DIY diffuser test shot

I made a DIY diffuser along the lines of Brian/Lord V's soda can diffuser, with some variances. My flash is still camera mounted, so I needed a diffuser that was longer, and angled down. I also wanted to have a larger light source in front, so I used a 2 liter soda bottle. I roughly followed Brian's design, making changes to accomodate my needs. I lined it with aluminium foil (shiny side out) and have the paper towel diffusion panel. The paper towel looked pretty fragile, so I put a thin layer of translucent plastic (aka Wal-Mart bag) over it.

Seems to work pretty good:

Very nice. How about a pic showing the diffuser if you can

Alistair.

Diffuser Pics. Can't show you on-camera as I only have my 30D. At first, the top of the panel was being lit more than the bottom because it is almost a straight from the flash unit. I solved this by opening the diffusion panel on my 430EX before sliding the Diy version on. This spread the light evenly across the inside of the diffuser, and I'm losing no light because the inside is lined with shiny side of aluminium foil. Now the panel is fully lit.

What about using the plastic from a milk jug instead of a paper towel? You're losing a lot of light with the towel in front even with all the aluminum inside the bottle...

One way to get a feel for how much light is being lost: Take a shot without the diffuser and notice how long it takes for the flash to charge up for the next shot. Then take a shot with the diffuser and see how long it takes the flash to charge again. It should be almost instantaneous with and without the diffuser unless the diffuser is blocking too much light.

Why is it important: The intensity of the light that a flash produces is always the same no matter what the exposure. But the length of time that the flash turns on (the flash duration) does change from exposure to exposure. For macro photography you need to keep that flash duration as short as possible, since it is your real shutter speed ( a more detailed explanation here ) and you need it to be as fast as possible to freeze motion -your motion and the motion of your subject. It doesn't matter if you hand hold or use a tripod you still need that flash duration to be as short as possible.

The longer the duration of the flash the longer it takes for your flash unit to recharge for the next shot...

Good shot- looks like the diffuser is working . I don't worry about the front paper towel being fragile as I stick it on with a few pieces of sellotape afterwards. The sellotape can easily be peeled off the duct tape so the towel is easy to replace.

John- not sure about this model but the coke-can diffuser I use with paper towel is highly light efficient. I can normally get 5 or 6 shots off without the 430Ex apparently recharging at all - I need this for doing rapid shots for focus stacking.

Brian V.

Dalantech wrote in post #3953365
What about using the plastic from a milk jug instead of a paper towel? You're losing a lot of light with the towel in front even with all the aluminum inside the bottle...

One way to get a feel for how much light is being lost: Take a shot without the diffuser and notice how long it takes for the flash to charge up for the next shot. Then take a shot with the diffuser and see how long it takes the flash to charge again. It should be almost instantaneous with and without the diffuser unless the diffuser is blocking too much light.

Why is it important: The intensity of the light that a flash produces is always the same no matter what the exposure. But the length of time that the flash turns on (the flash duration) does change from exposure to exposure. For macro photography you need to keep that flash duration as short as possible, since it is your real shutter speed ( a more detailed explanation here ) and you need it to be as fast as possible to freeze motion -your motion and the motion of your subject. It doesn't matter if you hand hold or use a tripod you still need that flash duration to be as short as possible.

The longer the duration of the flash the longer it takes for your flash unit to recharge for the next shot...

Thanks for the info. I made this as an alternative to what I did have, THIS. It wasn't soft enough, since the light was so far away, and it DID have a long recharge time. I saw LordV's design (and his photos taken with it), so I decided to work with that. The recharge times have been very fast, faster than I thought they would be.

LordV wrote in post #3953617
Good shot- looks like the diffuser is working . I don't worry about the front paper towel being fragile as I stick it on with a few pieces of sellotape afterwards. The sellotape can easily be peeled off the duct tape so the towel is easy to replace.

John- not sure about this model but the coke-can diffuser I use with paper towel is highly light efficient. I can normally get 5 or 6 shots off without the 430Ex apparently recharging at all - I need this for doing rapid shots for focus stacking.

Brian V.

Thanks, Brian. Like I said earlier, I have no noticeable recharge time, either. Thanks for the inspiration.