Flash Diffuser for Macro Photography
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A suitable diffuser placed in front of the flash ensures even illumination with soft light and prevents glare on shiny surfaces. Diffusers for clip-on flash units from Cygnustech in Australia or AK Diffuser in Florida are considered to be good options for macro photography. These are tailored by the manufacturer to fit your specific camera-lens-flash combination, but must be ordered from maybe from abroad. The AK diffuser for a specific OM System combination is also available from the OM System shop (https://explore.omsystem.com - AK-macro-flash-diffuser-size-l). A ‘macro flash diffuser softbox’ by Guage is available in various sizes on Amazon. I had the opportunity to take a closer look at the ‘Small Size II’ model and take some test shots. It is very reminiscent of the AK Diffuser.
What bothers me about all these designs is that they’re a bit bulky for transportation. Even when taken apart, they don’t really fit into a smaller camera bag. After several attempts with a hard case, I therefore built myself this diffuser with a soft cover.
The diffuser is cut out of a lampshade. A suitable “Melodi” pendant light is available from IKEA for less than €7. The material is soft enough to be cut with household or nail scissors, and there is enough to make several diffusers. I clamped it onto an existing adapter ring. Depending on the lens, however, it can also be clamped in place with a filter adapter or secured with a piece of string.
The cover is made from an inexpensive folding reflector and sewn onto the diffuser. I pierced the holes using a heated needle. The ‘final assembly’ is carried out on the camera once it has been put together. It is advisable to cut the reflector fabric generously and then start by sewing the rectangular end piece that is wrapped around the flash head. Next, sew the opposite end to the centre of the diffuser panel and then continue along the edges from there. This works quite well for keeping the cover smooth and slightly taut once it’s in place. The excess fabric can then be trimmed off.
The diffuser works even without an outer casing. However, the casing ‘collects’ the light, resulting in an improvement of one f-stop. The colour of the surface – white or silver – makes no significant difference.
To ensure even lighting, it is necessary – as with commercial models – to use the flash in wide-angle mode.
The diffuser is not entirely colour-neutral. However, this can be easily and consistently corrected during RAW image processing, as the flash always emits light of the same colour. To this end, I saved the RAW image of a grey card with a diffuser as a ‘reference’. The colour shift can be easily corrected using the ‘Pick Color Eyedropper’ tool (in DxO Photolab). You can use ‘Image => Copy Correction Settings’ and ‘Image => Paste Correction Settings’ to adjust the white balance in the destination image, even if there are no neutral grey (or white or black) areas present.
A slight colour shift was also noticeable with the aforementioned diffuser from Guage. Some DIY instructions recommend 0.5 mm thick polystyrene or polypropylene as a diffuser material (available at Hornbach: white polystyrene sheet 500 x 400 x 0.5 mm); this also causes a colour shift, and tends to be even more pronounced than with the IKEA lampshade.
Here are a few tips on double-polarization flash technology.