remainder black

Which leaves the SB-800 as a vital piece of the puzzle or is it the hot shoe that is the vital piece.
I wanted to run the sync cord from hot shoe mounted sync connector to the calumet to test the idea and I have about 50 of them here in the studio but never use them so of course I can not find one

Bobby Deal · May 1, 2010

Here is the poop sheet for the Calumet 750 http://www.calumetphoto.com/item/CE1325K1/specifications

Doug Kerr · May 1, 2010

Hi, Bobby,

I think you may be on to something.

Bobby Deal said:
Thanks Doug for that explanation of the FP shutter sync process. I was unaware that this was how it worked but it makes perfect sense.

Now from the Calumet Travel Lite Spec Sheet

Flash Duration (t=0.5, Full Power) 1/650

Yes, I noticed that.

I am no expert here but as I understand the technical aspects of it T.1 durations are generally 3x the duration of a t.5.

Probably that is typical. The t 0.5 pulse width is the time between the point where the luminous output has risen to 0.5 of its maximum (that is, its maximum for this output setting) to when it has reached its maximum and then dropped to 0.5 of that.

The t 0.1 time is the time from when the pulse has risen to 0.1 of its maximum until it has peaked and fallen to 0.1 of its maximum.

So if you round the t.5 flash duration at full power to 1/600 sec That means that it has a t.1 full power flash duration of around 1/200s and thus the burst should indeed be long enough to accommodate the FP shutter process of 1/320.

Indeed. Note however that during much of that time the output is considerably less than the maximum. Thus we might expect some "gradient" of illuminance across the frame.

For example, based on your assumed typical ratio of the t 0.5 pulsewidth to the t 0.1 pulsewidth, for 2/3 of the t 0.1 pulsewidth the output would be 1 stop (or more) below the output at the peak.

And maybe careful examination of the images will show something consistent with that.

But, are you in fact using the monolight set to full output (you might have said, but I don't remember)? If not, then the pulse width will be less (very roughly in proportion to the output level you set).

And that could screw up the notion.

In any event, what would be valuable is to do a shot only illuminated by the same flash setup (no daylight ambient), in which case we could more clearly see any gradient of exposure across the frame.

Thanks for staying with this.

Best regards,

Doug

Bobby Deal · May 1, 2010

I will work on some controlled shots tomorrow or Sunday as I find the opportunity.

The outside shots were done at approximately 3/4 power from the monolight

Doug Kerr · May 1, 2010

Hi, Bobby,

Bobby Deal said:
I will work on some controlled shots tomorrow or Sunday as I find the opportunity.

Good. That should be interesting.

The outside shots were done at approximately 3/4 power from the monolight

Well, then maybe your conjecture could check out.

But how would you have done that? The unit seems to only offer output control in 1/2-stop steps.

Best regards,

Doug

Doug Kerr · May 1, 2010

Hi, Bobby,

Bobby Deal said:
A very tiny slit of exposure in the lower left quarter of the frame with the remainder black.

That would perhaps be consistent with the external flash being triggered on an FP sync basis from the PC sync connector. (Triggered just before the first curtain opens.)

Which leaves the SB-800 as a vital piece of the puzzle or is it the hot shoe that is the vital piece.

Seems like it must be something like that.

I wanted to run the sync cord from hot shoe mounted sync connector to the calumet to test the idea and I have about 50 of them here in the studio but never use them so of course I can not find one

Of course!

Best regards,

Doug

charlie chipman · May 1, 2010

I did some experimenting and here are my results.

I used a D700, SB-800, profoto acute2 1200 pack, and a light meter measuring F/8 at the microphone for the first two tests and F/32 for the last.

Which sync port was used made no difference, sync cable plugged into either the D700 or the SB-800 the pictures came out the same. The SB-800 set to FP being attached to the camera is the key to doing this, as well as the power setting of the Acute pack.

All pictures in all series were shot with aperture set to F/8, shutter speeds are on the corresponding pictures.

First batch was normal sync from D700 to acute pack with no SB-800 just for example.

That of course it what we would expect to see.

For this next series I have hooked up the SB-800 in FP mode set to manual 1/128 and turned the head backwards, it is not contributing to the exposure.

The acute pack measuring F/8 at the microphone

Flash duration of the Acute pack is 1/560 sec @ maximum power, 1/3200 sec @ minimum power.
Here it is set very close to minimum power so flash duration is close to 1/3000.

Finally I have the same settings as above only now I have turned acute pack to full power which is 1/560 flash duration.

Again aperture is F/8, the light measurement at the microphone is F/32.

Bart_van_der_Wolf · May 1, 2010

charlie chipman said:
I did some experimenting and here are my results.

I used a D700, SB-800, profoto acute2 1200 pack, and a light meter measuring F/8 at the microphone for the first two tests and F/32 for the last.

Which sync port was used made no difference, sync cable plugged into either the D700 or the SB-800 the pictures came out the same. The SB-800 set to FP being attached to the camera is the key to doing this, as well as the power setting of the Acute pack.

The only explanation I can come up with is that the slower declining tail of the discharge curve is being used for the actual exposure. So the peak output is already gone when the first shutter leaf is starting to clear the sensor plane. That would still produce an exposure gradient as the slit traverses the sensor plane, but perhaps the gradient is not so steep as to notice on a busy background. I do notice the gradient on Charlie's background.

Maybe using a sync cable of adequate length combined with a slightly (too) fast shutter sync introduces just enough delay to miss the discharge peak? Large flash tubes can have relatively long discharge curve tails which could be exploited for that. It would be a less useful feature if one needs to freeze motion, e.g. for jump photography, unless the peak itself is powerfull enough, or the electronics drain the charge for a shorter effective flash curve duration.

Cheers,
Bart

P.S. The new Pocketwizard series of wireless flash sync units (MiniTT1 and FlexTT5) allows to precisely adjust the (pre-)trigger moment of the attached flash unit. On many camera bodies (Canon, and Nikon is being implemented) it allows to add another (or even two) regular shutter speed step(s) before the strobed Hi speed sync kicks in (thus adding more flash reach in broad daylight), called HyperSync. I suppose it could be used to delay sync as well, have yet to try that.

Doug Kerr · May 1, 2010

Hi, Charlie,

Thanks so much for this wonderful test series.

charlie chipman said:
I did some experimenting and here are my results.
. . .

First batch was normal sync from D700 to acute pack with no SB-800 just for example.

That of course it what we would expect to see.

Indeed. You do not mention here the output level of the Acute pack, but my guess (from the narrow gradient on the boundary in the image) is that is was set fairly low (thus a short burst).

And this clearly indicates that the sync here is X-sync (flash triggered just after the first curtain is completely open).

For this next series I have hooked up the SB-800 in FP mode set to manual 1/128 and turned the head backwards, it is not contributing to the exposure.

The acute pack measuring F/8 at the microphone

Flash duration of the Acute pack is 1/560 sec @ maximum power, 1/3200 sec @ minimum power.

Here it is set very close to minimum power so flash duration is close to 1/3000.

Firstly, here, presumably with the shutter speed at 1/250, system operation was not on an FP basis. Even when the FP mode is "ON", the system does not employ it unless the shutter speed is above the X-sync limit (settable on a D300 to 1/250 or 1/320 - haven't looked at the manual for the D700 yet.

Thus the exposure there was "normal".

Now, at the faster shutter speeds, all I can think here is (and I'm with Bart on the second of these):

• The Acute pack is being fired on an FP-sync basis (just before the shutter begins to open)

• The exposure here is from a long tail of the Acute burst.

I think you did not mention here how the Acute pack was being triggered - from the PC connector on D700, or from the PC connector on the SB-800. Based on the overall issue here, I am assuming the latter.

It would not be surprising if, with the system in the FP mode that the SB-800 sync output would be on an FP-sync basis.

But it would not be out of the question that, with the system in the FP mode, the sync output from the D700 (via its PC connector) might be on an FP-sync basis as well. (Recall it is still the camera that determines the proper firing instant for FP flash operation - however it sends that to a dedicated flash.)

All very interesting.

Thanks again for the wonderful test series.

Best regards,

Doug

Helpful Hints/D.I.Y.: High Speed Flash Sync 1/8000 sec f/2.8 Mid Day

New member

Well-known member

Well-known member

Well-known member

New member

New member

Well-known member

New member

Well-known member

New member

Well-known member

OPF Owner/Editor-in-Chief

New member

Well-known member

Well-known member

New member

Well-known member

Well-known member

Well-known member

Well-known member

New member

New member

New member

Well-known member

New member

Well-known member

Well-known member

New member

pro member

Well-known member