Setting up dual Strobes TTL v TTL + Manual

[Ardy]

HI All, I was just setting up my camera for a trip to Bali next week and stumbled on something that i thought some of you may have some ideas about.

I was testing TTL with my Olympus OMD-EM5 with dual SnS flashes (DS-1 and YS110a). The TTL didn't come out too great with the flash set to fill mode. So I set the main flash to TTL and the 110a to manual and adjusted the output. I found that the coverage of the flash was very good. I tried it on a couple of images within my range which is mainly macro and still got good results.

Anybody else been stupid enough to test this out? Why is it working OK?

Also why was the TTL underexposing using both flashes?

---------- Post added August 12th, 2015 at 10:26 PM ----------

PS I mostly use Manual settings for my photography but I was just farting around seeing what difference it would make!

 

[smoore]

I am not sure I understood what you did. You mention the flash settings but not the setting for the flash on the camera. If you had the camera flash set to manual (that is using one of the reduced output levels like 1/4 or 1/64th), then there would be no pre-flash from the camera and I suspect that the two flashes set to TTL might fire late and this would result in dark pictures. If you then set one of the flashes to manual mode it would fire (without any pre-flash) properly synched to the camera's flash and your pictures would look fine. I suspect that the flash set to TTL would fire late so that your pictures are lit by only one properly synched flash. If I am having exposure problems one way to make sure your camera and flashes are in synch is too shoot pictures into a mirror. If the picture does not have the flashes lit, then you have a synch problem. Since you indicate you mostly shoot manual I would not be surprised if you had the camera slash set to manual. The one thing that throws me is the reference to fill mode which applies to the camera flash rather than the strobes. If the camera flash was set to fill (which is the proper setting for TTL with the strobes), then I am not sure what is going on. I use Inon strobes so I cannot comment on whether the problem is with a settings on your two strobes.

 

[Ardy]

I am not sure I understood what you did. You mention the flash settings but not the setting for the flash on the camera. If you had the camera flash set to manual (that is using one of the reduced output levels like 1/4 or 1/64th), then there would be no pre-flash from the camera and I suspect that the two flashes set to TTL might fire late and this would result in dark pictures. If you then set one of the flashes to manual mode it would fire (without any pre-flash) properly synched to the camera's flash and your pictures would look fine. I suspect that the flash set to TTL would fire late so that your pictures are lit by only one properly synched flash. If I am having exposure problems one way to make sure your camera and flashes are in synch is too shoot pictures into a mirror. If the picture does not have the flashes lit, then you have a synch problem. Since you indicate you mostly shoot manual I would not be surprised if you had the camera slash set to manual. The one thing that throws me is the reference to fill mode which applies to the camera flash rather than the strobes. If the camera flash was set to fill (which is the proper setting for TTL with the strobes), then I am not sure what is going on. I use Inon strobes so I cannot comment on whether the problem is with a settings on your two strobes.

Thanks for this. I don't have a problem I am just trying to understand what is going on.

I will explain a little clearer.

1. I set the camera flash to fill mode
2. I set both flashes to TTL (not great results a little underexposed)
3.Changed the 110a to manual 2 which is the normal manual setting - camera still in fill mode.
4. Took several pictures slowly increasing 110a output until shot is exposed correctly. The DS1 is still in TTL.
5. Took shots up to 1m away and appears to expose properly.

I will use manual flash and 1/64th manual camera flash on this trip as I normally do.
I just want to understand what is going on and why it would work, in case it offers a better way of dealing with TTL.

Hope that makes sense.

 

[bvanant]

What happens when you use just one flash. I suspect that you might be getting underexposure (depending on f:stop and shutter speed) from either strobe. In my hands at least the EM-5 underexposes in TTL (try shooting the same scene without the housing and see. I am not surprised that the 110a works in manual if the setting is to ignore pre-flash.
Bill

 

[smoore]

What happens when you use just one flash. I suspect that you might be getting underexposure (depending on f:stop and shutter speed) from either strobe. In my hands at least the EM-5 underexposes in TTL (try shooting the same scene without the housing and see. I am not surprised that the 110a works in manual if the setting is to ignore pre-flash.
Bill

Bvanant if the camera flash is set to fill wouldn't you expect it to fire pre-flashes which should set off the 110 (set to manual) prematurely? I still find firing the setup into a mirror is the quickest way to figure out if one or both of my flashes are properly synched with the camera's flash. I usually do this in my hotel room in both TTL and manual just to make sure everything is working. I cannot figure out what is causing Ardy's underexposure unless it is that the camera tends to underexpose in TTL or as you also suggested he us using a combination of f stop and aperture that will not expose correctly in TTL. The former seems more likely as wrong settings should also lead to underexposure in manual. If that is the case, and the flashes are properly synched with the camera for TTL, I suspect that increasing flash compensation in the camera might fix the problem. I use Inon strobes so when I shoot TTL I use the TTL compensation on the strobes instead of the flash compensation in the camera.

Ardy please let us know if you figure this out.

 

[Interceptor121]

TTL under exposing may simply mean TTL is not actually working and is being triggered by red eye pre flash for example. To eliminate the problem set the camera to no red eye and TTL flash and the strobes to manual pre flash on and see if they fire properly. If they do put TTL on the strobes and then figure out one strobe at time if exposure works. If TTL works on one but not the other it doesn't make sense to shoot one in TTL and the other in manual as the strobe in TTL will try to compensate for the other one you may want to shoot manual to have full control

 

[bvanant]

I am not sure about the 110a flash, but I was under the perhaps mistaken impression that you could have it ignore the first pre-flash. Of course you are right, in fill mode the camera does indeed make a pre flash which works fine on the D1. I will have to play with the redeye switch to see if that is what was causing me to think TTL in the camera was wonky.

Bill

 

[Ardy]

Hi Guys thanks for the replies. I have checked it and both fire at the same time with one on manual and one on TTL with camera set to fill.

If I am feeling really stupid one day I might give it a go underwater BUT! as I have a list of things I want to shoot longer than my arm, and more difficult to find than Hannibal's way over the Alps. I may not get round to it.

At the moment the sea is up in Tulamben so I may find myself messing around somewhere in which case I will give it a go.

 

[bvanant]

Good luck with the waves, we were shut out a couple of days at Villa Markisa; too big waves to get to the boats.
Bill

 

[Larry C]

I don't shoot an Oly so I'm not sure about the settings, but I would think that if you're setting the camera on fill, it would give you a lower output flash than the ambient light. Shooting the other strobe at a brighter manual setting may be allowing the camera to set the ttl "fill" flash for shadowed areas giving you nice overall lighting. If I'm totally off base, ignore me.