Working Method Part II - TTL Flash

Following on the heels of my last working method post, here's the bigger badder version. Actually this one is smaller with less blah-blah preface. Consistency in working-method is the common theme here rather than a random bag of stuff that might work. Last time I chose to illustrate a potential homogenized auto-exposure working method for those that find exposure automation quicker or more convenient. It might not be exactly what suits your particular situation or your gear setup – take it as a starting point towards whatever might work for you, your subject matter, and your gear. I tend to prefer manual exposure for most of what circumstances I tend to shoot in. The ulterior motive for that particular method was how related it happens to be to Nikon's CLS/TTL flash control features.

I stumbled across two situations in the last few weeks where long-time Nikon shooters that use Nikon CLS and TTL exposure control were unaware of one of the systems best features. Well not exactly unaware but not really using it as designed. This one might be an epiphany for you – quite possibly earth shattering so hold onto your seat. Again if you're already working in the way I describe grab a bag of popcorn and you can commence with the head slapping and yelling "I can't believe there's people that don't know that". For non-Nikon shooters there's something here for you too. Possibly your camera system's flash control provides similar features or not… something for you to at least look into.

First up without regurgitating any huge how-to for Nikon CLS in terms of what buttons/modes/etc do what, CLS in a nutshell allows wireless control of off-camera flash behavior. I use CLS all the time because I'm lazy. Typically I use it in manual mode where I just dial flash power up or down from the camera instead of walking over to my remote flash and dialing it up or down from the speedlight itself. Doesn't really matter if I do it from camera or not – same results. You don't have to use CLS only for TTL, there's a bunch of options for how each flash group is controlled. Today I'll outline a working method that actually uses TTL. I use it that way sometimes, typically when I'm working really fast and only making a few shots of each various scene/setup/whatever vs really working the same setup for a longer period.

When using TTL here's how everything related is setup in my camera and speedlights:

  • I use manual exposure for ambient so my camera is on M. If there is a chance I happen to use AE even accidentally I have my custom settings dialed in to make exposure compensation affect only ambient vs ambient+ flash.
  • I setup my speedlights (usually only one or two) for TTL via the commander and put them on independent groups so that I can control their output independently if there's more than one.
  • Most of the time I'll use the built-in commander on the D600 (same goes for D800, D7000, etc – pretty much any semi-pro Nikon with built-in flash) I will set that flash to OFF. Sometime's I'll use the dedicated commander or an SB-800/900 as a commander if I need more than two independent groups or the built-in always pointed forward flash will expose even in the off position. Yes even when it's off a combination of super high ISO and large aperture will show exposure from the built-in when set to off. It fires at super low output at "off" to manufacture the IR control signals.

Okay we're all setup from a camera point of view now get ready for the epiphany (maybe). So what do we do? Take a test shot and then fiddle with setting compensation of plus or minus on each flash as well as ambient? We could but as usual variations in framing, subject position in the frame, proportion of background to foreground and a million other things can and will cause exposure changes frame to frame. If what you want is to make a series of shots with consistent exposure instead of potentially random variations of the same subject in the same scene you're going to want to do something prior to taking the first shot. Get ready for it… here it comes… hit the FV-LOCK BUTTON prior to doing anything. Usually this is default to the front fn-button.

Yep there's the secret. The use of the FV-Lock button isn't supposed to be used after you chimp a shot and make adjustments and look at them as I have seen quite a few photographers do. You use it before you start chimping and making adjustments to TTL compensation on the flash/s. So let's run through this working method that I happen to use when using TTL exposure control with speedlights.

  • Set ambient exposure starting point in manual exposure control based on my best guess and my intent. It's locked in because it's manual.
  • While my camera is still pointed at the subject/scene, hit the FV-Lock button to lock-in whatever the TTL system thinks is "right". No test frame shot yet…
  • Now shoot a test frame. Evaluate what's going on vs. what I want via a quick chimp…
  • Adjust ambient up or down in manual… typically via shutter speed (ISO, and aperture were chosen to suit my best guess at not working the flashes too hard based on the circumstances – that will come with experience so you may have to re-fiddle with that your first time out)
  • Dial in TTL compensation up or down by flash group based on best guess… again experience. Do this for a few sessions any you will be amazed at how good you get at what values to use and it also goes along way TTL or no TTL to adjusting light to your desires.
  • Shoot another confirmation shot to see if that's what you want or at least going in the right direction (This is usually just a confirmation with me at this point with no further adjustments required – you may need a couple of repeat/adjust cycles here while you're getting used to it)
  • Shoot shoot shoot shoot, shoot some more and have absolutely the same exact exposure and ratios frame to frame until you want a different setup.

The key here is that FV-lock locks in what the camera thinks without any exposure at all as long as it's pointing at the scene. FV-lock is not for chimping something, adjusting and then locking it in after you did that. It might lock in what you saw prior to engaging it, it might do something completely different based on a lot of factors. I outlined this using manual exposure for ambient. You could just as easily use auto exposure for ambient in combination with the AE-lock methodology I outlined last time. I don't, why bother… You may think differently.

Be aware of what things reset FV-lock. On Nikons it's the same things as AE-lock. If your flash system supports this make sure you understand all the little things like this as well as how other custom settings influence the behavior of flash control (auto-FP is one example, which I use but only on purpose which contributes to my manual ambient control preference of shutter, aperture, and ISO). Why do I choose TTL sometimes and manual in others… two different working methods? The shot at the top was one circumstance.

I was moving scene to scene very fast and only making a couple of exposures of each setup to get a feel for the potential of the space that I planned on using down the road for a workshop. I was bouncing the speedlight off unfamiliar surfaces in a space I've never shot flash in before and guessing a particular power level as a starting point would have taken a little more time and evaluation. I weighed that against the fact that there would be no point at which I was working a scene so long where my meter would time-out and FV-lock would go off. If you are working quickly and you can save time by not guessing your flash output starting point and you know that you are not going to turn the camera off or change speedlight batteries, or have a downtime long enough for the meter to timeout and reset the FV-lock and AE-lock than this is very reasonable. A different circumstance in a more static setup where all of those things might happen like after a few shots with the wind machine your stylist needs to adjust the subject's hair, or dress, or add a belt or whatever. In that more static circumstance you just want exactly the same thing to happen over and over in terms of exposure until you change it on purpose. That might be better using manual flash via CLS.

So how long did that working method take in reality for each scene I shot? 10-30 seconds at most. Usually more like 10 seconds with just ambient and a simple one or two speedlight setup.

RB

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