Advice on flash diffusion

paddler4

I would appreciate advice on diffusing flash.

For a few years, i was unsatisfied with my flash rig because of the extent of reflections I would get off eyes and shiny parts of the body. So, I built myself a coke can diffuser, which I have held next to the front of the lens, like this:



My initial diffusion was two sheets of parchment paper and a sheet of Manfrotto 219 diffuser. This was giving me a lot of glare, so I rebuilt it today with one sheet of parchment, two layers of paper towel, and a sheet of 219. That is a LOT of diffusion. However, I am still getting some unwanted reflections. It's windy out today, so I didn't get really good shots, but I got some that show the remaining problem, like this wasp:



and this slightly OOF honeybee (note the eyes):



These were shot with my standard 1/125, f/13, ETTL flash. I have been using FEC to try darkening the shots, but I think it is the total dynamic range that is messing things up; I would have to darken the image a large amount to avoid these reflections.

Any suggestions about what I am doing wrong or could do differently?

Thanks very much.

Dan

ian408

Try moving the flash farther away or cut the power (manual mode on the flash).

Lord Vetinari

Hmm tricky one.
You are right that the amount of diffusing sheets on the end of the coke can should be enough. Part of the problem I suspect is actually the lens to subject distance. The closer the flash diffuser is to the subject the better so it's easier to diffuse for high power macro shooting.
Firstly I'd set something up to test any diffusion changes. I often use two little plastic headed pins stuck in something like blu tac plasticine or similar as a standard target.
Try using a standard target in ETTL mode on the flash firstly without any sheets on the front of the diffuser and then try adding them one at a time and take a test shot each time.
You could also try it with and without the flashes built in wide angle diffuser (assuming it has one).
I actually tend to use higher ISO's now to try and let in some natural light and obviously this reduces the flash strength needed.

For good diffusion you need both diffusion sheet plus a large effective light source size compared to the subject.
Anyway try a few things oput and believe me it is much easier with a suitable fixed target to look at the results.
See example here https://www.flickr.com/photos/lordv/2991229609/in/set-72157594293307036
Brian V.

paddler4

Brian,

Thanks very much. Very helpful, as always.

Dan