I'm trying to understand better how to control multiple flashes with TTL. I have the Sony A7Rv and use Godox flashes. Manual control seems straight forward, but sometimes I need results fast without test shots.
In the camera you can set:
1. Exposure compensation
2. Flash compensation
3. Exp.comp.set = Ambient only or Ambient + Flash
4. Reg. Flash Shooting Set - Shutter speed range
5. Reg. Flash Shooting Set - Iso
On the flash trigger you can set flash compensation for each OFC.
A few questions
What settings do you typically use and why?
Do you use on camera flash compensation to balance ambient vs flash?
Do you use on trigger compensation to balance ratio between flashes.
Does it send a TTL flash for each flash individually to measure the effect of each flash, or just one TTL flash?
What if you have different flash power or modifiers do you need to adjust for that or is it automatic.
Do you use the Reg flash shooting Set -ISO to reduce iso beyond what you would normally use without flash?
Any resources specifically about multiple OCF with TTL on Godox?
Do you really want all the lights auto adjusting via TTL? Or just the main? How many lights are you using?
TTL is handy for test shots. The TCM feature lets you lock exposure if you like what TTL gives you. Usually I take a TTL test shot, use TCM to lock as M exposure, tweak the background lights +/- from the trigger, then maybe set the main light group back to TTL if the subject or I are moving around.
TTL accounts for any modifiers you're using because the light is measured from the pre-flash. You don't have to explicitly adjust for that yourself. However, some modifiers are going to severely limit what your lights' max output might be. A double-baffled softbox might force a low power light to pop at 100% just to get to your initial TTL exposure. If ambient brightens or a change in your framing tells TTL to increase exposure, your light has nowhere to go if it's already maxed out. The background lights might be able to auto increase with TTL if they were only popping at 1/2 power in your initial tests. Now your group exposuyre is going to be out of whack because some lights are increasing output while other are already maxed out and can't go up. So often you're better off working in M so you can clearly see how close you are to your lights' limits.
Using massively overpowered lights seems like the only safe way to work in TTL. That way you can be more confident you're not inadvertently getting different lighting ratios while TTL is making changes for you.
jeffbuzz wrote:
Do you really want all the lights auto adjusting via TTL? Or just the main? How many lights are you using?
TTL is handy for test shots. The TCM feature lets you lock exposure if you like what TTL gives you. Usually I take a TTL test shot, use TCM to lock as M exposure, tweak the background lights +/- from the trigger, then maybe set the main light group back to TTL if the subject or I are moving around.
TTL accounts for any modifiers you're using because the light is measured from the pre-flash. You don't have to explicitly adjust for that yourself. However, some modifiers are going to severely limit what your lights' max output might be. A double-baffled softbox might force a low power light to pop at 100% just to get to your initial TTL exposure. If ambient brightens or a change in your framing tells TTL to increase exposure, your light has nowhere to go if it's already maxed out. The background lights might be able to auto increase with TTL if they were only popping at 1/2 power in your initial tests. Now your group exposuyre is going to be out of whack because some lights are increasing output while other are already maxed out and can't go up. So often you're better off working in M so you can clearly see how close you are to your lights' limits.
Using massively overpowered lights seems like the only safe way to work in TTL. That way you can be more confident you're not inadvertently getting different lighting ratios while TTL is making changes for you. ...Show more →
Thanks for the reply. I'm just getting started thinking about TTL with OCF. In the past the setup was static enough that I can do a few test shots, usually one light at a time, then combine everything on manual and good to go. I think if I have a good understanding of how TTL with multiple flashes works, then I can adapt a strategy to use it effectively.
I currently have 3 lights: 2 AD200, 1 TT685.
It certainly sounds reasonable to have the main light TTL and the others lower on manual. My main concern is not inadvertently overdoing flash if the subject wanders closer to a flash. I certainly understand the point of needing to know where you are operating with TTL to know if you are near the limits of the strobes, or also to make sure you have fast enough cycle at critical times. TCM sounds like the right choice for that.
The best source I’ve seen for using multiple TTL flash is material from Joe McNally. I THINK he moved to Profoto, but look at his older material on the web and in books. His educational and BTS material is very well regarded.
He is/was a Nikon user, but the principles are the same. He was ‘infamous’ (?) for using boatloads of Nikon speedlights for shoots. This was in the day when large lights/triggers did not enable TTL. Lots of web material, books, etc.
Conner999 wrote:
The best source I’ve seen for using multiple TTL flash is material from Joe McNally. I THINK he moved to Profoto, but look at his older material on the web and in books. His educational and BTS material is very well regarded.
He is/was a Nikon user, but the principles are the same. He was ‘infamous’ (?) for using boatloads of Nikon speedlights for shoots. This was in the day when large lights/triggers did not enable TTL. Lots of web material, books, etc.
Yes, Joe has been using Profoto for many years. He’s still a Nikon Ambassador and use to carry up to 16 Nikon SB-type flashes in a large Pelican travel case. A lot of the background lights were set manually and adjusted by looking at test shots. Usually they were accent lights, gelled lights, etc. I know of one occasion where he used approximately 23 various lights combining large Profotos and Nikon SB-910s for a single image. He would typically build up the image light by light.
What settings do you typically use and why?
***On an A75V - normal is 1/250 and Iso 100 - manual exposure. I use Hi Speed Sync only when required and very infrequently. Manual flash setting are optimal but TTL is indispensable in run and gun situations
Do you use on camera flash compensation to balance ambient vs flash?
***No - I shoot in Manual Exposure and set the ambient exposure first and then turn on my flash afterwards.
Do you use on trigger compensation to balance ratio between flashes.
***Yes - always
Does it send a TTL flash for each flash individually to measure the effect of each flash, or just one TTL flash?
*** I believe individually
What if you have different flash power or modifiers do you need to adjust for that or is it automatic.
**** Automatic
Do you use the Reg flash shooting Set -ISO to reduce iso beyond what you would normally use without flash?
*** Not sure what you are asking. I set Iso for the scene without flash and add flash after that. I do sometimes alter my shutter speed below 250 if I want more ambient in the final image.
Any resources specifically about multiple OCF with TTL on Godox?
Like others have recommended, I think if you're using multiple flashes, you should only have 1 of them at most on TTL and have the rest on manual. Honestly you'd probably take less time learning how to do everything in manual than try to figure out how to do a multiple TTL metering with strobes.
You could consider getting a light meter for indoors work and using a meter to set your ratios. Sekonic 858DU has optional radio module to control godox lights. Other than that would shoot in manual and then add lights after getting my ambient to pitch black in camera first
