Monday, February 18, 2013

How To: Easily Fine Tune Your Flash Right From the Camera



Strobist reader (and relative lighting newb) Ron Ibarra of New York City asks, via Twitter:

"I can't control the flash through the PC cord. Am I doing something wrong?"

Nope, Ron, you are not. A PC cord is what we call a "dumb sync," meaning it only triggers the flash but does not otherwise control it. And if you are a smart photographer, all you really need is a dumb sync.

That's because you can control everything right from the camera itself. And today's follow-the-bouncing-ball post will show you the super-easy way to do just that.
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Shown at top is The Spear Center in downtown Columbia, MD. For many years it has served as the main gathering space for local social events. I photographed it for a piece on Columbia's iconic buildings in transition.

In shooting it, I wanted to call some attention to the beautiful, "vertical" wood ceiling which is its main design element. So I lit it with a couple of speedlights.

And the process for this shot serves as a good example of easily controlling both your flashes and the ambient from your camera with a dumb sync. (In this case I was using an IR remote, which is a manual-only—i.e., "dumb"—sync.)

Normally, controlling flash from camera is a two-step exposure shifting process. But by using the camera on Aperture priority, you can shift flash or ambient quickly. And you can do either one by changing only one setting.




Okay, so here's the room as seen in ambient light only. It's 90% memory-filled aging function room and 10% creepily empty, which is what drew me to this perspective. But I definitely want to call attention to that ceiling, which is getting no love from the ambient.

I can turn on the lights, but that's too much—and too warm given they are tungstens. So let's put a couple of flashes on the floor. We'll hide them with the door frames in a minute:




Doesn't get much more simple than speedlights on the ground. Their location is obvious now, but I'm willing to bet you didn't really notice it in the final pic up top.




So here's a first try, right out of the box. Not bad, actually. What's the exposure? Doesn't matter, as you should think in terms of relative changes and not absolute settings. It's the process that is important, not the f/stop.

We're on aperture priority (you'll see why in a minute) with a reasonable, middling aperture. I am starting at a mid-range aperture and at mid-range power on the flashes. You'd be surprised at how often that'll get you close right from the start.

But what if I want the ambient a little darker, without changing the effects of the flash? I need to move the shutter, but leave the aperture where it is. To do that in aperture priority, I'll just dial my exposure compensation button down one stop. Aperture stays the same, but the exposure will shift through the camera choosing a faster shutter speed:




There we go. Ambient has been dropped a stop but the flash remains untouched. That's why aperture priority and manual flash go so well together. And as long as my shutter does not go over 1/250th, I am fine.

It's looking kinda moody. Let's drop it another stop and see what happens:




Ambient gets a stop darker and the flash remains the same. Easy, right?

This is a little too dark for me. Totally subjective, though, and there is no right or wrong answer. But let's keep it dark and crank that flash up by remote control.

You know where this is going, right? We'll open the aperture and leave the exposure compensation where it is. Result should be a brighter flash and a constant ambient. What the hell, let's open it a few stops and go to wide open at f/1.8:




And the flashes go predictably nuclear. Too bright for me, but this is just as an example. But there are other changes you should be aware of, too. Depth of field is nill because we are wide open. And while the ambient is the same in most of the frame, the corners are much darker. This is because the Nikon 28/1.8 vignettes the bejesus out of the corners at wide open.

Not that there's anything wrong with that. I love vignetted, creamy background wide-angle portraits. But it is good to be aware of properties in your lenses and adjust accordingly. So I probably won't be shooting any wide-open architectural shots with this lens.

Let's close the aperture down some, and tame that flash a little:




The flash drops down a bit and the vignetting cleans up. (The latter fixes pretty fast as you get away from wide-open.) Also, we are getting some of our depth of field back. These are gross adjustments I am making here. But you can obviously choose to tweak this a third of a stop at a time if you like.

And don't fret about these multiple consequences of shifting your various exposure controls. As you get more comfy with it, you'll choose the changes that kill two birds with one stone in a positive way. It's really pretty intuitive once you have done it a couple of times.




Here's the final again, with the lines and walls cleaned up. (The 28 also had some barrel distortion, obviously.) Just a quiet photo, but an ideal way to show the quick-and-easy process of fine-tuning the flash, ambient or both right from the camera.
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Bonus points: For those of you who like to shoot sunset (or, shudder, sunrise) portraits lit with flash, you can see how this would make things super easy even with the quickly changing ambient of dusk.

Shooting in aperture priority, the aperture controls your strobe intensity. Exposure compensation button controls the intensity of the sunset. And aperture priority keeps you consistent as the light changes, allowing you to concentrate on more important things.


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37 Comments:

Blogger John Barker said...

Brilliant article Dave!

I was going to save up for some expensive stropes that I could control the power of via wireless, but I might just buy a couple of cheapo second hand units, to get me going.

Thanks.

February 18, 2013 3:30 AM  
Blogger Unknown said...

Excellent post DH. Reminiscent of the early days lighting 101.

February 18, 2013 4:53 AM  
Blogger John DM said...

sunrise is still a good hour away (you may well shudder), but it's good to start the day by learning something useful. Thanks, David

February 18, 2013 5:43 AM  
Blogger Rob said...

Nice and simple, Dave. I'll bet that there ar a lot of "Duh's" being heard out there.

February 18, 2013 8:20 AM  
Blogger Albert Li said...

Great article, David! Genius at using Aperture Priority to control flashes and letting the Shutter compensate. Would this work in multi-light set ups, like portraits with key, hair, fill? I imagine that you'd need all the ratios set, would love to hear your thoughts.

February 18, 2013 8:22 AM  
Blogger William Long said...

Good Monday morning "food for thought" whilst I putts around at my day job.

*sigh* Ah Mondays....

February 18, 2013 8:34 AM  
Blogger Perry A. Powers said...

And this is an excellent example of why I NEVER miss a strobist post...

February 18, 2013 10:10 AM  
Blogger shane said...

David, that was an excellent tutorial! So very basic but overlooked. I always shoot manual with flash. I'll give it a try, I am sure it will be an easier way to go, once I get the hang of it....

February 18, 2013 12:04 PM  
Blogger Wolfgang Kratky said...

Thanks for that great post. Fanboy :-) from Vienna, Austria here.

If I'm not completely wrong, this only works fine when you use a tripod and don't move your camera.

If you photog handheld and move the cam slightly, this might cause significant changes in your settings. (e.g. if more or less of the window is metered)

This is an effect you normally don't want, because the light in the room (in your example) stays the same, no matter if you have a little bit more window or more wall in the frame.

February 18, 2013 2:16 PM  
Blogger Myron said...

Love the sunsets, they seem to last forever, with the colors getting better after the sun goes down. Almost don't know when to pack up and go home. Sunrise is the opposite of course, colors fade into full sun back lighting. I guess I could just turn around and shoot the other way.
I had been using the Nikon CLS but it has a mind of it's own. I just bumped up from a D7000 to the D600, it seems to not be 100% cooperative. It seems manual setting might be easier and use less flash power.

February 18, 2013 3:40 PM  
Blogger Brian Bray said...

It's easy to remember if you use this:
A controls S, S controls A.

That is, aperture controls the strobe's effect, and shutter speed controls the ambient.

February 18, 2013 3:45 PM  
Blogger Frank Shernoff said...

Please correct me if I'm wrong (I'm shooting for less than three years and lighting for far less), but isn't it only metaphorical to suggest that one can control a speedlite via PC cord right from the camera? Conceded that shutter speed governs ambient and aperture governs flash, it is my understanding that flash OUTPUT does not actually change (let alone go nuclear) regardless of on-board settings. In fact, although not expressly stated, your post strongly suggested that your speedlite is in manual mode, and as such, cannot be controlled from the camera. Please set me straight! Your faithful reader, Frank.

February 18, 2013 4:19 PM  
Blogger Frank Shernoff said...

Another Mnemonic: SAAF (Shutter Ambient / Aperture Flash)

February 18, 2013 4:22 PM  
Blogger Wolfgang Kratky said...

@frank
you only can control the RELATIVE output of the flash (relative to the ambient). But in every case this relation is what counts for the resulting image lighteningwise.

(sometimes of course you need a very high output for a proper relation, specially when lightening in open sunlight)

February 18, 2013 5:03 PM  
Blogger Barnacle said...

great post!
thanks!

February 18, 2013 5:52 PM  
Blogger Darren Beckwith said...

Dave,

How would this change if you are in manual mode?

February 18, 2013 6:48 PM  
Blogger Frank Lanzkie said...

Wait wait wait.......how do you photograph a sunrise/sunset with strobes/speedlites???????????????? Can we get a post on this since you mentioned it at the end of this one?

February 18, 2013 6:57 PM  
Blogger Unknown said...

Frank, type "sunset portrait" into the box at the top left of the page. You will see some great posts that cover this subject. Have fun!

February 19, 2013 12:07 AM  
Blogger Fonk said...

I love aperture priority, but once I have to use exposure compensation, I just switch to manual. The primary reason being, half the time when I use EC, I forget to zero it out when I'm done, and I start shooting w/ it still set for the last session at my next session! I always know I have to adjust manual settings before I start in that mode, though.

February 19, 2013 2:00 AM  
Blogger Ian Pack said...

Great lighting with simple kit. Thanks for sharing this one David.

February 19, 2013 7:06 AM  
Blogger nikolai said...

This comment has been removed by the author.

February 19, 2013 8:55 AM  
Blogger Andrew said...

Very helpful post. One of those things we're supposed to remember but it never hurts to be reminded of. Thanks for the review lesson.

February 19, 2013 9:17 AM  
Blogger Brian Hursey said...

Wow I just had an derr moment. That is awesome why did I never really think about it?

February 20, 2013 7:48 AM  
Blogger Ron Ibarra said...

Thank you so much David! I can't even describe what this means to me!

I can finally get more use out of the PC cord without feeling like I am doing something wrong.

I have learned so much about lighting in the relatively short time that I ran across your Lighting 101 Posts and picked up a speed-light and off-camera set-up and started shooting with it!

February 20, 2013 9:53 AM  
Blogger Eric Bellamy said...

I had never really thought of using aperture priority for a shot like this. I've always been a manual only kind of guy. Other than being a little faster, how is there a benefit to using A/Tv in a location where the light isn't changing rapidly? It makes perfect sense at sunset or when clouds keep passing in front of the sun. But otherwise why not shoot on manual and not risk leaving the EC set for the next shoot, like Fonk said.

P.S. I have followed the blog for years but never commented. Time start contributing more.

February 21, 2013 1:30 AM  
Blogger Eric said...

Great post!
Is there a rule of thumb when it comes to how fast light diminishes during sunset or intensifies during sunrise?

For example: -1/3 stop every 5 minutes of sunset.

This would be helpful as a benchmark since sunset portraits can feel rushed. A benchmark for changing bg exposure would save time spent chimping for shooting.

Great post. Thanks!

February 21, 2013 1:41 PM  
Blogger David Hobby said...

@Eric-

That's the beauty of shooting against sunset on Av. Your shutter will walk down automatically, with your exposure compensation setting the relative value and you don't have to worry about tracking the fast-moving exposure changes.

#SoYouGotThatGoingForYou #WhichIsNice

February 21, 2013 4:52 PM  
Blogger Ivan said...

David,

You said: "We'll open the aperture and leave the exposure compensation where it is. Result should be a brighter flash and a constant ambient."

I know that aperture influences flash but doesn't the aperture influence ambient as well? Why doesn't the ambient change if you go to f1.8?

February 22, 2013 12:54 PM  
Blogger David Hobby said...

@Ivan-

Remember, we are in aperture priority (or, for Canon users, AV or aperture value).

So when we change the aperture (which changes the effect of the flash) the shutter inversely tracks automatically. Which preserves the ambient exposure. That's the beauty of shooting manual flash in aperture priority.

February 22, 2013 2:11 PM  
Blogger johnf said...

I read the article and kept saying to myself, why not just use Manual, and not worry about the exposure compensation - just seems simpler.... until I read your comment (David), on shooting portraits into a sunset. Light-bulb moment for me! Much appreciated!

February 23, 2013 11:44 AM  
Blogger Andrew Wisler said...

The only trick to using Av (for us Canon folks), and David did mention it briefly, is to watch you sync speed. I am embarrassed to say that more than once I have not been paying attention and in the heat of the moment (not being a steely veteran) have gotten the black bar of death because I let the shutter creep up too high (I know, worsened by Canon's sync speed limit). As you mentioned, shooting sunsets the shutter drops as you go. I, like David, hate sunrises so I don't have the opposite problem.

February 23, 2013 2:06 PM  
Blogger adventure_photo said...

Great post and advice but I think shooting in manual exposure mode is far better than aperture priority. Sure you can get it done in AP and exposure comp., but shooting in manual mode gets you thinking in terms of shutter speed and aperture. Flash too bright? Just stop down aperture. Need more ambient? Drag the shutter by slowing it down and allow more ambient to register. I find your technique of adjusting from camera is great for fine tuning but you'll still need to be in the ballpark, especially if depth of field is important and you need a middle aperture in which to shoot.

February 24, 2013 10:50 AM  
Blogger Gel Gidelim said...

Nice and simple

March 02, 2013 9:56 AM  
Blogger Peggy said...

Thanks for the tips David. As a beginner, this is really useful! I'll try this today :)

By the way, love your posts and the DigiRev HK show.

March 09, 2013 11:26 AM  
Blogger Akshay Singh Jamwal said...

Why the 'shudder' for sunrise?

March 13, 2013 3:13 AM  
Blogger Maria Jose Tobar said...

These are fantastic tips. I'm just barely getting into photography but I like learning all the stuff from shutter speed to camera flash in Beaverton OR. It's incredibly interesting, so thanks for sharing!

October 21, 2013 10:50 AM  
Blogger bryan flake said...

I have a Canon 5.1 Mega Pixel camera and the camera flash randomly stopped working. what could be the problem?

November 13, 2013 12:56 PM  

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