The self-lighting €85 flash

About three weeks ago I ordered a new flash from ebay – a new $85 dollar flash, that is.  It – a Yongnuo YN-560 – arrived yesterday, and with VAT and a handling charge courtesy of the Revenue Commisioners and An Post, it ended up costing just shy of €85.  That’s exceptionally cheap for a flash that has a built-in optical slave, a zoomable flash head, variable output from 1/128 to full power, and a power output comparable to a Nikon SB-800.  I’ve only just started playing with it, but I wanted to post a photo of it today, so I set myself a challenge: to photograph the flash using only light from the flash itself.  The result of the challenge is above.  Here’s how I did it.

Just so we’re clear, the rules I set myself were as follows:

1. The image had to be a single exposure – not a merge of multiple exposures
2. The only light source was to be the flash that I was photographing, and so the flash had to fire during the exposure
3. I was allowed to use another flash as a trigger, but had to verify that it was adding no light whatsoever to the exposure.
4. Minimal post-processing was allowed

To further complicate matters, I started this process at about 7.20pm and I had to leave by 7.40pm to get to Dublin Camera Club for 8pm, so it was a time-limited task.

The challenge required me to think carefully about where I positioned the flash, and what I positioned around it.  I knew that, to avoid flare, I would have to point the flash head away from the camera, otherwise as it fired during the exposure it would wash out most of the frame – something that I was able to quickly prove with a test shot.  The problem was that pointing the flash head away from the camera meant firing all the light that I was allowed to use away from the subject, so I needed to direct the light back towards the subject somehow.

My solution was to use a simple law of physics that dictates how light travels – that the angle of incidence equals the angle of reflection – and to use a simple device to efficiently point the light from the flash in a more useful direction.  That device: a mirror.  The mirror from the downstairs toilet, to be precise.

Here’s one view of the setup, taken from close to where the camera would be positioned for the final shot, you can see the mirror and where it is relative to the flash.

The flash itself is sitting in an ad-hoc table top studio “built” from five pieces of 20″x16″ white card that I had been using as backing board for mounted images last week.  Two of those pieces of card are the floor of the studio, a third is the wall at the right, which is setup to act as a reflector to hopefully throw some light on the right hand side of the flash.  A fourth piece is acting as a back wall, but this is angled.  The reason it is angled is purely because  I didn’t want to cut or fold it, yet I needed to stop it from blocking the path from the flash head to the mirror.  It is primarily there just to help bounce light around.  The fourth piece of card, just visible at camera left, is again trying to be a reflector to throw a little light on the camera left side of the subject.  I don’t imagine this was particularly effective, but it was doing no harm to leave it there.

A second set-up shot shows the role that the mirror is playing, and also shows how I positioned everything in the room.

The key to getting light back on the flash is to bounce it off two surfaces.  The first – the mirror – directs light (relatively efficiently) towards the second – the corner of the room where two walls meet the ceiling.  This second surface sends light back towards the flash, but in a diffuse manner because it scatters it.  That means it’s an inefficient light source, but one that throws light right where I want it – on the camera side of the flash.  You can see from this second setup shot above that the corner of the room now is a large light source itself, and so is emitting soft light.

For the final shot I had use of a fifth piece of white card (which I wasn’t able to show in the setup shot).  This was held in my left hand and carefully positioned to hover over the flash, but in a way that didn’t obscure light from the mirror travelling to the wall, or light from the wall travelling back to the flash.  What it did do was act as another reflector to give the nice highlight on the top of the flash head.  Without it, that surface of the flash was too dark.

The flash is set in S1 mode, which means that it acts as a dumb slave to any other burst of light, and so it’s triggered from an SB-800 that I have mounted on my camera, set to minimal power (1/128th power) and pointing straight down to the floor when I hold the camera in the vertical orientation I used for the photo, so that no light from that trigger is hitting the subject.

The shutter speed is set to 1/200s and the aperture is f/5.6, with an ISO of 200 – these ensure there is no ambient light registering in the exposure, and the aperture is kept relatively wide to avoid me having to go to full power on the flash – because after 8 full power bursts, it times out for 3 minutes to prevent overheating.  Not very practical, but it did only cost €85.

To prove that all the light in the frame was coming from the subject and only from the subject, I kept everything the same but switched the flash to M mode, turning off the optical slave.  The resultant frame is suitably dark:

So here’s the final shot once more, where you can hopefully begin to see the impact of the various pieces of white card I was using and how they help illuminate different surfaces of the flash.  It’s not the best product image in the world by a long shot, but not many get lit only by the product itself!

Incidentally, the flash power I was using was 1/8th power – you can see this in the final frame.  I stayed at this power level because the flash would allow me shoot continuously without going into overheat-protection mode.  I haven’t verified it myself yet, but I believe that even at 1/4 and 1/2 power it can time out for 3 minutes after a fixed number of bursts. Even at just 1/8th power, the flash was throwing out enough light to bounce off a mirror and back off a wall to illuminate itself at f/5.6, ISO 200, which is quite an achievement and suggests that those claims about it packing as much punch as an SB-800 aren’t too far off the mark.  I did help it along by zooming the flash head to 105mm.

As I play with the Yongnuo YN-560 more I’ll post about it, and no doubt it’ll be used in future photoshoots thanks to that very useful optical slave.  I should mention that a Canon-shooting friend ordered one at the same time as me and has found it isn’t firing when on the camera.  That may be a quirk of his unit, or be a wider compatibility problem with Canon, but I’ve not seen issues with mine on my Nikon D700, nor have I yet tried his on my camera.

At a price of €85 I guess it’s possible that the reliability is hit or miss – David Hobby had problems with his unit as reviewed on Strobist also – but when it works – as mine appears to do – it looks like very good value.