DIY flash diffuser

[Slipper]

Following several threads I read on here and advice given, I made a flash hood. Compound angles are a mystery to me, but I had lots of tape.
I got a Nilon SK-7 bracket, this seems a solid bit of kit and works well. The ball head is a RotoLight 360 Pro, nicely made if a little light. Good for the flash though.

The diffuser was two kitchen tissues.






Still some hot spots, needs more work I think I have more tape

[DanK]

Looks like it is working very well. I think it is very hard to avoid hot spots with bottle flies, since their carapace is shiny. In general, I'm disappointed in the hot spots with my new diffuser and plan to replace a layer of parchment with a piece if paper towel.

[deetheturk]

Well done, as Dan says it seems to be working, my latest is a MacDonald's large drink's carton

[ajohnw]

David's diffuser works so well I wonder if it lets any light out from the flash at all.

I still think the answer to the problem is two fold. A diffuser helps but if the light can be applied at an angle were no reflected light off a shiny part goes straight back at the camera there shouldn't be a problem anyway. The problem is similar to red eye. Use the right sort of flash bracket on that and it disappears.

My simple set up doesn't seem to be too prone to it and I am yet to add a diffuser.

John
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[Slipper]

@DanK. Thanks Dan. I hadn't thought about the reflectiveness of the fly, good point.

@deetheturk. Dont drink too many though David, but good idea. Thanks.

@ajohnw.. I will keep trying angles John, thank you.

[Geoff F]

I tried a diffuser once; absolute waste of time for me. In fact everything was worse. Even tried a polariser with similar disappointing results.

A lot depends on your shooting settings but if you can see hot spots on your subject they will still be there no matter what set up you use. Unless you massively under expose which ruins your midtones and shadows.

If you have your flash output on manual option it works like an old fashioned fixed output flash; in which case some diffusion/flash reduction is necessary. But modern 'auto thinking' flash units will vary their output to suit the scene. It took me some time to realise this when I got my first Speedlite and my early shots were a disaster because I was still shooting with old theory.

Which means that adding any obstructing material to the flash head simply tells the camera to increase the auto output. So it won't have any difference until you have darkened it to such a level that you have gone beyond the camera's ability to auto add more compensation.

But although modern variable flash output is good there will be times when some compensation is required, just like applying a little Exposure Compensation for those difficult scenes.

So for flash photography, I set the camera manually to suit each individual scene then give the flash output a little tweak, if required.

But remember there are always some limitations such as shutter speed which must be sufficiently slow to suit your camera (eg 1/250) or use high speed flash; although this can reduce the effective range.

For insect macro work my typical camera settings in manual would be 1/160 to 1/250; F11 to F16; Iso 200 to 400. All depending on the ambient conditions. Then tweak the flash output compensation as required.

As always, there are exceptions and in some cases you may want to shoot with the flash unit in full manual mode. Now you will find that any diffusing material works in the same manner as those old fashioned units. Using various flash angles or home made light extension tubes etc can direct the flash angle to a different direction which can be beneficial at times; but always be aware of creating other problems elsewhere.

Much of my insect photography means shooting down 'holes in the foliage' so I normally just use the standard flash mounting.

Incidentally, I was trying to photograph a bug today and was getting excessive hot spots, even when shooting without flash. So there was only one answer, hold a piece of card to block the sun (or suitable diffusing material). The danger with this method is that beside frightening your subject there is a risk of getting too slow a shutter speed and ending up with motion blur from wind rock or subject movement, even when using a tripod.

[ajohnw]

Must admit I wonder about diffusers Geoff. If an insect is shiny it will reflect and that can result in specular highlights. I did see some shots taken by some one who was just starting out and I had mentioned max flash sync speed and through the lens. They went out and bought the most powerful flash they could afford and promptly posted some over exposed images., Later added some cardboard etc and all was ok probably down to light loss. Flash guns do have minimum exposure levels - it's a tiny fraction of a second but the more powerful the gun the stronger that tends to be.

I'm going to try one anyway in case there is some sort of lens effect down to the shape of an insects body and the size of the source plays a part. It's hard to dismiss the fact that reflective surfaces reflect full stop.

Different angle would work but the penalty is likely to be shadows. It's not unusual for me to see the flash contributing over 3 EV

I have a multi volume treatise on macro and micro photography. It looks at diffusing material and reckons on balance opal perspex is best but the aim here really is to achieve even light which flash gives anyway. I've seen similar conclusions about on the web but just mentioning white plastic. The books were written when books were books and not full of that stuff that comes out of bulls at times and can smell rather a lot - just like the content of some modern books.

John
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[Geoff F]

It would be nice to be able to lose those over bright highlights but if they are there in 'real life' before you shoot . . .

Nowadays, I often reduce the problem with a little editing.

When I first got a modern flash unit I purchased a Stofen Diffuser, which worked well in those old flashes; but I couldn't get anywhere until I ditched it. Might still be in the back of my gear cupboard.

My best results, apart from those perfect light days, comes from using a couple of daylight quality 'studio lights' indoors.

Works fine for chilled moths placed on a natural background material but not so reliable for those quick moving flies which just want to get outside instead of posing for a few shots!