Bubutbut

I often, of course, say this – “Limit: when using flash, you cannot exceed your camera’s fastest sync speed (usually 1/250th second)”.

And then almost as often, I hear the following objection:

“But Michael: you can use High Speed/Auto FP flash!”

And that way, you can exceed the sync speed. Sure – like in this photo of Aurèle Monfils of the Porcupine Photo Club, which I made yesterday with the standard sunny day blurred background setting (write it down!) of:

  • 100 ISO
  • f/4
  • 1/2000th sec

…using an on-camera flash fitted with a Honl 8″ Traveller 8 softbox:

Yes. You can, as you see!

But now I have a “but”.

The high-speed mode works by effectively making your flash into a continuous light, at least for the duration of the shutter speed; it flashes pulses at 40 kHz. Fine, but most of those pulses reach the closed part of the shutter, so most energy is wasted; hence, your effective range is reduced dramatically. Maybe just over a metre at 1/2000th second when using the flash without modifier; with a softbox as I was using here, maybe 30cm, no more.

Hence the slight “wide angle” look in my image above due to me having to be close, with a wide lens. As in this one of Aurèle’s daughter Lisa:

So while it is true that high speed/FP flash solves the sync speed problem, it’s  not a panacea, and in practice, it is only occasionally usable.

Footnote: Lisa is turned away from the sun: It is behind her, meaning she is not squinting, and the sun becomes the shampooey goodness™ light on her hair!

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Want to learn to use modern Flash technique? I travel worldwide for hands-on seminars. Vegas, London, the Netherlands, Phoenix, Niagara, Toronto, or Timmins: wherever you want me, I’ll be there for you.


Beginner’s Flash Mistake

Has this ever happened to you?

You want an outside picture with a blurred background. So you set your aperture to a low number, and click, a nice enough picture.

But your subject is a little dark, so then you realize “wait – I should have lit my subject with a little flash”. So you simply turn on your flash and change nothing else. And then this happens:

Whaa? What happened?

Ah. In the first picture, you were at 1/1600th of a second, say. But you forgot that you have a maximum flash sync speed – usually 1/200th to 1/250th second. So for the second picture, the moment you actiavted the flash, your camera said “oh, my owner is using flash. I am slowing down the shutter to the sync speed, whether he/she likes it or not”. The result: a grossly overexposed image.

Solution: either use a slower shutter and a higher f-number and forget the blurry background, or activate “high speed flash” (“Auto FP flash”, as Nikon calls it), where the flash emits a 40 kHz pulse of little flashes, so you can go beyond the sync speed, and you can keep your f-number low. Now you get this (shot at 1/1600th second, f/2.8, 100 ISO):

Problem solved!

Note: That “fast flash”mode is only available on speedlights (like the 600 EX/SB910). And there is a drawback: your range is significantly reduced. In the previous picture your flash might reach 10 metres; with fast shutter speed and high speed flash it can be as little as a metre or less. So it’s good when you are close, as I was here.

 

 

What’s this Hi-Speed flash thing again?

A reminder for all you speedlighters.

Say you want a shot like this, taken a few days ago,with your Nikon D90 or whatever SLR you have equipped with an external flash (like an SB900):

Yes, direct on-camera flash, when used outside and hence mixed with available light, can give you this – not bad eh? And the picture isn’t bad either. 🙂

But look at the background. It is blurry.

That means a large aperture was used (f/5.0 in this case).

But that means the shutter speed must have been very fast – even at low ISO, you need a fast shutter on a sunny day if you want the aperture to be large. I used 1/2500th second.

But hang on. When using flash, you cannot exceed the flash sync speed! Which is 1/200th second on this camera.

So how did I do this? I enabled “fast flash”. (“Auto FP flash” is what Nikon calls it; Canon calls it “High Speed flash”). On a Nikon, go into the flash part of the pencil menu and find flash sync speed, and set to Auto FP. On a Canon flash, indicate the little “H with a lightning symbol”.

Now the flash, whenever you exceed the sync speed, pulses rapidly instead of firing all at once, meaning that you can shoot at fast shutter speeds, where the shutter never fully opens all at once.

The drawback is that most power is lost, so you need to be very close. Aim the flash forward and watch the indicated flash range: as soon as you exceed the sync speed, that range drops rapidly. Stay within that range and you get great outdoors flash pictures!

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NOTE: Come join me for a five day workshop at August’s Niagara School of Imaging – it is filling up but there is still space. Act now and spend five days with me on all this stuff, and emerge a flash pro.

 

In the eye of the…

Take a day outside. You want to shoot a snap of a pretty model.

If you are Uncle Fred, you shoot in the “AUTO” mode. Or in Program, or even in Aperture mode, with a large aperture (low “F”-number), to blur out the background. OK, here we go. SNAP:

But because you read Speedlighter.ca, you realise that background should be darker. So then you shoot again, after setting exposure compensation down two stops (-2). That gives you 1/1000th second, and the image looks like this:

Mmm. So now you need to turn on the flash (and again, you know this because you are a Frequent Reader here).

So then you do this – and you get this:

Oh. That’s right. The flash sync speed is 1/200th second, so your camera will not allow the 1/1000th second shutter speed you need. So the image is overexposed, at 1/200th second.

OK-  so now you use Fast Flash (“High Speed Flash”, on Canon, and “Auto FP Flash” on Nikon). And you move close, very close – or you have insufficient power.

That gives you this:

Nice.

But could that shadow be softer? Yes. So you put a Honl Photo softbox on the flash – yes, you can use a softbox like this on the on-camera flash – and now (after once again ascertaining you are close enough – even closer now, since the softbox loses some light too), you have the image you were after in the first place:

Compare this excellent image with the snapshot image at the top and you see why it pays to know flash techniques, and you see why I am passionate in teaching them.

 

High speed flash

Tip of the day:

When using your flash outside, you have to be careful: you cannot exceed your camera’s maximum flash synch speed – normally around 1/200th second. This means in bright light you cannot use a wide aperture like f/4 (which after all might mean you would need 1/800th second, say, even at 100 ISO).

But if you have a suitable external flash you can exceed that speed (the flash pulses at 30 kHz-50 kHz instead of flashing all at once).  If so, high-speed flash, or FP Flash, can be engaged on your flash.

On Nikon cameras, and on Canon cameras built after 2005, you can leave this on, and it will engage when the speed exceeds your flash sync speed, but it will not be used if not needed.

The drawback of fast flash: you get less effective power. Half at best, at smaller apertures much less. Meaning less flash range: but at least you can get outdoors portraits with large apertures.