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Forums Lobby MASTER YOUR TOOLS - Hardware & Software Nikon Speedlights & Lighting topic #61699
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Subject: "Strange observation of Speedlight operation" Previous topic | Next topic
Craig Bennett Silver Member Nikonian since 28th Oct 2012Wed 26-Jun-13 07:50 PM
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"Strange observation of Speedlight operation"


Albuquerque, US
          

Something that has puzzled me in the past, but since I updated my PW firmware yesterday and ran tests, decided to narrow down this strange behavior.

When using a SB-9xx for a Master on camera, turn off remote lights via the menu, but leave the Master flash in TTL mode. Take a photograph. Now, turn the flash to normal (non-master mode) and keep it in standard TTL mode. Take the same photograph (under same conditions). To get the same exposure (and correct one) when the flash is in Master mode I have to give it + .7 FEC. I cannnot see any reason why there should be any difference between Master in standard TTL mode and Flash in standard TTL mode?

In the past, I noticed this during wedding receptions when I turned off my remotes and used the camera's flash for main light. I though it was the PocketWizard, but it turns out the flash behaves the same regardless of communications used.

If I turn on the remotes, the flash on the camera in TTL mode seems to operate correctly. Though I need to make additional tests to verify this.

Anyone have an explanation for why Master TTL flash mode and Non-Master TTL flash mode are different?

  

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Replies to this topic
Subject Author Message Date ID
Reply message RE: Strange observation of Speedlight operation
Bravozulu Silver Member
27th Jun 2013
1
Reply message RE: Strange observation of Speedlight operation
Arkayem Moderator
27th Jun 2013
3
Reply message RE: Strange observation of Speedlight operation
Arkayem Moderator
27th Jun 2013
2
Reply message RE: Strange observation of Speedlight operation
Craig Bennett Silver Member
14th Jul 2013
4
     Reply message RE: Strange observation of Speedlight operation
ScottChapin Moderator
15th Jul 2013
5
          Reply message RE: Strange observation of Speedlight operation
Craig Bennett Silver Member
22nd Jul 2013
6

Bravozulu Silver Member Nikonian since 04th Jun 2012Thu 27-Jun-13 03:15 PM
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#1. "RE: Strange observation of Speedlight operation"
In response to Reply # 0


Los Angeles, US
          

I shoot a lot in Manual Mode. TTL is notoriously inconsistent. Things like color, subject contrast cause gyrations in exposure. And TTl-BL is worse in this regard, if I'm not mistaken.


I know, it sounds crazy to dump all that money into a high tech Nikon speedlight only to disable the automated features.

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Visit my Nikonians gallery.

  

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Arkayem Moderator Awarded for his high level skills in flash photography Charter MemberThu 27-Jun-13 06:29 PM
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#3. "RE: Strange observation of Speedlight operation"
In response to Reply # 1


Richmond Hill, GA (Savannah), US
          

>I shoot a lot in Manual Mode. TTL is notoriously
>inconsistent. Things like color, subject contrast cause
>gyrations in exposure. And TTl-BL is worse in this regard, if
>I'm not mistaken.
>
>
>I know, it sounds crazy to dump all that money into a high
>tech Nikon speedlight only to disable the automated features.
>

TTL-BL is very accurate if used properly. The main thing to know is that the camera must be set for a proper exposure of the ambient when using BL. This is easiest to accomplish by setting the camera to P mode, so it will automatically set the exposure correctly. Then, BL adds just a small amount of fill flash to brighten shadows.

TTL-BL cannot be selected when using wireless CLS.

Russ
Nikonian Team Member
Russell MacDonald Photography
Nikon CLS Practical Guide

  

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Arkayem Moderator Awarded for his high level skills in flash photography Charter MemberThu 27-Jun-13 06:21 PM
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#2. "RE: Strange observation of Speedlight operation"
In response to Reply # 0


Richmond Hill, GA (Savannah), US
          

>Something that has puzzled me in the past, but since I
>updated my PW firmware yesterday and ran tests, decided to
>narrow down this strange behavior.
>
>When using a SB-9xx for a Master on camera, turn off remote
>lights via the menu, but leave the Master flash in TTL mode.
>Take a photograph. Now, turn the flash to normal (non-master
>mode) and keep it in standard TTL mode. Take the same
>photograph (under same conditions). To get the same exposure
>(and correct one) when the flash is in Master mode I have to
>give it + .7 FEC. I cannnot see any reason why there should
>be any difference between Master in standard TTL mode and
>Flash in standard TTL mode?
>
>In the past, I noticed this during wedding receptions when I
>turned off my remotes and used the camera's flash for main
>light. I though it was the PocketWizard, but it turns out the
>flash behaves the same regardless of communications used.
>
>If I turn on the remotes, the flash on the camera in TTL mode
>seems to operate correctly. Though I need to make additional
>tests to verify this.
>
>Anyone have an explanation for why Master TTL flash mode and
>Non-Master TTL flash mode are different?

When in wireless CLS mode, the flashes all fire at lower than full measured power, because they assume there will be other flashes fired, and it is a way to reduce overexposure. This is one example where wireless CLS is not as smart as some people think.

Russ
Nikonian Team Member
Russell MacDonald Photography
Nikon CLS Practical Guide

  

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Craig Bennett Silver Member Nikonian since 28th Oct 2012Sun 14-Jul-13 02:23 PM
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#4. "RE: Strange observation of Speedlight operation"
In response to Reply # 2


Albuquerque, US
          


>
>When in wireless CLS mode, the flashes all fire at lower than
>full measured power, because they assume there will be other
>flashes fired, and it is a way to reduce overexposure. This is
>one example where wireless CLS is not as smart as some people
>think.
>
>Russ

Hi Russ, I agree with your statement on the CLS system and understand (and agree with) why it behaves like this. However what caught me off guard was my thinking it should be "smart" enough to know when in Master mode that when all remotes (Groups) are off, it should behave like it does in standard TTL mode.

The Master flash is not part of a group, it acts alone, so it should not assume (it knows) there will not be other flashes firing when all groups are off. That is all I'm saying. To me, this is a bug in their programming.

This made me think through my use though. I now just turn the Master flash to standard "On" and use it normally. The PocketWizard MiniTT1 transmitter passes the communications from camera to flash with no issues and I don't have to take it out of the signal path. When I need the remotes firing again, I switch it back to Master. Seems obvious in retrospect.

Regards,
Craig

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ScottChapin Moderator Awarded for his high level skills in various areas, including Aviation and Birds Photography Charter MemberMon 15-Jul-13 09:50 AM
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#5. "RE: Strange observation of Speedlight operation"
In response to Reply # 4


Powder Springs, US
          

Craig,

As I understand it, the groups are metered individually and not collectively. The CLS system is not advanced enough to know how much of the final exposure each group is contributing.

It doesn't know whether a group is firing head on, or only illuminating part of the subject from the side. The later would reflect less light, though it might be firing at the same power level.

Two groups firing head on, for example, will tend to be overexposed. Fortunately, we can chimp.

Scott Chapin
Powder Springs, GA, USA
Nikonians Team Member

  

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Craig Bennett Silver Member Nikonian since 28th Oct 2012Mon 22-Jul-13 03:54 AM
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#6. "RE: Strange observation of Speedlight operation"
In response to Reply # 5


Albuquerque, US
          

>Craig,
>
>As I understand it, the groups are metered individually and
>not collectively. The CLS system is not advanced enough to
>know how much of the final exposure each group is
>contributing.
>
>It doesn't know whether a group is firing head on, or only
>illuminating part of the subject from the side. The later
>would reflect less light, though it might be firing at the
>same power level.
>
>Two groups firing head on, for example, will tend to be
>overexposed. Fortunately, we can chimp.
Hi Scott,
I agree with what you are saying. I certainly understand the limitations on CLS, which in fact as a system goes, is pretty ingenious.

All I'm saying is that I am surprised that when the Master has all the groups turned off and only the Master is on, then I would think the flash system would default back to simple straight TTL, but it does not.

I think it is a bug, it just make no sense to me. I wish Nikon was more open on their theory of operation and design decisions that go into their product.

Regards,
Craig

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