Diffusion

Published: 15th Apr 2009
Updated: 2nd Dec 2009

Diffusion is a tricky thing! I've been running some tests recently, since I encountered trouble with specular reflections shooting a Lacewing last week.

For a long time I've been using a kind of thin packing foam as diffusers. I originally got some wrapped round a new LCD monitor. This worked very nicely. Over a period of time I acquired various pieces of similar foam, and have been cutting all sorts of little flash diffusers from all these bits of foam, assuming they would all work as well...

Wrong! After someone else pointed out that foam doesn't diffuse as much as you might think, I started looking more closely at the different pieces of foam I was using. The original stuff which worked well is white to look at, you can not see through it, and it has a fairly fine 'grain'. The piece of foam I was using on the Lacewing had a very different structure. The 'bubbles' in the foam are much larger, and more transparent. Hence it was not diffusing the light as much as I wanted.

The next experiment was some paper. Kleenex tissue was advised but I was fearful of small bits of fluff coming off of tissue paper onto the specimen so my first tests were with a bit of standard printer/copier paper.

This diffuses extremely well. In fact, I think it diffuses too much!

Bee face photo, light _heavily_ diffused with copier paper

Here's a comparison shot with some foam:

Bee face photo, light more lightly diffused with thin packing foam

At full resolution there is slightly more detail visible in the hairy parts of the bee in the first shot (with the paper diffuser). However the consensus seems to be that the second shot looks better. The light is just too flat in the first image.

Of course some subjects require much more diffusion than others - for instance Beetles, particularly black Ground Beetles and Ladybirds. So I guess it's best to have a variety of diffusers available, and test diffusers on each subject before going through the whole stack!

One of these days I will get around to purchasing some proper diffusion material (e.g. from these people but I enjoy the hunt for junk that can be re-used!

2 Comments so far. Post a comment

Do tell me if you find out something good about diffusers. Currently I'm using this bottle diffuser:

http://malmberg.smugmug.com/photos/496423557_ukDNV-S.jpg

sagarmatha at 01:45 on 29th Nov 2009

I came across your work on flickr recently and just a few days later I stumbled across your site for something completely different.

I must say this comparison is incredible! The second less diffused one is generally more aesthetically pleasing with the contrast but I do find myself preferring the the first one; it almost looks like natural light. Each has its place I suppose, the catchlight brings out of a lot of detail in compound eyes.

Brodie Foster at 09:37 on 2nd Apr 2010