Coming to grips with flash again

Having purchased a new flash which only works in manual, I found myself having to refresh my memory on the workings of speedlights. I had taken an 8 week course on flash photography back in 2012 but did not have much opportunity to use what I had learned and have forgotten most of what I learnt on the course. So I’m finding myself working through some tutorials again.

I have always been pretty darn hopeless with maths so as soon as numbers get thrown at me I become very flustered. I was watching the video below on flash guide numbers and started to do the prescribed calculation on the computer calculator. Now apparently my Yongnuo YN660 has a guide number of 217 – nowhere in the manual does this number state whether it is feet or metres. Makes a difference, right? On the video the presenter explains that one has to divide the guide number by the distance and this will give you the aperture to use. The example he had was that his flash was zoomed at 105mm, had a GN of 112 and light source was 10 feet away from subject giving him an aperture of f11. Sounds simple enough. Well for the life of me I kept on getting an aperture setting f66 which couldn’t possibly be right. I really don’t know what I was calculating – maybe I threw the zoom figure into the mix, I really don’t have a clue.

Anyway today I decided to tackle this again. Went online and searched for a few sites to find the guide number of this flash and came across a site that stated the GN was 66 metres, and another which stated the GN was 217 feet. So I threw all the numbers into an Excel spreadsheet and punched in the formulas. Aha – the picture is looking a little better now. At 3 metres, full power my aperture should be f22. Now I can plug in the aperture settings for 1/2, 1/4, 1/8 power and on.

I also read a couple of Neil van Niekerk’s postings- one on dragging the shutter– balancing flash and ambient light.

  • For ambient exposure there are three controls:
    • aperture
    • ISO
    • shutter speed
  • For flash exposure there are four controls:
    • aperture
    • ISO
    • distance (light source to subject – closer = brighter)
    • power (increase/decrease – affects exposure)

There are two common denominators when we compare the two types of exposure: aperture and ISO. This means shutter speed becomes an independent control for available light source. The shutter speed won’t affect anything because the flash is instantaneous, while the ambient light is continuous.

The other video tutorial I watched again was Neil van Niekerk explaining how he used his “Black Foamie Thing” light modifier. I had made one of these for myself years ago but never actually got around to using it. Written explanations are on this page. I tried it out last Friday and seem to be getting the hang of it but want to get a little more comfortable with it before I post some images.

Reference List

Adorama TV (2016) Flash Guide Number – OnSet ep. 70 [user-generated content online] Creat. Adorama TV. 1 February, 2016. 4 min 48 secs. Available at: (Accessed 30 January, 2017)

van Niekerk, N. (n.d.) Dragging the Shutter [online] Neil van Niekerk Tangents Photography Blog. Available at: [Accessed 30 January, 2017]

van Niekerk, N. (n.d.) Video tutorial – Using the ‘black foamie thing’ [online] Neil van Niekerk Tangents Photography Blog. Available at [Accessed 30 January, 2017]


10 thoughts on “Coming to grips with flash again”

  1. Hah! Seems like you’re getting on brilliantly (pun possibly intended, once I think about it). Isn’t the shutter speed thing a wonderfully liberating thing to work out too?


    1. Just being bugged by digital noise though and I’m trying not to shoot more than 400 ISO even though my camera is supposed to be really good in low light — another thing to conquer I guess. Tips welcome 🙂


      1. Presumably the noise is happening in underexposed bits where your sensor isn’t getting enough information to drown it out. In which case, you could try slowing the shutter speed you’re using to balance out the flash to background ratio. Try Raw rather than Jpg as well, if you’re not already…


  2. I too have bookmarked this Lynda. I’ve had a Nikon SB600 for some years and still have not learned to use it properly – pure laziness on my part. You put me to shame!


      1. Your post prompted me to get my flash handbook out. That and the fact that I have a wedding workshop this coming weekend and reading through the pre course notes yesterday, I was reminded that I needed a working knowledge of my camera and flash. I know my camera pretty well but have only ever used the flash in TTL. Reading the handbook through last night it occurred to me that I need to do a course too. The trouble is that once you have attended courses you need to go straight back and put it into practice isn’t it? Good luck with your experiments, I will watch with keen interest!


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