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Monday, June 28, 2010

Concave Diffusers

Since the concave diffusers seem to be in the trend now, and the light from these were really well diffused with no hot spots, I had to make myself a pair of concave diffusers as well.

Prior to this, I have been using my version of "cup diffuser" for the MPE65 1X-5X macro lens / MT24EX macro twin flash combo for a couple of months now and loving the light from it. More about the cheap yet great DIY Concave Diffuser here.

About a week ago, I tested out the "concave top diffusers". It looks like this:

the opening on the one on the right hand side goes onto the MT-24EX flash head. The one on the left is upside down for comparison
DIY concave diffuer IMG_9558 copy

the same pair from a different angle
DIY Concave diffuser IMG_9559 copy

The opaque concave tops are from those toy capsules widely available from toy vending machines in most convenient stores/sundry shops in Malaysia.

DIY Concave diffuser - Where to get the concave tops:D

how it looks like when fitted onto the MT-24EX and MP-E65
DIY Concave diffuser IMG_9562 copy

front view of the setup
DIY Concave diffuser IMG_9561 copy

The housing, as you can see, are from Justea packet drink (Tetra Pak drink packaging). It was actually quite a task to make the housing fit snugly onto the MT24EX flash heads. However, you can use this moldable plastic to make housings that fit nicely onto the flash heads.
 InstaMorph - Moldable Plastic - 12 oz


lower angle
DIY Concave diffuser IMG_9560 copy

Surprisingly, additional layer of diffusion from the concave top actually almost doesn't cause any loss of light as evident in the following quick tests:

without the concave top, i.e only with tent/cup diffuser. At 1:1, ISO100, F11, 1/200, i need 1/4th flash power to light the scene.
DIY Concave diffuser IMG_1254 100crop copy

with the concave top and also the tent/cup diffuser i.e extra diffusion. At 1:1, ISO100, F11, 1/200, i need the same 1/4th flash power to light the scene.
DIY Concave diffuser IMG_1252 100crop copy

Now the 100% crop images of the above:

without the concave top diffusers:
 DIY Concave diffuser IMG_1254 100crop

with the concave top diffusers. Noticeably nicer/less harsh specular highlight there.
DIY Concave diffuser IMG_1252 100crop

However, even with the slightly better handling of highlight, my latest concave tops plus cup/tent diffuser still can't pass the ultimate test: the golden tortoise beetle! In fact, i failed miserably :D

blown highlight all over, even at -2 FEC (flash exposure compensation).
DIY Concave diffuser IMG_1317 copy

Maybe I need to look for some Vellum paper to replace the polyfoam sheet I'm using for the cup/tent? Still looking for a shop in town that sells it.

To be fair to the awesome tent/cup diffuser and concave tops, I need to point out that I had tried shooting a golden tortoise beetle with just natural light and still ended with blown highlight. But next time, I'll try to use a CPL.

Note: the concave top diffuser is the brainchild of SteB1 (Stephen). If you would like to read more about his excellent analysis of various diffusion methods, check out the following:

Some Ideas on Macro Flash Diffusion

and

Concave Flash Diffuser Test

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