1

I've never used a TTL flash before and have used my manual flash in three shooting sessions so far. I will receive my first TTL flash (Nikon SB910) and was wondering the following things:

  1. In a wedding, with on-camera flash, bouncing off the ceiling, walking around taking pics of people dancing, etc. Does a TTL flash have advantages, and if so, what?

  2. In a park, a model sitting on a bench, flash off-camera with light stand and umbrella, what are the advantages of TTL flash, if any?

  3. As far as I understand, my PocketWizard Plus III isn't TTL-capable, so the SB910 will act in manual mode. But on YouTube videos I've seen that you can use the built-in camera flash as commander and trigger an off-camera TTL flash and they will "talk TTL"? Is this correct?

If it matters, my camera is a Nikon D810

3

In a wedding, with on-camera flash, bouncing off the ceiling, walking around taking pics of people dancing, etc. Does a TTL flash have advantages, and if so, what?

The main advantage is speed. Given that event shooting is mostly about anticipating moments at the event, and the nature of events being that you usually only get one chance at capturing any particular moment (first dance, cake cutting, exchange of rings, etc.) timing is everything, and having to wait that half a second to dial from 1/2 to 1/16 power might be enough to get you to miss the shot.

When you are walking around and moving, the lighting conditions of your subjects will continually be changing. Which also means that you will probably need to reset the power level of the flash for each shot. Throwing bouncing into the mix may make guesstimating the proper power level you need a bit harder, because you have to calculate the distance to and from the bounce surface, rather than directly from the flash to the subject. iTTL can take care of that for you--at least well enough to get you in the ballpark.

Think of it like using A mode on the camera vs. M mode on the camera. The flash power, like the shutter speed in A mode, is set based on camera metering. The camera tells the flash to send out a small "preflash" burst of light; meters it, and then based on the reading of the meter, adjusts the flash's output accordingly to get the exposure to where the camera's auto-exposure system thinks it should be. It's faster, but will be more inconsistent (since the metering will always change, and with predominantly light or dark scenes, may not get you exactly where you want to go). You may still have to ride the flash exposure compensation, but you will at least be somewhere in the ballpark. With manual, you'll have to think a lot faster and adjust all the time.

In a park, a model sitting on a bench, flash off-camera with light stand and umbrella, what are the advantages of TTL flash, if any?

The main advantages are that, if you can use TTL radio triggers or CLS, you could also have access to remote power control from the camera (i.e., you don't have to keep walking up to the flash to adjust the power level), and you'll have access to FP/HSS flash, so you can use shallow depth of field in the daytime (much harder to do when you're stuck at 1/250s or slower shutter speeds in sunny-16 conditions; ND filters are the other way to get around this).

See also: an old Strobist post on the introduction of the Radiopopper triggers. There are, of course, many TTL-capable triggers from a variety of manufacturers these days.

... on YouTube videos I've seen that you can use the built-in camera flash as commander and trigger an off-camera TTL flash and they will "talk TTL"? Is this correct?... If it matters, my camera is a Nikon D-810

Yes, you can do this with your D810 and SB910 without any additional equipment. However, CLS is an optical triggering system, and requires that the sensor panel on the side of the flash be able to "see" the commander signal from the D810's pop-up flash. Think of it like a tv remote. It works very well indoors in lower light conditions with bounce surfaces around, but outside on location, in bright sunlight, the system can become less reliable, with a smaller range, and more stringent line-of-sight requirements. Remember, your pop-up flash can't swivel, so it's not like you can put your off-camera flash behind you or to the side of the camera.

In addition, I don't think any of the Nikon pop-up flashes can do FP/HSS, so they can't communicate wireless FP/HSS.

  • excellent answer :) I was able to fire the SB910 remotely from CLS mode of Camera ( Nikon D-810) but it wasn't reading the zoom from the camera lens , it was reading it when I installed it on the camera but not when it was off camera, it was only just firing...but no zoom reading from lens...Is that normal in this mode? or something I did wrong? Thanks. – Brandon May 15 '15 at 4:46
1

Which flash helps? and in what areas does it help?

I'm sure you're familiar with the difference between automatic exposure modes (e.g. Program) and manual mode on your camera. The difference between TTL and manual flash is similar. With TTL, the camera measures the exposure from the flash and the scene and adjusts the flash power to create a reasonable exposure. That's great when you want to take photos of things, people, etc. and have them turn out with about the right amount of light in the scene. And you still have control over a lot of how the image looks because you can the flash in different directions, bounce it off any available surface, etc. Once you get a feel for how the camera adjusts the flash power, you can use other camera parameters (shutter speed, aperture) to control the amount of ambient light.

But just as you use your camera's manual mode when you want a result that's different from what you get with auto exposure, manual flash is useful when you're trying to achieve a specific effect. With manual, you control everything yourself -- that's more work, but also a lot more control.

As far as I understood, if I use my PocketWizard Plus III they can't transfer TTL info so even that TTL flash will act in Manual mode.

That's true, but there are radio triggers that do support TTL, including some from PocketWizard.

But on YouTube videos I saw that looks like we can use the built in camera flash as commander and trigger for the Off Camera TTL flash and they will talk TTL?

Yes, they can use TTL. Here's a link to a tutorial on using your on-camera strobe to control off camera units using TTL.

See also the section on Commander Mode starting on page 334 of the D810 manual (PDF).

  • I didn't think it was correct that using on-camera flash as a master to trigger a slave flash was TTL compatible? – laurencemadill May 13 '15 at 15:19
  • Thanks that clarified some confusions. So are we sure Built in flash can communicate TTL to that SB-910 when it is off camera? – user1899082 May 13 '15 at 17:22
  • 1
    @user1899082 In addition to the linked tutorial explicitly showing how to set up the on-camera flash to control two groups of remote flashes with TTL, there's also a lot of evidence in the manual for the D810. Check page 430, for example, which has a matrix that shows that the SB-910 can use TTL while being controlled via Advanced Wireless Lighting. See also the section on Commander Mode starting on page 334. – Caleb May 13 '15 at 17:43
  • 1
    @laurencemadill Canon has a very similar system, letting you use E-TTL II with optically triggered Canon Speedlites. Note that in both cases there's a lot more going on than a simple fire when you see a flash optical trigger -- there's a series of pre-flashes that transmit the necessary information to the remotes. – Caleb May 13 '15 at 17:48
  • 1
    You will, however, have more limits with your optical trigger. Bright sunlight, distance and line of sight are all limiting factors. – Robin May 13 '15 at 20:04
1

Flash (manual or TTL) exposure varies with subject distance (and ISO and aperture too, but also subject distance). Twice the distance is exposure two stops down. So as you walk around the room shooting pictures, or you are chasing kids running around, then many cases are surely DIFFERENT situations, different distances, etc.

With manual flash, you have to determine and set a proper flash level for each situation.

With TTL flash, it meters the preflash reflected from the subject, and adjusts accordingly (automatic point&shoot flash).

It is true that reflective meters (camera meters) vary what they read depending on the subjects colors. White walls or dresses reflect a lot of light, and read high. Dark colors (like black tuxedos) reflects poorly and read low. Photographers learn to deal with this, and they also judge the scene, and set flash compensation accordingly. That is one factor. But another is that as you walk around, and the distances vary, TTL does that well. Flash exposure is only correct at ONE distance from the flash. Metering it is a good thing. More at http://www.scantips.com/lights/flashbasics.html

Manual flash is better in fixed situations, like seated portraits or table top work, subjects that do not move around.

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.