Off Camera TTL Question
/forum/topic/1129249/0



Image1
Registered: Feb 27, 2005
Total Posts: 192
Country: United States

Not being heavily experienced with TTL I am wondering if this can be accomplished, I would like to use my speedlite on a long TTL cord with an Umbrella as my main, and then also use the cameras Popup flash ajusted to a lower power setting for fill, does this seem feasible or will there be exposure problems using these two speedlights together on TTL?

Thanks John



cgardner
Registered: Nov 18, 2002
Total Posts: 9376
Country: United States

The first problem with your proposed idea is getting the pop-up flash up to function with the TTL cord attached to the hot shoe. Is that even physically possible with your camera? What camera brand and model? What brand/model flash?

With some Nikon and Canon bodies the built-in flash can act as wireless Master and also provide metered TTL fill, but in terms of controlling the ratio effectively at normal shooting ranges with TTL ratios I would suggest it would be better to use two equal powered flashes for maximum range and control. I describe how I use a pair of 580ex flashes here: http://photo.nova.org/CanonPracticalUsage/

But if using long TTL cord and umbrella on flash as your key light you'll wind up bouncing a lot of spilled fill around a small room and should be able to get by with a reflector as fill. Also while you might use the TTL cord to connect the flash you'll get more consistent exposures by using the flash in manual mode. TTL exposure control is better suited for "run and gun" type shooting where subject-flash distance changes shot-to-shot.



BrianO
Registered: Aug 21, 2008
Total Posts: 8454
Country: United States

Image1 wrote: ...I would like to use my speedlite on a long TTL cord with an Umbrella as my main, and then also use the cameras Popup flash ajusted to a lower power setting for fill, does this seem feasible or will there be exposure problems using these two speedlights together on TTL?

Exposure problems wouldn't be an issue; I often use the pop-up on my 7D along with one or more Speedlites, and I can use either Manual or ETTL Autoflash and set the ratios as I want.

The problem is that with most cameras you can't use the pop-up and the hot shoe at the same time. Your Olympus may be an exception, but I don't know.

When I'm using the pop-up on my 7D with Speedlite(s), it's set as the Master in a wireless setup.



williamkazak
Registered: Jun 08, 2006
Total Posts: 6140
Country: United States

That is why I use Pocket Wizards, now. I can use a speedlight or two on stands, each with a PW, and put one PW in my Nikon camera shoe.



Image1
Registered: Feb 27, 2005
Total Posts: 192
Country: United States

I can use my popup and also hook into the hotshoe, so I guess it's possible to use it and a speedlight on a TTL Cord, one other question how would I ajust the ratio of the lighting, I would like to do maybe a 4 to 1 by knocking down the popups intensity thru the camera, is that usually possible? or do I have to physically diffuse it down 2 stops somehow.



BrianO
Registered: Aug 21, 2008
Total Posts: 8454
Country: United States

Image1 wrote: ...I would like to do maybe a 4 to 1 by knocking down the popups intensity thru the camera, is that usually possible? or do I have to physically diffuse it down 2 stops somehow.

"Usually" it's possible and simple: you set the pop-up as Master, and the remote as Slave on Channel B. You then set the A:B ratio to whatever you like, and the camera -- if in ETTL mode -- will send out metering pre-flashes, set each flash to the correct exposure, and trigger them in sync. You can also set the flashes to Manual mode, and set the power output of each seperately.

That's the usual way; with both a pop-up and a hot-shoe flash at the same time (which I didn't think was possible) I don't know how you'd do it. The camera has to know which flash is which.



Image1
Registered: Feb 27, 2005
Total Posts: 192
Country: United States

Thanks To everybody for their help I will have to try out these Methods. ...John