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TTL-BL vs TTL

James C. Reed Sr. , Jan 10, 2007; 11:20 a.m.

I have a flip-it light reflector that I want to affix to my sb800 speedlight, which will be mounted onto a strobaframe connected by way of an SC-17 off camera sync cord, from my D70s camera. My question is what flash mode should I be using TTL-BL or standard TTL? and what is the reasoning for using one flash mode over the other?

Responses

Robert Gulotta , Jan 10, 2007; 12:36 p.m.

ttl bl is best used when the background is brighter than the subject... if you use ttl bl in general it seems to underexpose the subject. BL is 'balance' I think, and it tries to balance the foregrond with the background... if the background is dark, it lowers the output, and I think thats why it doesnt work well.. if the background is bright, I think it ups the output so you dont end up with underexposed subjects.

Eric Vichich - Tampa Bay, FL , Jan 10, 2007; 01:23 p.m.

typically, I have heard that it is best to use TTL-BL when using flash as fill (balancing flash and ambient). Like if you were outside and you just wanted to use a little flash to open up the shadows under the eye sockets. I know some who just leave it on TTL-BL all the time and they seem to think it works better.

Do some test shots both ways in different lighting situations and see what you like.

Robert Gulotta , Jan 10, 2007; 04:14 p.m.

I am not sure, but I think if you leave the flash in BL mode, the camera might factor that in the exposure metering if you are using an 'auto' mode on the camera (P, and perhaps A and S)... When I shoot flash, I almost always am in M mode, which may limit the effectiveness of the BL setting too. Just a thought

Michael Wildi , Jan 11, 2007; 08:27 a.m.

James, if you use your sb800 as the main light (e.g. the flash will be brithter than the ambient light) set it to TTL. This works with direct, bounce, flip-it, on- or offcamera flash etc. To prevent dark or black backgrounds, just open up the shutter speed. I use this setting for almost all indoor shots or night shots.

If you use your sb800 as a fill light (e.g. the flash will be lighter than the ambient light) set it to TTL-BL. This works best with the flashhead in the regular 90 degrees forward postition. If you tilt or rotate the flashhead the (invisible) preflashes won't go of and the flashexposure could be off. I use this setting outside in sunny days and in backlight situations.

Best,

Michael

Michael Wildi , Jan 11, 2007; 08:30 a.m.

"...e.g. the flash will be lighter than the ambient light..."

I mean the flash will be weaker than the ambi...

Sorry for bad English. My mother language is Swiss German.

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