Deterministic flash

Flash phenomena may seem stochastic, but they are deterministic. Look those words up if you like; what I mean is that whatever happens, it’s predictable, not random. When something goes wrong, look for, and find, the reason. If it seems weird, you just haven’t found the reason.

Yesterday, I ran into three curious flash phenomena in one day.  And just for fun, I’ll run them by you. So you’ll learn to solve these things by yourself.

*** 1. THE CASE OF THE MISSING TTL. You turn on your Canon 580EX flash, and instead of the MODE button toggling it between “ETTL” and “M”, it toggles between “e” and “M”. What gives?

Solution: you set something weird in the custom settings, and TTL has been disabled. Solution: set the custom settings back to default. Use a connected camera to do this, or read the manual for instructions for doing it manually.

*** 2. THE MYSTERY OF THE FIVE EXTRA STOPS. This is a common one. We set up everything properly, but the photo looks like this, at least five stops overexposed:

Solution: this is due to the flash firing at full power, instead of at the correct  lower power as calculated by TTL. The reason for this is almost always the same: a bad contact. For the TTL mechanism to work properly, all five contacts need to be good. And millivolts are easily lost if a contact is dirty, say. So sure enough, after cleaning the contacts, all went well:

*** 3. THE CONUNDRUM OF THE “A” THAT SHOULD BE AN “E”. The flash toggles between M and TTL, but instead of the usual “ETTL”, I see “ATTL”. ATTL was an earlier iteration of Canon’s TTL mechanism, while ETTL is the most recent version. Mysterious!

Solution: Here too, the reason was a bad contact. The phenomena that can result from bad contacts are legion. Cleaning the contacts worked: now I got normal ETTL again.

In my years as a photographer, I have seen many things go wrong with speedlites. I have found that although many things can be the cause of the malfunction, it’s usually settings or contacts. Check those before you do much else.

 

High speed flash.

High Speed Flash. Also known as High Speed Sync, or HSS, or “Auto FP” flash. Your camera/speedlight combination probably has it. Let me explain what it is, why it’s good, and why it’s nevertheless seldom useful.

First, the term “High Speed” is a misnomer, since it is actually slow speed flash. Let me explain.

Normally, a flash lasts 1/1000 sec or less. At 1/32 power, it’s only about 1/30,000 second. Very, very fast.

But there’s a problem: the shutter cannot keep up. You see, the shutter needs to be fully open for that quick flash to be able to illuminate the whole sensor, but at speeds above 1/250 second, the camera makers use a trick to get faster shutter speeds: instead of opening fully, an ever narrowing slit of light travels down the sensor, so the shutter is never actually fully open.If you try to use flash, only part of your picture will be illuminated.

But there is a trick: HSS, or “Auto FP” flash. When using HSS, instead of flashing once, the flash goes FlashFlashFlashFlashFlashFlashFlashFlash very rapidly (at a rate of 30,000 times a second).  This makes it into what is effectively a continuous light. As the narrow shutter slit travels down, the FlashFlashFlash keeps going on and hence the flash illuminates the sensor gradually.

So, set your camera (Nikon: camera menu, select “Auto FP” flash sync) or flash (Canon: set flash to HSS symbol) to high speed and you are set to go. You can now use any shutter speed, up to whatever. 1/4000? Sure. Go for it.

The problem? HSS loses most of your power (you are illuminating the closed part of the shutter, after all), so your flash range is reduced. At 400 ISO and f/8, my flash has the following maximum range:

  • 1/30 sec:     9m
  • 1/60 sec:     9m
  • 1/125 sec:   9m
  • 1/250 sec:   9m
  • 1/500 sec:   3m
  • 1/1000 sec: 2m
  • 1/2000 sec: 1.5m
  • 1/4000 sec: 1m
  • 1/8000 sec: 0.7

So up to 1/250, varying the shutter speed, as you would expect, has no effect. But then HSS kicks in, and the range starts to drop dramatically. At 1/8000 sec, my flash, at full power, only reaches 70cm (about 2 ft). And if you are using a modifier, like an umbrella, forget that: you would be lucky to get a few inches.

So while HSS is a great idea, it is not very useful in most practical situations. Because you are most likely to need to need it when it is bright outside, but that’s also when you need most power and cannot afford to lose any. Catch-22, since HSS steals from Peter to pay Paul. Now you know.

Math buff note: can you see any math logic in the numbers above? Yes, every stop faster shutter speed loses you the square root of 2 (roughly 1.4)  in available range. So, two stops faster shutter means half the range.

 

Less is more.

Sometimes, simple is all you need. Like in this headshot:

This shot is simple in many ways:

  • Shot with simple camera settings: f/5.6, 1/125 sec, 400 ISO.
  • I am using just one flash on camera, aimed 45 degrees up, behind me. The catch lights are the circle that my flash throws onto the ceiling.
  • The flash is using TTL (automatic flash metering, in other words). Of course since this is a high key scene, I set flash compensation to +2 stops.
  • I am filling the frame. Yes, cutting off the head is allowed.
  • The pose is a simple one, as is the composition.
  • The location is a simple white bathroom: smaller is great since it allows great bounce without the high ISO values you would otherwise need.
  • The dress is a simple white shirt, against a simple white background.

All this “simple”, combined with the right model and a razor-sharp (obscenely sharp, some might say; look at full size) 85mm f/1.2 lens, makes for a good shot. No studio complexity needed in this case; no pocketwizards, no complicated anything. Simple does it; less is more.

So if anyone tells you “you cannot do this, you need more equipment”: it ain’t necessarily so!

 

Things you can’t do

There are many things that conventional wisdom says you cannot do. Like shoot at slow shutter speeds when people are moving.

But I say you can, and damn the rules.

Like this, of baby Aubrey and her dad Dave at her 1st birthday party, which I photographed the other day:

(Shot at f/4, 800 ISO, 1/30 sec; focal length 35mm using the 16-35mm f/2.8 lens).

I used a flash, bounced as usual up, behind me. The challenge is white balance: I could have gelled my flash the same colour as the light, but that was difficult under the circumstances, so I ended up with blue and red light mixed. Not to worry, the compromise white balance, where I balanced mainly for the tungsten spotlight, since the baby is more important than the tables in the background, is just fine.

Back to the shutter speed. It was 1/30 second, and with the baby waving her hands and feet this of course causes unsharpness. In this case, the unsharpness is not a problem. It shows the fact that the baby is happily waving her arms and legs to show that she is delighted to be the centre of attention. Without that, the photo would have been boring. With it, it shows the joy of the occasion.

Success, even though you are not supposed to do this, 1/30 sec with rapid movement in the subject.

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Shoot

Last night I photographed a party. Let me take you through that: it is useful to see a real-life shoot as it unfolds.

This was a very quick, rushed shoot: hardly any time at all to set up.

I had two cameras:

  • 1Dx (full frame) with 16-35 lens;
  • 7D (crop camera)  with 24-70 lens.

That means effectively I had 16-35 and 35-105 mm available, i.e. 16-105 in one continuous range. So the lenses were taken care of.

Now the lights. Seeing the need for speed, I quickly set up two speedlights in umbrellas, fired by Pocketwizards. In this example only the one on the left fired:

The final pics look like this:

That’s simple: One umbrella left, one umbrella right. We are looking for competent lighting here, not art. I did not use a meter; just set the lights to 1/4 power and adjusted ny camera settings (ISO, aperture) to that.

Note the mom in the first shot. My shoot was hindered big time by all the moms taking iPhone shots. A trend more than ever before.

Then the rest of the shoot: the 16-35 with one on camera flash bounced against what walls there were.

Easy in some rooms, harder in the ballroom since it had a high, black ceiling. So I started at 400-40-4 modified to 800-40-4: i.e. a camera setting of 800 ISO, 1/40 sec, f/4. That extra stop comes in handy when you are bouncing off high or dark ceilings. Like here, in the middle of the ballroom

Sometimes, I switched to mood lighting: simply increase the shutter speed to darken the ambient light, and the aperture smaller (or lower flash compensation, when on TTL) if you also want less flash:

All in all, a competent shoot.

With some fun too: A panning shot., 1/30 sec and I follow:

The ghosting lends it an interesting effect; and the subject is sharp first because I am panning; second because she is lit mainly by my flash, which is 1/1000 second or faster.

I had just enough time to produce prints for the parents, on my little Selphy printer. All good.

And then quick post work an on to the next assignment!

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