2010-10-11

DIY Macro Photography IV: On-Board Flash Diffuser

As I get more into macro photography it has become clear that lighting is absolutely critical for good results   The best way to achieve good lighting appears to be one or two external flashes mounted on a bracket.  This allows you to have loads of control over the light sources.

However, in the truest bodging spirit I decided to see what I could do with just a few bits of rubbish I had lying around.  Obviously this rules out using external flashes and brackets.  Despite this I thought I could probably do a bit better than just using the on-board flash on my camera.  The plan was to build a snoot / diffuser to direct and soften the built-in flash in a way that fitted my macro set up.


Ingredients
  • Cardboard tube
  • Aluminium foil
  • Duct tape
  • Kitchen roll


Construction
The first step is to cut down the tube to size.  I wanted the tube to reach the end of my macro lens, but also to have a bit of a an angle at the end.  I used my mitre saw to chop the tube down to the angle I wanted:



I also decided to cut a small notch in the opposite end of the tube to make it fit slightly better against the built-in flash on my camera:





Once this was done I did a quick test fit to ensure all the dimensions were as I wanted:


I decided that lining the tube with aluminium foil would be a good idea.  I imagine this will help minimise light loss.  As the flash on the 7D is a bit weedy I need all the light output I can manage.  I cut some foil to size allowing enough for double thickness when rolled up and also a good edge for securing the foil to the tube:



Fitting the foil to the inside of the tube proved tricky until I realised that the fuel bottle for my camping stove was a perfect fit inside the cardboard tube.  This allowed me to use it as a blank around which I could wrap the foil and insert it into the cardboard tube:







Once the foil was inside the cardboard tube I cut tabs into the ends to allow it to be folded back and secured to the tube:



To make the diffuser a bit more robust I decided to wrap the whole thing in duct tape (bodge tool #1).  I paid particular attention to the ends of the tube where the foil was folded back.  The foil is not very robust, so some protection here is a good idea:


Once the foil lining was in good shape I fitted a diffusing element to the business end.  I used some kitchen roll, but any translucent material would be suitable:


One final feature I decided to add was a foil-covered cap for the camera end of the tube.  This simply hinges on a piece of duct tape and sits behind the flash head.  Again the idea is to try to direct as much flash energy forwards as possible.  I'm not sure if this makes any difference, but it does reduce the bounce-back you get when using the camera.




Once construction is complete it's a simple matter to fit the tube to your camera with some strategically placed rubber bands:


Results
Overall this modification works very well.  The snoot directs the flash quite nicely and really pours light on the subject.  I still have a few issues in my macro setup with vignetting, but that's a lens issue that I will address some time in the future.  Here's a few test shots:
SD card contacts

Zippo flint

Dead fly

2 comments:

  1. Hello,

    Thanks for posting this, interesting. I was considering doing this but not so sure after seeing the result - that's a fairly harsh shadow in shot #3. I think the light source needs to be broader to give a softer shadow, so this sort of idea that's slightly wider near the subject (ie wrapping 180 degrees around the lens) might be the answer - exactly the cutout I have on my desk right now in preparation for a bit of DIY action tonight. I do reversed macro as well so face similar challenge, except I do use a bracket mounted flash.

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  2. Hi Johan,

    That's a fair comment - this bodge is perhaps a bit too much snoot and not enough of a diffuser. I'd be interested to hear how you get on with your DIY project.

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