P-TTL on AF540 GZII - Can you disable preflash?

petrakka · 03-02-2016, 09:44 AM

Hey all, question about the TTL on the AF540 GZII - need to disable the preflash, is this possible?

A little more info - I use a 645D. I shoot a lot of direct (on camera) flash, sometimes coupled with a Profoto (Acute) light or two (in which case I usually just set them on optical slave). I do this in portrait/fashion type work. The pre-flash on the P-TTL mode is killing me. I bought this flash because I had been using a Nikon SB800 on manual mode, but wanted to make things a little faster and easier by getting TTL coupled flash for my 645D. The preflash is killing me in two ways - it causes a shutter actuation delay that, while slight, means something in the way I shoot - I can miss what I want. The second way it's killing me is that I can't fire studio lights via optical slave because the preflash prematurely triggers the light.

I know the workarounds, I have pocket wizards to fire the profotos, but I use the on camera flash or natural light the most. I got the AF540 GZII to make shooting easier and more seamless as I move around a shoot (so I am not calculating flash ratios as I switch lenses and move my distance from subject etc), not because I needed another flash. I called the Pentax service in NC or wherever and chatted with a very nice guy who was as confused as I was and ultimately offered no help. He said he would ask around the shop and email the next day with a definitive answer. Never happened.

Is there any way to get ttl functionality out of this flash without that damned preflash? If so, what terrible design. If everyone else can do it why can't Pentax?

Scintilla · 03-02-2016, 09:58 AM

Originally posted by petrakka

Is there any way to get ttl functionality out of this flash without that damned preflash? If so, what terrible design. If everyone else can do it why can't Pentax?

I thought that all digital-era TTL flash schemes required a preflash, not just Pentax's?

The non-mark-II versions of the 360 and 540 flashes have auto thyristor mode, which I don't believe uses a preflash. It does, however, require you to set the ISO and aperture yourself on the flash.

enoeske · 03-02-2016, 10:19 AM

Originally posted by petrakka

portrait/fashion work

In automatic mode? Dude, you have a 645D, a studio, studio lights and pocket wizards! Why on earth are you using a P-TTL flash in that setup at all? What were you hoping to make easier or speed up by using it?

pathdoc · 03-02-2016, 11:06 AM

The only Pentax digital camera with true TTL flash capability that I know of was the original *ist-D.

CarlJF · 03-02-2016, 11:07 AM - **1 Like**

The P in P-TTL stands for "preflash". So, by definition, there's always a preflash in P-TTL. And it will be the same situation with Canon or Nikon. They're all based on a preflash light measurement... This is how modern flashes work, for all manufacturers, and also one of the reasons many people still prefer to use their flashes in manual mode instead of TTL.

If you don't want a preflash, you should use the flash in manual mode. There's no way around it.

Kameraten · 03-02-2016, 11:09 AM

I would go for manual mode. I assume the 645D behaves like other Pentaxes so when you set it to M you can set the AF540 to M too, and then you can regulate it's output to whatever fraction is needed to trigger your slaves. Then there will be no pre-flash.
With the camera in M you might want also to set the flash sync on-camera to second curtain. That way you will be able to set shutter and aperture to what the ambient light suggests just by pressing the green button. And you might want to modify the way the green button works with M so that it for example works like aperture priority. I think you'll find that option in the menus.

CarlJF · 03-02-2016, 11:30 AM

Why are you mixing TTL and manual studio flashes ? It doesn't make much sense to me. How do you expect the camera to control the power output of the studio flashes ? Which is the point of using TTL flashes... You should use all your flashes in manual or TTL, but not mix fladhes working in different modes...

petrakka · 03-02-2016, 11:53 AM

Originally posted by enoeske

In automatic mode? Dude, you have a 645D, a studio, studio lights and pocket wizards! Why on earth are you using a P-TTL flash in that setup at all? What were you hoping to make easier or speed up by using it?

I don't have a studio, I shoot all location work. I don't off camera strobe for the most part. I usually prefer natural light, and my second preference is hard, bare on camera flash. I have the profotos for when client needs demand it, but in general the more gear on a shoot (including lights) the less happy I am. When I am shooting a moving subject, or we have to do multiple set ups, moving from location to location with TTL I can set it how I want and get pretty consistent look from space to space. A lot of portrait work I like is sort of 'in-between' moments, which the pre-flash can cause me to miss. On editorial jobs my time is often quite limited. It is just a preference thing. This is just a question I asked about how to get something to work, not about justifying the way I like to work.

---------- Post added 03-02-16 at 01:06 PM ----------

Originally posted by CarlJF

Why are you mixing TTL and manual studio flashes ? It doesn't make much sense to me. How do you expect the camera to control the power output of the studio flashes ? Which is the point of using TTL flashes... You should use all your flashes in manual or TTL, but not mix fladhes working in different modes...

It doesn't need to make sense to you, but if you want more info, I have an assistant to control the output of the monoheads. I use the on camera flash TTL to control how much light I want from on camera, within reason. I use the full scope of the +/- exposure compensation of the TTL and when using this method on Nikon or Sony it has worked fine, but for other reasons I prefer to use my Pentax whenever possible for photographing people. I know how it all works, but you work for long enough and you find how you prefer to work and what works best for you, even if it's not the way most people may prefer to work.

I just was trying to figure out if there was a way to kill the preflash.

enoeske · 03-02-2016, 12:07 PM

Originally posted by petrakka

I don't have a studio, I shoot all location work. I don't off camera strobe for the most part. I usually prefer natural light, and my second preference is hard, bare on camera flash. I have the profotos for when client needs demand it, but in general the more gear on a shoot (including lights) the less happy I am. When I am shooting a moving subject, or we have to do multiple set ups, moving from location to location with TTL I can set it how I want and get pretty consistent look from space to space. A lot of portrait work I like is sort of 'in-between' moments, which the pre-flash can cause me to miss. On editorial jobs my time is often quite limited. It is just a preference thing. This is just a question I asked about how to get something to work, not about justifying the way I like to work.

Well, there is no way to disable the P-TTL preflash. Neither is there a way to disable the preflash on Canon's i-TTL or Nikons flashes. You can either use manual flash which does not use a preflash, or get used to the preflash. As CarlJF said, though, I wouldn't mix P-TTL and manual strobes. Its just asking for trouble.

petrakka · 03-02-2016, 12:08 PM

Originally posted by CarlJF

The P in P-TTL stands for "preflash". So, by definition, there's always a preflash in P-TTL. And it will be the same situation with Canon or Nikon. They're all based on a preflash light measurement... This is how modern flashes work, for all manufacturers, and also one of the reasons many people still prefer to use their flashes in manual mode instead of TTL.

If you don't want a preflash, you should use the flash in manual mode. There's no way around it.

Thanks. Interestingly I have not had this problem with the SB-800 on a Nikon or the Nissin i40 on my Sony. Maybe it's that the Pentax preflash is much slower and I didn't notice it on the other cameras, not sure. But okay, so I am stuck with this. Good to know.

---------- Post added 03-02-16 at 01:10 PM ----------

Originally posted by Kameraten

I would go for manual mode. I assume the 645D behaves like other Pentaxes so when you set it to M you can set the AF540 to M too, and then you can regulate it's output to whatever fraction is needed to trigger your slaves. Then there will be no pre-flash.
With the camera in M you might want also to set the flash sync on-camera to second curtain. That way you will be able to set shutter and aperture to what the ambient light suggests just by pressing the green button. And you might want to modify the way the green button works with M so that it for example works like aperture priority. I think you'll find that option in the menus.

Yea, this is what I have been doing, and it is fine. It just can kill the vibe/slow down the shoot some, which is why I want the TTL with no preflash. Basically the more shooting and less fiddling with other controls the happier I am.

---------- Post added 03-02-16 at 01:15 PM ----------

Originally posted by enoeske

Well, there is no way to disable the P-TTL preflash. Neither is there a way to disable the preflash on Canon's i-TTL or Nikons flashes. You can either use manual flash which does not use a preflash, or get used to the preflash. As CarlJF said, though, I wouldn't mix P-TTL and manual strobes. Its just asking for trouble.

I've been fine doing this with other systems for awhile, it hasn't caused me trouble, but alright? I didn't ask for advice on how to shoot, which, if I did then cool, but I just asked if preflash could be disabled.

CarlJF · 03-02-2016, 12:39 PM

Originally posted by petrakka

Thanks. Interestingly I have not had this problem with the SB-800 on a Nikon or the Nissin i40 on my Sony. Maybe it's that the Pentax preflash is much slower and I didn't notice it on the other cameras, not sure. But okay, so I am stuck with this. Good to know.

Are you sure you were not using the SB-800 in manual mode ? As far as I know, people using Canon or Nikon have the exaxt same issue.

The workaround should be the same: using radio trigger or sync cable with the manual flashes. With the radio triggers, you can use a p-ttl cable as a kind of "hot shoe splitter", putting the radio trigger on one end and the ttl flash on the other. Obviously, using a flash bracket would be quite useful to support either the flash or trigger. I haven't tried it, but this should work. I don't know if the 645 has a sync port, but if so, it could also probably be used to trigger the remote flashes directly or with the radio trigger, by pluging it on the sync port instead of the hotshoe....

mcgregni · 03-02-2016, 12:46 PM - **1 Like**

As said by others, if you set a dedicated system flash to its 'TTL' mode, then it must use a pre-flash .... same for all makes, and there would be no technical purpose to disabling the pre-flash when in the TTL mode, because clearly then the TTL mode could not function.

The real issue here is the method you are using to trigger your studio lights, which seems to be optical triggering from the on-camera flash. Unless your off-camera lights have a delay function that can be programmed to delay the flash until the exposure, ignoring the pre-flash, then I don't see how you can avoid your problem. A number of 'speedlight' type flashes, including the Pentax models, have 'Slave Modes' (S1 / S2) which allow the flash to be set to ignore the pre-flash from a dedicated controller flash .... clearly this is not the case for your manual studio lights.

If you cannot programme a delay into your slave flashes, then if you want to use a P-TTL flash on the camera in combination with manual slaves, I think you will need to use a radio trigger system, with the P-TTL flash on top of the trigger. I do this with my Pentax flashes and a Cactus V6 ..... this unit has a 'TTL Pass-through' mode allowing the Pentax flash on top of the V6 to behave exactly as if it is mounted directly to the camera. The pre-flash still occurs, but it comes before the triggering of the slave from the V6, which of course corresponds to the actual exposure and main flash from the Pentax, so all flashes sync without any delay.

petrakka · 03-02-2016, 01:00 PM

Originally posted by CarlJF

Are you sure you were not using the SB-800 in manual mode ? As far as I know, people using Canon or Nikon have the exaxt same issue.

The workaround should be the same: using radio trigger or sync cable with the manual flashes. With the radio triggers, you can use a p-ttl cable as a kind of "hot shoe splitter", putting the radio trigger on one end and the ttl flash on the other. Obviously, using a flash bracket would be quite useful to support either the flash or trigger. I haven't tried it, but this should work. I don't know if the 645 has a sync port, but if so, it could also probably be used to trigger the remote flashes directly or with the radio trigger, by pluging it on the sync port instead of the hotshoe....

So, this workaround - yea, that's what I was thinking, but I don't really want to go there. Might have to, we'll see.

This thread might make it seem like I'm pretty clueless about the new technology speedlights, and basically, I am.

I have used pocket wizards, studio strobes and Vivitar 285's up until a few years ago, so for me it was always all manual and all numbers, and usually all off camera. But I picked up an SB800 by chance a few years back and started using the TTL mode and really took playing with on camera flash, and I really took to it - but I only just started trying to do this with the Pentax in the past year, and just resorting to using the SB-800 in Manual mode on my Pentax. I figured TTL would work as smoothly on the Pentax as the Nikon but, well, nope.

If they all do the preflash, then I am stumped. I have definitely used my SB800 a ton in TTL getting the results I wanted to. Maybe the preflash on it is just imperceptible compared to the Pentax. The main thing I don't like the preflash for is more the delay it causes then the studio light situation. If I used the SB800 with studio lights I guess it must have been in manual. I just have never noticed a preflash on the SB800 in ttl mode. But I rarely mix them because as I stated, I usually prefer just the on camera flash, and that is second to the natural light I most often use. The last time I actually mixed on camera flash with the profotos (besides with the Pentax and the SB800 in manual mode on it, which is what I have mostly done up until I got this 540) was probably almost a year ago. I've only used the profotos a few times in the past year though. I've just had a series of shoots come up in the past few weeks where I needed to mix the two, and it was fine I just went manual mode like I am used to, but wondered if I could work with it in exactly the way I had envisioned - which appears not to be the case.

---------- Post added 03-02-16 at 02:22 PM ----------

Ok, you guys had me thinking I was going nuts so I just got out my flashes for everything - Sony, Nikon and Pentax and tried it all.
I think I can see the preflash from the Nikon and the Sony in TTL, but it is basically imperceptible. It's quite fast.

On the Pentax, it is quite slow, but I also have a strangely sticky mirror on my 645D - sticky enough to even when you shoot at 1/125 you hear distinctly the mirror opening, then closing - I am thinking that it is maybe the sticky mirror that the preflash is syncing to and making it seem so separate and noticeable. The strange thing though - the exposures are still good, it's not like I am getting the ambient light of a slow exposure. I'm not sure what's going on.

CarlJF · 03-02-2016, 01:31 PM - **1 Like**

Were you using the SB-800 on an film body or a digital one ? With film, there's no preflash... I'm asking because doing a google search shows up a lot of people having the same delay problem with the Nikon system...

Have you checked the flash is set on first curtain sync ? Maybe it's set on second curtain sync, making the delay even more obvious...

petrakka · 03-02-2016, 01:41 PM

Originally posted by CarlJF

Were you using the SB-800 on an film body or a digital one ? With film, there's no preflash... I'm asking because doing a google search shows up a lot of people having the same delay problem with the Nikon system...

Have you checked the flash is set on first curtain sync ? Maybe it's set on second curtain sync, making the delay even more obvious...

SB 800 on a D-800 (digital) - and I just tried it out and it's still seamless. (Haven't gotten that d800 for awhile!). But yea, I can't answer why I felt like my Nikon set up always worked with my Acutes, but I've never had an issue with getting stuff to look how I want. All I can think is that, when I brought in the Acutes I must have been in manual mode despite my thinking that I wasn't. That or I have super powers, but I'm pretty sure I don't.

Re: the curtain, I double checked it, but yea it's definitely on first curtain sync - I really think it might have to do with the mirror on my 645D. Maybe I'll see if there's a shop that carries a K5 or something around here that I can try my flash on and see if it works more quickly on that.

Things were so much simpler when I could just use my Contax G2 and Hasselblad and it all just did the few things it was supposed to do. Sigh. This is even making me long for the days of sync cords and light meters.

03-02-2016, 09:44 AM	#1
petrakka Forum Member Join Date: Feb 2016 Location: Chicago Posts: 91	P-TTL on AF540 GZII - Can you disable preflash? Hey all, question about the TTL on the AF540 GZII - need to disable the preflash, is this possible? A little more info - I use a 645D. I shoot a lot of direct (on camera) flash, sometimes coupled with a Profoto (Acute) light or two (in which case I usually just set them on optical slave). I do this in portrait/fashion type work. The pre-flash on the P-TTL mode is killing me. I bought this flash because I had been using a Nikon SB800 on manual mode, but wanted to make things a little faster and easier by getting TTL coupled flash for my 645D. The preflash is killing me in two ways - it causes a shutter actuation delay that, while slight, means something in the way I shoot - I can miss what I want. The second way it's killing me is that I can't fire studio lights via optical slave because the preflash prematurely triggers the light. I know the workarounds, I have pocket wizards to fire the profotos, but I use the on camera flash or natural light the most. I got the AF540 GZII to make shooting easier and more seamless as I move around a shoot (so I am not calculating flash ratios as I switch lenses and move my distance from subject etc), not because I needed another flash. I called the Pentax service in NC or wherever and chatted with a very nice guy who was as confused as I was and ultimately offered no help. He said he would ask around the shop and email the next day with a definitive answer. Never happened. Is there any way to get ttl functionality out of this flash without that damned preflash? If so, what terrible design. If everyone else can do it why can't Pentax?

03-02-2016, 11:09 AM	#6
Kameraten Senior Member Join Date: Dec 2007 Location: Finland Photos: Gallery Posts: 214	Manual mode I would go for manual mode. I assume the 645D behaves like other Pentaxes so when you set it to M you can set the AF540 to M too, and then you can regulate it's output to whatever fraction is needed to trigger your slaves. Then there will be no pre-flash. With the camera in M you might want also to set the flash sync on-camera to second curtain. That way you will be able to set shutter and aperture to what the ambient light suggests just by pressing the green button. And you might want to modify the way the green button works with M so that it for example works like aperture priority. I think you'll find that option in the menus.

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03-02-2016, 09:58 AM	#2
Scintilla Veteran Member Join Date: Oct 2013 Photos: Gallery \| Albums Posts: 347	Originally posted by petrakka Is there any way to get ttl functionality out of this flash without that damned preflash? If so, what terrible design. If everyone else can do it why can't Pentax? I thought that all digital-era TTL flash schemes required a preflash, not just Pentax's? The non-mark-II versions of the 360 and 540 flashes have auto thyristor mode, which I don't believe uses a preflash. It does, however, require you to set the ISO and aperture yourself on the flash.

03-02-2016, 10:19 AM	#3
enoeske Veteran Member Join Date: Jul 2009 Location: Surprise, Az Photos: Gallery Posts: 2,136	Originally posted by petrakka portrait/fashion work In automatic mode? Dude, you have a 645D, a studio, studio lights and pocket wizards! Why on earth are you using a P-TTL flash in that setup at all? What were you hoping to make easier or speed up by using it?

03-02-2016, 11:06 AM	#4
pathdoc Pentaxian Join Date: Mar 2015 Photos: Gallery \| Albums Posts: 6,381	The only Pentax digital camera with true TTL flash capability that I know of was the original *ist-D.

03-02-2016, 11:07 AM - 1 Like	#5
CarlJF Veteran Member Join Date: Sep 2014 Location: Quebec City Posts: 1,185	The P in P-TTL stands for "preflash". So, by definition, there's always a preflash in P-TTL. And it will be the same situation with Canon or Nikon. They're all based on a preflash light measurement... This is how modern flashes work, for all manufacturers, and also one of the reasons many people still prefer to use their flashes in manual mode instead of TTL. If you don't want a preflash, you should use the flash in manual mode. There's no way around it.

03-02-2016, 11:30 AM	#7
CarlJF Veteran Member Join Date: Sep 2014 Location: Quebec City Posts: 1,185	Why are you mixing TTL and manual studio flashes ? It doesn't make much sense to me. How do you expect the camera to control the power output of the studio flashes ? Which is the point of using TTL flashes... You should use all your flashes in manual or TTL, but not mix fladhes working in different modes...

03-02-2016, 11:53 AM	#8
petrakka Forum Member Join Date: Feb 2016 Location: Chicago Posts: 91 Original Poster	Originally posted by enoeske In automatic mode? Dude, you have a 645D, a studio, studio lights and pocket wizards! Why on earth are you using a P-TTL flash in that setup at all? What were you hoping to make easier or speed up by using it? I don't have a studio, I shoot all location work. I don't off camera strobe for the most part. I usually prefer natural light, and my second preference is hard, bare on camera flash. I have the profotos for when client needs demand it, but in general the more gear on a shoot (including lights) the less happy I am. When I am shooting a moving subject, or we have to do multiple set ups, moving from location to location with TTL I can set it how I want and get pretty consistent look from space to space. A lot of portrait work I like is sort of 'in-between' moments, which the pre-flash can cause me to miss. On editorial jobs my time is often quite limited. It is just a preference thing. This is just a question I asked about how to get something to work, not about justifying the way I like to work. ---------- Post added 03-02-16 at 01:06 PM ---------- Originally posted by CarlJF Why are you mixing TTL and manual studio flashes ? It doesn't make much sense to me. How do you expect the camera to control the power output of the studio flashes ? Which is the point of using TTL flashes... You should use all your flashes in manual or TTL, but not mix fladhes working in different modes... It doesn't need to make sense to you, but if you want more info, I have an assistant to control the output of the monoheads. I use the on camera flash TTL to control how much light I want from on camera, within reason. I use the full scope of the +/- exposure compensation of the TTL and when using this method on Nikon or Sony it has worked fine, but for other reasons I prefer to use my Pentax whenever possible for photographing people. I know how it all works, but you work for long enough and you find how you prefer to work and what works best for you, even if it's not the way most people may prefer to work. I just was trying to figure out if there was a way to kill the preflash.

03-02-2016, 12:07 PM	#9
enoeske Veteran Member Join Date: Jul 2009 Location: Surprise, Az Photos: Gallery Posts: 2,136	Originally posted by petrakka I don't have a studio, I shoot all location work. I don't off camera strobe for the most part. I usually prefer natural light, and my second preference is hard, bare on camera flash. I have the profotos for when client needs demand it, but in general the more gear on a shoot (including lights) the less happy I am. When I am shooting a moving subject, or we have to do multiple set ups, moving from location to location with TTL I can set it how I want and get pretty consistent look from space to space. A lot of portrait work I like is sort of 'in-between' moments, which the pre-flash can cause me to miss. On editorial jobs my time is often quite limited. It is just a preference thing. This is just a question I asked about how to get something to work, not about justifying the way I like to work. Well, there is no way to disable the P-TTL preflash. Neither is there a way to disable the preflash on Canon's i-TTL or Nikons flashes. You can either use manual flash which does not use a preflash, or get used to the preflash. As CarlJF said, though, I wouldn't mix P-TTL and manual strobes. Its just asking for trouble.

03-02-2016, 12:08 PM	#10
petrakka Forum Member Join Date: Feb 2016 Location: Chicago Posts: 91 Original Poster	Originally posted by CarlJF The P in P-TTL stands for "preflash". So, by definition, there's always a preflash in P-TTL. And it will be the same situation with Canon or Nikon. They're all based on a preflash light measurement... This is how modern flashes work, for all manufacturers, and also one of the reasons many people still prefer to use their flashes in manual mode instead of TTL. If you don't want a preflash, you should use the flash in manual mode. There's no way around it. Thanks. Interestingly I have not had this problem with the SB-800 on a Nikon or the Nissin i40 on my Sony. Maybe it's that the Pentax preflash is much slower and I didn't notice it on the other cameras, not sure. But okay, so I am stuck with this. Good to know. ---------- Post added 03-02-16 at 01:10 PM ---------- Originally posted by Kameraten I would go for manual mode. I assume the 645D behaves like other Pentaxes so when you set it to M you can set the AF540 to M too, and then you can regulate it's output to whatever fraction is needed to trigger your slaves. Then there will be no pre-flash. With the camera in M you might want also to set the flash sync on-camera to second curtain. That way you will be able to set shutter and aperture to what the ambient light suggests just by pressing the green button. And you might want to modify the way the green button works with M so that it for example works like aperture priority. I think you'll find that option in the menus. Yea, this is what I have been doing, and it is fine. It just can kill the vibe/slow down the shoot some, which is why I want the TTL with no preflash. Basically the more shooting and less fiddling with other controls the happier I am. ---------- Post added 03-02-16 at 01:15 PM ---------- Originally posted by enoeske Well, there is no way to disable the P-TTL preflash. Neither is there a way to disable the preflash on Canon's i-TTL or Nikons flashes. You can either use manual flash which does not use a preflash, or get used to the preflash. As CarlJF said, though, I wouldn't mix P-TTL and manual strobes. Its just asking for trouble. I've been fine doing this with other systems for awhile, it hasn't caused me trouble, but alright? I didn't ask for advice on how to shoot, which, if I did then cool, but I just asked if preflash could be disabled.

03-02-2016, 12:39 PM	#11
CarlJF Veteran Member Join Date: Sep 2014 Location: Quebec City Posts: 1,185	Originally posted by petrakka Thanks. Interestingly I have not had this problem with the SB-800 on a Nikon or the Nissin i40 on my Sony. Maybe it's that the Pentax preflash is much slower and I didn't notice it on the other cameras, not sure. But okay, so I am stuck with this. Good to know. Are you sure you were not using the SB-800 in manual mode ? As far as I know, people using Canon or Nikon have the exaxt same issue. The workaround should be the same: using radio trigger or sync cable with the manual flashes. With the radio triggers, you can use a p-ttl cable as a kind of "hot shoe splitter", putting the radio trigger on one end and the ttl flash on the other. Obviously, using a flash bracket would be quite useful to support either the flash or trigger. I haven't tried it, but this should work. I don't know if the 645 has a sync port, but if so, it could also probably be used to trigger the remote flashes directly or with the radio trigger, by pluging it on the sync port instead of the hotshoe....

03-02-2016, 12:46 PM - 1 Like	#12
mcgregni Veteran Member Join Date: Sep 2012 Location: Surrey, England Posts: 2,603	As said by others, if you set a dedicated system flash to its 'TTL' mode, then it must use a pre-flash .... same for all makes, and there would be no technical purpose to disabling the pre-flash when in the TTL mode, because clearly then the TTL mode could not function. The real issue here is the method you are using to trigger your studio lights, which seems to be optical triggering from the on-camera flash. Unless your off-camera lights have a delay function that can be programmed to delay the flash until the exposure, ignoring the pre-flash, then I don't see how you can avoid your problem. A number of 'speedlight' type flashes, including the Pentax models, have 'Slave Modes' (S1 / S2) which allow the flash to be set to ignore the pre-flash from a dedicated controller flash .... clearly this is not the case for your manual studio lights. If you cannot programme a delay into your slave flashes, then if you want to use a P-TTL flash on the camera in combination with manual slaves, I think you will need to use a radio trigger system, with the P-TTL flash on top of the trigger. I do this with my Pentax flashes and a Cactus V6 ..... this unit has a 'TTL Pass-through' mode allowing the Pentax flash on top of the V6 to behave exactly as if it is mounted directly to the camera. The pre-flash still occurs, but it comes before the triggering of the slave from the V6, which of course corresponds to the actual exposure and main flash from the Pentax, so all flashes sync without any delay.

03-02-2016, 01:00 PM	#13
petrakka Forum Member Join Date: Feb 2016 Location: Chicago Posts: 91 Original Poster	Originally posted by CarlJF Are you sure you were not using the SB-800 in manual mode ? As far as I know, people using Canon or Nikon have the exaxt same issue. The workaround should be the same: using radio trigger or sync cable with the manual flashes. With the radio triggers, you can use a p-ttl cable as a kind of "hot shoe splitter", putting the radio trigger on one end and the ttl flash on the other. Obviously, using a flash bracket would be quite useful to support either the flash or trigger. I haven't tried it, but this should work. I don't know if the 645 has a sync port, but if so, it could also probably be used to trigger the remote flashes directly or with the radio trigger, by pluging it on the sync port instead of the hotshoe.... So, this workaround - yea, that's what I was thinking, but I don't really want to go there. Might have to, we'll see. This thread might make it seem like I'm pretty clueless about the new technology speedlights, and basically, I am. I have used pocket wizards, studio strobes and Vivitar 285's up until a few years ago, so for me it was always all manual and all numbers, and usually all off camera. But I picked up an SB800 by chance a few years back and started using the TTL mode and really took playing with on camera flash, and I really took to it - but I only just started trying to do this with the Pentax in the past year, and just resorting to using the SB-800 in Manual mode on my Pentax. I figured TTL would work as smoothly on the Pentax as the Nikon but, well, nope. If they all do the preflash, then I am stumped. I have definitely used my SB800 a ton in TTL getting the results I wanted to. Maybe the preflash on it is just imperceptible compared to the Pentax. The main thing I don't like the preflash for is more the delay it causes then the studio light situation. If I used the SB800 with studio lights I guess it must have been in manual. I just have never noticed a preflash on the SB800 in ttl mode. But I rarely mix them because as I stated, I usually prefer just the on camera flash, and that is second to the natural light I most often use. The last time I actually mixed on camera flash with the profotos (besides with the Pentax and the SB800 in manual mode on it, which is what I have mostly done up until I got this 540) was probably almost a year ago. I've only used the profotos a few times in the past year though. I've just had a series of shoots come up in the past few weeks where I needed to mix the two, and it was fine I just went manual mode like I am used to, but wondered if I could work with it in exactly the way I had envisioned - which appears not to be the case. ---------- Post added 03-02-16 at 02:22 PM ---------- Ok, you guys had me thinking I was going nuts so I just got out my flashes for everything - Sony, Nikon and Pentax and tried it all. I think I can see the preflash from the Nikon and the Sony in TTL, but it is basically imperceptible. It's quite fast. On the Pentax, it is quite slow, but I also have a strangely sticky mirror on my 645D - sticky enough to even when you shoot at 1/125 you hear distinctly the mirror opening, then closing - I am thinking that it is maybe the sticky mirror that the preflash is syncing to and making it seem so separate and noticeable. The strange thing though - the exposures are still good, it's not like I am getting the ambient light of a slow exposure. I'm not sure what's going on.

03-02-2016, 01:31 PM - 1 Like	#14
CarlJF Veteran Member Join Date: Sep 2014 Location: Quebec City Posts: 1,185	Were you using the SB-800 on an film body or a digital one ? With film, there's no preflash... I'm asking because doing a google search shows up a lot of people having the same delay problem with the Nikon system... Have you checked the flash is set on first curtain sync ? Maybe it's set on second curtain sync, making the delay even more obvious...

03-02-2016, 01:41 PM	#15
petrakka Forum Member Join Date: Feb 2016 Location: Chicago Posts: 91 Original Poster	Originally posted by CarlJF Were you using the SB-800 on an film body or a digital one ? With film, there's no preflash... I'm asking because doing a google search shows up a lot of people having the same delay problem with the Nikon system... Have you checked the flash is set on first curtain sync ? Maybe it's set on second curtain sync, making the delay even more obvious... SB 800 on a D-800 (digital) - and I just tried it out and it's still seamless. (Haven't gotten that d800 for awhile!). But yea, I can't answer why I felt like my Nikon set up always worked with my Acutes, but I've never had an issue with getting stuff to look how I want. All I can think is that, when I brought in the Acutes I must have been in manual mode despite my thinking that I wasn't. That or I have super powers, but I'm pretty sure I don't. Re: the curtain, I double checked it, but yea it's definitely on first curtain sync - I really think it might have to do with the mirror on my 645D. Maybe I'll see if there's a shop that carries a K5 or something around here that I can try my flash on and see if it works more quickly on that. Things were so much simpler when I could just use my Contax G2 and Hasselblad and it all just did the few things it was supposed to do. Sigh. This is even making me long for the days of sync cords and light meters.