Why are my flashes inconsistent

[tstefoto]

I just purchased the Godox TT600's. These are manual off camera flashes. They have brand new alkaline batteries in them. While on a shoot, I had them dialed in to the settings I wanted. The first shot blew the scene completely out. I did not change the settings on anything, but took a second shot and it was perfect. Why does this happen? Why are they not consitant in the output power? I have posted the first and second shot below.

 

[tirediron]

Cant' see the images but the first thing that comes to mind is that either the camera or the flash was in an auto/semi-auto mode and the other was in manual or program.

 

[Derrel]

It's at least possible that the flash does not automatically "dump" excess capacitor stored energy when switching to lower power settings, and if shot #2 was perfect, at let's say 1/4 power, while shot #1 was blown out, this would likely be the case.

SEE ALSO; Operator Error, i.e.>>>>>

Cant' see the images but the first thing that comes to mind is that either the camera or the flash was in an auto/semi-auto mode and the other was in manual or program.

 

[JBPhotog]

Can't see the images but what are the camera settings? Were you using HSS?

 

[ronlane]

I'd tend to go with @tirediron or @Derrel's solutions.

 

[adamhiram]

I've seen slight variations in output power (less than 1/3 stop) when firing back to back, as fast as it will cycle, but nothing like that. Without any more information to go on, I'm leaning towards Derrel's explanation as well.

 

[Derrel]

https://www.amazon.com/Godox-Speedl...hvlocphy=&hvtargid=pla-4583863979986257&psc=1

Looks pretty good for the money...

 

[JBPhotog]

I suspect this unit, as most modern speed lights don't actually dump capacitor power when they are turned down. They simply restrict the current using a IGBT semiconductor so as you turn them down, the "left over" capacitor charge is used for the next discharge.

I noticed from the link Derrel kindly included that this unit can be triggered via a compatible TTL trigger which leads me to believe this is the nexus of the inconsistent flash. However, until the OP adds to the story, this is all conjecture on my part.

FWIW, in order to nail down the issue, one should set up the flash on a stand in manual mode, use a light meter and do multiple flashes at known settings and see if the speed light is inconsistent. If it is, then the unit is defective.

 

[zombiesniper]

It's at least possible that the flash does not automatically "dump" excess capacitor stored energy when switching to lower power settings, and if shot #2 was perfect, at let's say 1/4 power, while shot #1 was blown out, this would likely be the case.

I have the TT600 and this is the case for this flash.
I'm not saying this is the OP's problem but if you drop the flash power I always hit the test on my remote to dump the capacitor. If you don't you'll get the higher flash power.

 

[Dao]

I have this as well (2 flashes with remote trigger)
https://www.amazon.com/gp/product/B019MQE7R4/

And I'd not have any issue at all. Dial the flash settings on the trigger mount on the hot shoe, set the shutter speed, aperture and iso and shoot. It just works. As Tirediron and Derrel said, maybe some settings in the camera some how set to auto (i.e. auto iso)

 

[tstefoto]

It's at least possible that the flash does not automatically "dump" excess capacitor stored energy when switching to lower power settings, and if shot #2 was perfect, at let's say 1/4 power, while shot #1 was blown out, this would likely be the case.

SEE ALSO; Operator Error, i.e.>>>>>

Cant' see the images but the first thing that comes to mind is that either the camera or the flash was in an auto/semi-auto mode and the other was in manual or program.

It's at least possible that the flash does not automatically "dump" excess capacitor stored energy when switching to lower power settings, and if shot #2 was perfect, at let's say 1/4 power, while shot #1 was blown out, this would likely be the case.

I have the TT600 and this is the case for this flash.
I'm not saying this is the OP's problem but if you drop the flash power I always hit the test on my remote to dump the capacitor. If you don't you'll get the higher flash power.

Thank you for that! I will try that!

 

[WayneF]

I suspect this unit, as most modern speed lights don't actually dump capacitor power when they are turned down. They simply restrict the current using a IGBT semiconductor so as you turn them down, the "left over" capacitor charge is used for the next discharge.

FWIW, I strongly agree. Any speedlight does not "dump" like studio flash can do. They always fully charge the capacitor to 100% (which is why we wait for recycle to complete), and then flash power level is determined by duration to quench it off as necessary. Duration would normally have no fixed meaning if it does not always start at 100% voltage. So a too-fast repetition rate not allowing for recycle completion can be a problem, but doesn't sound like that this time.

Rather than a gross inconsistency, my guess is the situation is simpler. For example, if Auto ISO was on, a Manual flash cannot react to ISO changes. Cameras can probably communicate with their dedicated flashes to know they are present and Manual, to prevent Auto ISO from changing, but a dumber flash would be at risk of suffering from Auto ISO.
This one says "Compatible for Canon,Nikon,Pentax,Olympus and and Other Digital Cameras" and does NOT do TTL, which does NOT sound like a dedicated flash with camera communication. Therefore, one good guess would be Auto ISO issues. Turn Auto ISO off for use with a Manual flash. This is Not optional with a Manual flash (exceptions for dedicated flash).

Likewise, any camera automation mode that can change aperture will screw up a Manual flash, because it cannot react to changes. Manual must use the power level we set, regardless how we might make other changes. Also set camera Manual mode with a Manual flash. This is Not optional with a Manual flash (camera A mode with fixed aperture could be an exception).

Regardless, a Manual flash is NOT auto exposure, and we absolutely MUST set power level and aperture and ISO properly and manually for any picture. There was no discussion how that was done, but again, it is Not optional.

Much more detail (for example, reported ISO and aperture, etc) needs to be known about both situations to have much clue. The Exif data will show all this. If ISO or aperture are not the same in both, that is the issue. If both subject situations were not the same, then also detail about distance and power level, and bounce or direct, etc, etc.

 

[JBPhotog]

I suspect this unit, as most modern speed lights don't actually dump capacitor power when they are turned down. They simply restrict the current using a IGBT semiconductor so as you turn them down, the "left over" capacitor charge is used for the next discharge.

FWIW, I strongly agree. Any speedlight does not "dump" like studio flash can do. They always fully charge the capacitor to 100% (which is why we wait for recycle to complete), and then flash power level is determined by duration to quench it off as necessary. Duration would normally have no fixed meaning if it does not always start at 100% voltage. So a too-fast repetition rate not allowing for recycle completion can be a problem, but doesn't sound like that this time.

Rather than a gross inconsistency, my guess is the situation is simpler. For example, if Auto ISO was on, a Manual flash cannot react to ISO changes. Cameras can probably communicate with their dedicated flashes to know they are present and Manual, to prevent Auto ISO from changing, but a dumber flash would be at risk of suffering from Auto ISO.
This one says "Compatible for Canon,Nikon,Pentax,Olympus and and Other Digital Cameras" and does NOT do TTL, which does NOT sound like a dedicated flash with camera communication. Therefore, one good guess would be Auto ISO issues. Turn Auto ISO off for use with a Manual flash. This is Not optional with a Manual flash (exceptions for dedicated flash).

Likewise, any camera automation mode that can change aperture will screw up a Manual flash, because it cannot react to changes. Manual must use the power level we set, regardless how we might make other changes. Also set camera Manual mode with a Manual flash. This is Not optional with a Manual flash (camera A mode with fixed aperture could be an exception).

Regardless, a Manual flash is NOT auto exposure, and we absolutely MUST set power level and aperture and ISO properly and manually for any picture. There was no discussion how that was done, but again, it is Not optional.

Much more detail (for example, reported ISO and aperture, etc) needs to be known about both situations to have much clue. The Exif data will show all this. If ISO or aperture are not the same in both, that is the issue. If both subject situations were not the same, then also detail about distance and power level, and bounce or direct, etc, etc.

Agreed Wayne. Precisely why I asked for camera settings that so far the OP has not provided.

 

[Derrel]

I suspect this unit, as most modern speed lights don't actually dump capacitor power when they are turned down. They simply restrict the current using a IGBT semiconductor so as you turn them down, the "left over" capacitor charge is used for the next discharge.

FWIW, I strongly agree. Any speedlight does not "dump" like studio flash can do. They always fully charge the capacitor to 100% (which is why we wait for recycle to complete), and then flash power level is determined by duration to quench it off as necessary. Duration would normally have no fixed meaning if it does not always start at 100% voltage. So a too-fast repetition rate not allowing for recycle completion can be a problem, but doesn't sound like that this time.

Rather than a gross inconsistency, my guess is the situation is simpler. For example, if Auto ISO was on, a Manual flash cannot react to ISO changes. Cameras can probably communicate with their dedicated flashes to know they are present and Manual, to prevent Auto ISO from changing, but a dumber flash would be at risk of suffering from Auto ISO.
This one says "Compatible for Canon,Nikon,Pentax,Olympus and and Other Digital Cameras" and does NOT do TTL, which does NOT sound like a dedicated flash with camera communication. Therefore, one good guess would be Auto ISO issues. Turn Auto ISO off for use with a Manual flash. This is Not optional with a Manual flash (exceptions for dedicated flash).

Likewise, any camera automation mode that can change aperture will screw up a Manual flash, because it cannot react to changes. Manual must use the power level we set, regardless how we might make other changes. Also set camera Manual mode with a Manual flash. This is Not optional with a Manual flash (camera A mode with fixed aperture could be an exception).

Regardless, a Manual flash is NOT auto exposure, and we absolutely MUST set power level and aperture and ISO properly and manually for any picture. There was no discussion how that was done, but again, it is Not optional.

Much more detail (for example, reported ISO and aperture, etc) needs to be known about both situations to have much clue. The Exif data will show all this. If ISO or aperture are not the same in both, that is the issue. If both subject situations were not the same, then also detail about distance and power level, and bounce or direct, etc, etc.

Agreed Wayne. Precisely why I asked for camera settings that so far the OP has not provided.

We might never know!