2 Godox FLashes as a commander and 1 As a slave in TTL how to connect?

[A_SCY]

Hello guys, I have a shoot in two weeks and I will use one of my flashes as a rim light, one as the main key light on-camera, and I will keep one extra flash as backup. I have a Godox V1, a TT685 (first version), and a TT685 II. I want to use the Godox V1 as my main flash on the camera acting as the commander, and the TT685 (v1) as a slave rim light in TTL mode. I will keep the TT685 II as backup. In case the V1 fails, I want to quickly mount the TT685 II on-camera and continue shooting without reprogramming anything. The issue is that I am having trouble getting the TT685 (v1) to stay consistently connected as a slave. I set the TT685 (v1) to slave mode, set it to Channel 1 and Group A. On the V1 and also on the TT685 II, I go into the wireless menu, select Channel 1, and set Group A to TTL. Sometimes it connects and fires correctly, showing “Nikon” on the slave screen which means it’s synced, but it only works if I press the test flash button on both flashes nearly at the same time, and even then not always. I also tried turning off one commander flash when using the other, because I read that having two commanders on can cause issues, but still the connection is not reliable. What I really want is a stable connection where the TT685 (v1) slave stays paired and ready, and most importantly, I want it so when I turn off the flashes and turn them back on again, they automatically reconnect without me needing to press buttons again or set anything up. I need this to work smoothly because I want to focus on the shoot, not troubleshooting flashes. Any help or tips would be appreciated, especially if someone has experience with mixing Godox V1, TT685 v1, and TT685 II in the same wireless setup. Thank you!

 

[tugwilson]

Your V1 has a "channel scan" function this finds the best channels to use at your location. Use that to pick a channel to use. Channel 1 is everybody's default channel and is therefore a poor choice.

Generally having two triggers live isn't a problem. In groups shoots we often have three or four.

It sounds like you are having radio interference issues. Channel scan should fix that.

If the problem remains please post photographs of the rear screen of all 3 of your speedlights.

 

[A_SCY]

Your V1 has a "channel scan" function this finds the best channels to use at your location. Use that to pick a channel to use. Channel 1 is everybody's default channel and is therefore a poor choice.

Generally having two triggers live isn't a problem. In groups shoots we often have three or four.

It sounds like you are having radio interference issues. Channel scan should fix that.

If the problem remains please post photographs of the rear screen of all 3 of your speedlights.

Thank you so so much for your help i will test it out and let you know

 

[A_SCY]

Your V1 has a "channel scan" function this finds the best channels to use at your location. Use that to pick a channel to use. Channel 1 is everybody's default channel and is therefore a poor choice.

Generally having two triggers live isn't a problem. In groups shoots we often have three or four.

It sounds like you are having radio interference issues. Channel scan should fix that.

If the problem remains please post photographs of the rear screen of all 3 of your speedlights.

Thank you so so much for your help i will test it out and let you know

Thank you so much, I just checked everything, I ran a scan and it showed several channels, I selected Channel 20 and now everything seems to be working fine, but I’m wondering if I should do the scan again at the actual photoshoot location or if it’s okay to keep the current setting since the distance isn’t far, my current setup will be TT685 as a rim light in TTL slave mode, the V1 as my main flash and the second TT685 II as backup, both set in commander TTL mode, so if I power them off and on again they should still sync properly, right, this system is using radio TTL and not optical, correct, and in TTL mode do the slave flashes also send a pre-flash to help the camera calculate exposure or is it just the master doing it, also normally the slave flash should take the signal instantly when I press the shutter or test button on the commander flash, right, I’ll be doing my first baptism soon and since the main flash will be on-camera and quite close to the subject I’m planning to set the TTL exposure compensation to -1 EV to prevent overexposure, I haven’t seen the church lighting with the lights on yet but I did visit the location, my plan is to shoot mostly at f/4 using the Nikon 24-70mm, with shutter speed 1/125s for general shots and 1/250s for the baptism itself, ISO set at 800, and I’ll also be using the rim flash for separation.

 

[tugwilson]

You should always do a channel scan before a shoot even if it's at home the wireless environment can change from day to day.

I'd practice at home first to see what settings are best. Multi light TTL can be a bit tricky. My preference would be that the rim light at least should be in Manual mode. The power for a rim light should not change unless the ambient does.

 

[Gato Amarillo]

-----

Thank you so much, I just checked everything, I ran a scan and it showed several channels, I selected Channel 20 and now everything seems to be working fine, but I’m wondering if I should do the scan again at the actual photoshoot location or if it’s okay to keep the current setting since the distance isn’t far, ----

YES! Scan again. Every location is different.

Just to show how strange it can get, in the small studio I sometimes use the channels that show best at the camera position are completely different from the best channels at the fill light position. If I set based on the camera position the fill light is not at all reliable.

Gato

 

[fotowbert]

Thank you so much, I just checked everything, I ran a scan and it showed several channels, I selected Channel 20 and now everything seems to be working fine, but I’m wondering if I should do the scan again at the actual photoshoot location or if it’s okay to keep the current setting since the distance isn’t far, my current setup will be TT685 as a rim light in TTL slave mode, the V1 as my main flash and the second TT685 II as backup, both set in commander TTL mode, so if I power them off and on again they should still sync properly, right, this system is using radio TTL and not optical, correct, and in TTL mode do the slave flashes also send a pre-flash to help the camera calculate exposure or is it just the master doing it, also normally the slave flash should take the signal instantly when I press the shutter or test button on the commander flash, right, I’ll be doing my first baptism soon and since the main flash will be on-camera and quite close to the subject I’m planning to set the TTL exposure compensation to -1 EV to prevent overexposure, I haven’t seen the church lighting with the lights on yet but I did visit the location, my plan is to shoot mostly at f/4 using the Nikon 24-70mm, with shutter speed 1/125s for general shots and 1/250s for the baptism itself, ISO set at 800, and I’ll also be using the rim flash for separation.

Based upon my Godox for Nikon TTL testing I have concluded that when there are multiple groups in TTL mode each group must individually preflash. This testing was with 2 and then 3 off-camera TTL groups controlled by the XProII-N.

I came to my conclusion after noticing that the Nikon TTL system as reported via TCM on the XProII can identify which group I have moved in the following multiple TTL group scenario.

Starting with a single TT685II in groups A and B both positioned the same distance from a uniform tone test target TCM reports similar power fractions for each group. Now move group A light to twice the distance and TCM reports group A power has increased while B is unchanged. The power increase roughly follows the Inverse Square Law which makes sense as the TTL system is trying to maintain the same exposure on the target.

I repeated the test with 3 TT685II and groups A, B, and C first moving one light and then another. Each time the TTL system only changed the power fraction on the group that was moved.

I don't know if this behavior would also apply to the on-camera group M in addition to groups A and B when an on-camera flash is being used as radio transmitter but I suspect it does.

EDITED to add: I couldn't test this because the TCM function on the TT685II-N is not available when the unit is in transmitter mode.

• John

--
"[If you don't sweat the details] the magic doesn't work." Brooks, F. P., The Mythical Man-Month, Addison-Wesley, 1975, page 8.

 

[A_SCY]

Thank you so much, I just checked everything, I ran a scan and it showed several channels, I selected Channel 20 and now everything seems to be working fine, but I’m wondering if I should do the scan again at the actual photoshoot location or if it’s okay to keep the current setting since the distance isn’t far, my current setup will be TT685 as a rim light in TTL slave mode, the V1 as my main flash and the second TT685 II as backup, both set in commander TTL mode, so if I power them off and on again they should still sync properly, right, this system is using radio TTL and not optical, correct, and in TTL mode do the slave flashes also send a pre-flash to help the camera calculate exposure or is it just the master doing it, also normally the slave flash should take the signal instantly when I press the shutter or test button on the commander flash, right, I’ll be doing my first baptism soon and since the main flash will be on-camera and quite close to the subject I’m planning to set the TTL exposure compensation to -1 EV to prevent overexposure, I haven’t seen the church lighting with the lights on yet but I did visit the location, my plan is to shoot mostly at f/4 using the Nikon 24-70mm, with shutter speed 1/125s for general shots and 1/250s for the baptism itself, ISO set at 800, and I’ll also be using the rim flash for separation.

Based upon my Godox for Nikon TTL testing I have concluded that when there are multiple groups in TTL mode each group must individually preflash. This testing was with 2 and then 3 off-camera TTL groups controlled by the XProII-N.

I came to my conclusion after noticing that the Nikon TTL system as reported via TCM on the XProII can identify which group I have moved in the following multiple TTL group scenario.

Starting with a single TT685II in groups A and B both positioned the same distance from a uniform tone test target TCM reports similar power fractions for each group. Now move group A light to twice the distance and TCM reports group A power has increased while B is unchanged. The power increase roughly follows the Inverse Square Law which makes sense as the TTL system is trying to maintain the same exposure on the target.

I repeated the test with 3 TT685II and groups A, B, and C first moving one light and then another. Each time the TTL system only changed the power fraction on the group that was moved.

I don't know if this behavior would also apply to the on-camera group M in addition to groups A and B when an on-camera flash is being used as radio transmitter but I suspect it does.

EDITED to add: I couldn't test this because the TCM function on the TT685II-N is not available when the unit is in transmitter mode.

• John

Thank you for your answer.
If I understand correctly, each TTL slave flash can independently adjust its own power to achieve the correct exposure, but they also work together to ensure accurate overall exposure for the entire image.

 

[A_SCY]

You should always do a channel scan before a shoot even if it's at home the wireless environment can change from day to day.

I'd practice at home first to see what settings are best. Multi light TTL can be a bit tricky. My preference would be that the rim light at least should be in Manual mode. The power for a rim light should not change unless the ambient does.

Thank you very much for your answer , i prefer to use it as A TTl because there is times that it will be not just a rim flash because maybe i will move it according the situation so i think i will go with TTL

 

[A_SCY]

-----

Thank you so much, I just checked everything, I ran a scan and it showed several channels, I selected Channel 20 and now everything seems to be working fine, but I’m wondering if I should do the scan again at the actual photoshoot location or if it’s okay to keep the current setting since the distance isn’t far, ----

YES! Scan again. Every location is different.

Just to show how strange it can get, in the small studio I sometimes use the channels that show best at the camera position are completely different from the best channels at the fill light position. If I set based on the camera position the fill light is not at all reliable.

Gato

Thank you for your previous answer. I have a few follow-up questions about using the Godox V1 and TT685 flashes.

Last time, I manually set the flash to channel 20. When I rescan, channel 20 still appears, so I just leave it on that channel and everything works fine. If I do the same in the church and channel 20 is on the list (even if it's not the first one shown), can I still leave it set to 20 and expect it to work correctly?

Now, regarding the V1 as a commander:
Do I have to keep the screen on the Group view (showing groups A, B, C, D, etc.) in order for it to trigger the TT685 as a slave? I noticed that when I switch the V1 to the main TTL screen—where I can adjust flash exposure compensation—the slave TT685 doesn't fire.

So, is this the correct workflow?

1. First, go to the main TTL screen on the V1 and set the flash exposure compensation (e.g., -1).
2. Then switch back to the Group screen to trigger the slave TT685 (which I’ve assigned to Group A).

Is this how it's supposed to work? I originally thought I could stay on the main TTL screen, adjust exposure compensation easily, and still trigger the slave flash, but it seems that’s not the case.

One more question:
If I place the TT685 as a slave on a light stand in one fixed position in the baptism area, and later during the ceremony I follow the priest toward the church entrance—being around 15–20 meters away from the slave flash—will the V1 (on-camera) still trigger it reliably? I understand that for the on-camera flash (V1) to function with the slave, they must maintain wireless communication. Will that distance be too much, or should it still work fine?

 

[Gato Amarillo]

Thank you so much, I just checked everything, I ran a scan and it showed several channels, I selected Channel 20 and now everything seems to be working fine, but I’m wondering if I should do the scan again at the actual photoshoot location or if it’s okay to keep the current setting since the distance isn’t far, ----

YES! Scan again. Every location is different.

Just to show how strange it can get, in the small studio I sometimes use the channels that show best at the camera position are completely different from the best channels at the fill light position. If I set based on the camera position the fill light is not at all reliable.

Gato

Thank you for your previous answer. I have a few follow-up questions about using the Godox V1 and TT685 flashes.

Last time, I manually set the flash to channel 20. When I rescan, channel 20 still appears, so I just leave it on that channel and everything works fine. If I do the same in the church and channel 20 is on the list (even if it's not the first one shown), can I still leave it set to 20 and expect it to work correctly?

Probably yes, it will most likely work. Especially if it's high on the list.

Now, regarding the V1 as a commander:
Do I have to keep the screen on the Group view (showing groups A, B, C, D, etc.) in order for it to trigger the TT685 as a slave? I noticed that when I switch the V1 to the main TTL screen—where I can adjust flash exposure compensation—the slave TT685 doesn't fire.

So, is this the correct workflow?

1. First, go to the main TTL screen on the V1 and set the flash exposure compensation (e.g., -1).
2. Then switch back to the Group screen to trigger the slave TT685 (which I’ve assigned to Group A).

Is this how it's supposed to work? I originally thought I could stay on the main TTL screen, adjust exposure compensation easily, and still trigger the slave flash, but it seems that’s not the case.

I cannot answer, not being familiar with the V1

One more question:
If I place the TT685 as a slave on a light stand in one fixed position in the baptism area, and later during the ceremony I follow the priest toward the church entrance—being around 15–20 meters away from the slave flash—will the V1 (on-camera) still trigger it reliably? I understand that for the on-camera flash (V1) to function with the slave, they must maintain wireless communication. Will that distance be too much, or should it still work fine?

Probably, depending on how much interference there is. I think Godox claims 100 meter range, but that's probably under ideal conditions. I'd guess 1/2 or less of that is more realistic. Keep in mind there can be a lot of wifi in a church -- probably an internet router, then sound or video systems, security systems, lighting control, and so on.

--
It's a work in progress, but the website is up and running:
https://jrsprawls.smugmug.com/
.
Personal pictures, road trips, rural nostalgia, and kitty cats:
https://www.instagram.com/j.r.sprawls/

 

[Gato Amarillo]

---------

Now, regarding the V1 as a commander:
Do I have to keep the screen on the Group view (showing groups A, B, C, D, etc.) in order for it to trigger the TT685 as a slave? I noticed that when I switch the V1 to the main TTL screen—where I can adjust flash exposure compensation—the slave TT685 doesn't fire.

So, is this the correct workflow?

1. First, go to the main TTL screen on the V1 and set the flash exposure compensation (e.g., -1).
2. Then switch back to the Group screen to trigger the slave TT685 (which I’ve assigned to Group A).

Is this how it's supposed to work? I originally thought I could stay on the main TTL screen, adjust exposure compensation easily, and still trigger the slave flash, but it seems that’s not the case.

I cannot answer, not being familiar with the V1

Another thought -- if the V1 works like my TT350 you set the compensation on the group screen. Using the TT350 as controller it shows a Group M (master, I suppose), then the remote flashes are A,B, and C. To set the compensation on the master I choose M on the group screen, press set, and dial in the compensation.

Again, I don't know the V1, so don't know if that applies.

 

[A_SCY]

---------

Now, regarding the V1 as a commander:
Do I have to keep the screen on the Group view (showing groups A, B, C, D, etc.) in order for it to trigger the TT685 as a slave? I noticed that when I switch the V1 to the main TTL screen—where I can adjust flash exposure compensation—the slave TT685 doesn't fire.

So, is this the correct workflow?

1. First, go to the main TTL screen on the V1 and set the flash exposure compensation (e.g., -1).
2. Then switch back to the Group screen to trigger the slave TT685 (which I’ve assigned to Group A).

Is this how it's supposed to work? I originally thought I could stay on the main TTL screen, adjust exposure compensation easily, and still trigger the slave flash, but it seems that’s not the case.

I cannot answer, not being familiar with the V1

Another thought -- if the V1 works like my TT350 you set the compensation on the group screen. Using the TT350 as controller it shows a Group M (master, I suppose), then the remote flashes are A,B, and C. To set the compensation on the master I choose M on the group screen, press set, and dial in the compensation.

Again, I don't know the V1, so don't know if that applies.

Hello,

Yes, you are right!

And thank you !!

I just checked it now. I didn’t even notice that it was showing an "M" there, so you’re correct that you can set the exposure compensation there, which is great.

The only other thing is to check the channels being used in the church and set the flashes to suitable channels.

I also have another question: If the flash is set on scan mode and doesn’t suggest any channel system, will it still work? Or is there a chance of interference?

For example, today while testing the flash, during the first scan it showed channel 20, but in the second scan, channel 20 was not shown—even though it was in almost the same place and time. So it seems the available channels can change.

 

[tugwilson]

Now, regarding the V1 as a commander:
Do I have to keep the screen on the Group view (showing groups A, B, C, D, etc.) in order for it to trigger the TT685 as a slave? I noticed that when I switch the V1 to the main TTL screen—where I can adjust flash exposure compensation—the slave TT685 doesn't fire.

So, is this the correct workflow?

1. First, go to the main TTL screen on the V1 and set the flash exposure compensation (e.g., -1).
2. Then switch back to the Group screen to trigger the slave TT685 (which I’ve assigned to Group A).

Is this how it's supposed to work? I originally thought I could stay on the main TTL screen, adjust exposure compensation easily, and still trigger the slave flash, but it seems that’s not the case.

There is no "main TTL screen". There are three screen each is displayed when the V1 is in one of three modes.

Stand alone mode: This is what you call "main TTL screen". In this mode the radio is off and the V1 acts as a normal speedlight.

Tx mode: In this mode the V1 acts as a radio transmitter and can change its own settings and remote lights in various channels.

Rx mode: In this mode the V1 is off the camera and its settings are controlled from a trigger ot a speedlight in Tx mode.

So when you switch from Tx mode ("Group screen") to Stand alone mode ("main TTL screen") it will stop triggering remote devices.

 

[fotowbert]

If I understand correctly, each TTL slave flash can independently adjust its own power to achieve the correct exposure, but they also work together to ensure accurate overall exposure for the entire image.

In general terms that is how TTL auto flash exposure is supposed to work. Let me restate it more precisely.

Each TTL flash group is assigned a unique power level by the in-camera Nikon TTL system such that the actual image capture has the desired exposure when all groups fire together.

Just exactly how it does this magic is unknown. It is unclear to me how Nikon's multiple group TTL will handle the more common lighting situation that you have. With a symmetric arrangement of identical speedlights with each group lighting the entire subject I observed the system made each group equal contributors to the final exposure. That's probably not what you want for a rim light group. Manual power rim light would be my recommendation.

• John

--
"[If you don't sweat the details] the magic doesn't work." Brooks, F. P., The Mythical Man-Month, Addison-Wesley, 1975, page 8.

 

[A_SCY]

If I understand correctly, each TTL slave flash can independently adjust its own power to achieve the correct exposure, but they also work together to ensure accurate overall exposure for the entire image.

In general terms that is how TTL auto flash exposure is supposed to work. Let me restate it more precisely.

Each TTL flash group is assigned a unique power level by the in-camera Nikon TTL system such that the actual image capture has the desired exposure when all groups fire together.

Just exactly how it does this magic is unknown. It is unclear to me how Nikon's multiple group TTL will handle the more common lighting situation that you have. With a symmetric arrangement of identical speedlights with each group lighting the entire subject I observed the system made each group equal contributors to the final exposure. That's probably not what you want for a rim light group. Manual power rim light would be my recommendation.

• John

Thank you

Another thing I noticed: when I tested the V1 flash on-camera in TTL mode, but in the Group screen - but i let the slave flash turned off, the exposure was noticeably lower compared to when I tested the same flash in TTL mode using the standard screen (not in Group mode and without triggering the slave flash). This suggests that the main flash exposure is being influenced by the rim light flash setup, which is not what I want. Ideally, I want the main flash exposure to remain independent of the rim flash. So for any reason the Rim flash will fault or something will affect my main flash exposure - as this main flash stay on the group screen .

 

[A_SCY]

If I understand correctly, each TTL slave flash can independently adjust its own power to achieve the correct exposure, but they also work together to ensure accurate overall exposure for the entire image.

In general terms that is how TTL auto flash exposure is supposed to work. Let me restate it more precisely.

Each TTL flash group is assigned a unique power level by the in-camera Nikon TTL system such that the actual image capture has the desired exposure when all groups fire together.

Just exactly how it does this magic is unknown. It is unclear to me how Nikon's multiple group TTL will handle the more common lighting situation that you have. With a symmetric arrangement of identical speedlights with each group lighting the entire subject I observed the system made each group equal contributors to the final exposure. That's probably not what you want for a rim light group. Manual power rim light would be my recommendation.

• John

 

[A_SCY]

Now, regarding the V1 as a commander:
Do I have to keep the screen on the Group view (showing groups A, B, C, D, etc.) in order for it to trigger the TT685 as a slave? I noticed that when I switch the V1 to the main TTL screen—where I can adjust flash exposure compensation—the slave TT685 doesn't fire.

So, is this the correct workflow?

1. First, go to the main TTL screen on the V1 and set the flash exposure compensation (e.g., -1).
2. Then switch back to the Group screen to trigger the slave TT685 (which I’ve assigned to Group A).

Is this how it's supposed to work? I originally thought I could stay on the main TTL screen, adjust exposure compensation easily, and still trigger the slave flash, but it seems that’s not the case.

There is no "main TTL screen". There are three screen each is displayed when the V1 is in one of three modes.

Stand alone mode: This is what you call "main TTL screen". In this mode the radio is off and the V1 acts as a normal speedlight.

Tx mode: In this mode the V1 acts as a radio transmitter and can change its own settings and remote lights in various channels.

Rx mode: In this mode the V1 is off the camera and its settings are controlled from a trigger ot a speedlight in Tx mode.

So when you switch from Tx mode ("Group screen") to Stand alone mode ("main TTL screen") it will stop triggering remote devices.

hank you for the explanation. It seems that using the Godox TT685 as an off-camera rim light in TTL mode is not ideal or reliable. The main issue lies in how TTL works across multiple flashes in a wireless setup.

When the Godox V1 is used as the on-camera master and the TT685 is acting as a slave (off-camera), TTL calculates the overall exposure by considering the light output of both flashes combined. This means that the V1 is no longer treated strictly as the main light — instead, the system averages or balances exposure based on what it "sees" from both units.

As a result, even if the TT685 is positioned behind the subject or aimed away (as a rim or kicker light), its contribution to the pre-flash metering will still influence the exposure calculation. This can confuse the TTL system and cause the V1 — which should be your main key or fill light — to fire at lower power, resulting in underexposed images.

In short, the TTL system doesn't understand the creative intent behind your lighting placement. It just sees two flashes and tries to balance them, even if one is meant to provide subtle rim lighting. For more consistent and predictable results in such setups, it's usually better to switch to manual power control for both flashes — especially for rim or background lights.

 

[tugwilson]

Thank you for your answer.
If I understand correctly, each TTL slave flash can independently adjust its own power to achieve the correct exposure, but they also work together to ensure accurate overall exposure for the entire image.

The flashes don't decide anything. The camera decides the power for each group and tells all the devices in each group what power to fire at. Generally you will have one device in each group but there can be an arbitrary number of devices in a group.

 

[A_SCY]

Thank you for your answer.
If I understand correctly, each TTL slave flash can independently adjust its own power to achieve the correct exposure, but they also work together to ensure accurate overall exposure for the entire image.

The flashes don't decide anything. The camera decides the power for each group and tells all the devices in each group what power to fire at. Generally you will have one device in each group but there can be an arbitrary number of devices in a group.

So, ultimately, the most effective approach is to use the slave TT685 flash as a rim light in manual mode. I plan to set it to a low power, around 1/64, and position it a few meters behind and slightly to the left of the main scene. Additionally, I’ll angle the flash away from me and my camera to prevent any direct light from hitting the lens and causing flare. I will take a few test shots on site and see how it works in practice.

What are your thoughts on this setup?