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Looking for new diffusion materials
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Dalantech



Joined: 03 Aug 2008
Posts: 401

PostPosted: Wed Jan 31, 2018 2:54 am    Post subject: Looking for new diffusion materials Reply with quote

Hey folks,
For many, many, moons I've been using Gary Fong's Puffer Plus diffuser for my macro twin flash. Here's an explanation of how I use them. The surface of the plastic is dimpled, and it acts like a much larger diffusion surface. So I'm able to diffuse the light pretty well with a relatively small diffuser. Here's a worse case example (due to the working distance):



You can click on the image if you want to see the original. What I'm looking for is a similar diffusion material that's not curved like the Puffer Plus -heating that plastic up and trying to get it to lay flat has ended in disaster. Also any tips on forcing light to spread out in a small space would be appreciated. I like to shoot with one of the flash heads at the top of the lens (key) and the other to camera right (fill). The closer I can get those two flash heads the more control I have over shadows, and the specular highlights blend together so that it doesn't instantly look like two distinct light sources.

I've searched for a suitable replacement with no joy.
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ChrisR
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Joined: 14 Mar 2009
Posts: 7655
Location: Near London, UK

PostPosted: Wed Jan 31, 2018 6:15 pm    Post subject: Reply with quote

The sheets of clear and diffusing plastic used in backlighting of a flat screen (laptop etc) have "interesting" properties. (Not the polarizing sheets). I saw something about it but can't remember the details. They spread then align the light, or similar. They don't get damaged when someone cracks a screen, so a repair shop may source you one to play with.

I keep returning to tissue paper (like Kleenex) for good diffusion with low attenuation, but obviously you need something stiff.
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enricosavazzi



Joined: 21 Nov 2009
Posts: 957
Location: Stockholm, Sweden

PostPosted: Thu Feb 01, 2018 1:01 am    Post subject: Reply with quote

LED diffusers for interior illumination are another source of "exotic" diffusing materials. The most efficient are actually microlens sheets, with diffusion properties strictly controlled by the geometry of the microlenses. Diffusion in these materials can be made anisometric, e.g. a higher diffusion along a specific axis and a lower diffusion in a perpendicular axis.

I have seen one source of these materials making samples available (I don't recall the brand name), but it was not practical for me to order samples because they required a self-addressed padded envelope with postage stamps sent to them (and I have no way to buy US postage stamps in Sweden). Apparently they had never heard of Paypal, or did not want to bother spending time shipping small orders.

When found on the surplus market, plastic microlens sheets can be useful for experimenting. The supply of these materials is unfortunately only occasional, and the choice of types restricted.

Thin plastic Fresnel lenses designed for use as reading magnifiers are instead commonly available, and it may be worth testing their diffusing properties. Normally you can only find convergent lenses, but divergent ones (or a combination of two or more layers) might be more useful as diffusers.
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Last edited by enricosavazzi on Thu Feb 01, 2018 5:32 am; edited 1 time in total
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Dalantech



Joined: 03 Aug 2008
Posts: 401

PostPosted: Thu Feb 01, 2018 2:31 am    Post subject: Reply with quote

Thanks Chris and Enrico!

The down side to tissue paper, other than it's too fragile, is that it's also too smooth. That Puffer Plus plastic works well for a small diffuser because it's dimpled. Lot's of surface area. Even the Fresnel and LED diffuser plastics don't have the surface area, but if they transmit light really well I might be able to use one of them as a diffusion stage. In my experience using multiple layers of light diffusion works better than a single layer that's thick, space permitting. I'm really hoping to find a cheaper alternative than the Puffer.
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Dalantech



Joined: 03 Aug 2008
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PostPosted: Thu Feb 01, 2018 2:36 am    Post subject: Reply with quote

Wanted to add that I'm not unhappy with my lighting, but like most of you obsessed with making it better. For single frame macro I'm getting some really good detail with an MP-E 65mm stopped down to F11.

Newborn Blue Mason Bee V by John Kimbler, on Flickr

I'm making another pass at my lighting in preparation for shooting some limited stacking (maybe no more than 5 frames hand held). Gotta keep the duration of the flash as short as possible to help freeze motion though, so looking for materials that actually force the light to spread out and not just block it.
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ChrisR
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PostPosted: Thu Feb 01, 2018 7:17 am    Post subject: Reply with quote

Kitchen paper usually seems to be dimpled! Sure, studio only, I was thinking it might work if behind a clear front.

Big diverging fresnel lenses are used on vehicle rear windows to help parking. FL too long, probably. Confuses the heck out of schoolkids when they have one diverging and one magnifier - then they make an "Opera glass"....
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concon



Joined: 01 Jun 2017
Posts: 87

PostPosted: Thu Feb 01, 2018 8:36 am    Post subject: Reply with quote

https://www.rpcphotonics.com/

The above link has products that sounds similar to one of the comments in this thread- has anyone given something like this a shot? I'd hope that by spending something in this range that we'd see some really AMAZING diffusion.

My brain can't grasp really grasp what they offer yet, but I'm working my way through and googling each part I don't understand.


Edit-
Does look like they have a 50 dollar sheet option though. I might buy that to try out.
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Thu Feb 01, 2018 10:03 am    Post subject: Reply with quote

I've found the material that is used in the cheap eBay light tents the best for diffusion when attenuation is considered, this material is very good!! However it's has a cloth like texture and flexibility, so maybe not good for applications where some material stiffness is required.

A pair of light tents, one inside the other, separated by 6" or more is what I use when extreme diffusion & illumination uniformity is required.

Best,
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soldevilla



Joined: 16 Dec 2010
Posts: 491
Location: Barcelona, more or less

PostPosted: Thu Feb 01, 2018 10:03 am    Post subject: Reply with quote

The best diffuser I've tried (the only one I use, now) is the foam-type packaging sheet. I do not know exactly the English translation, but you can see it in the image of the link. It's very cheap, in fact they give me diffuser every time I buy something.

http://www.powerfull.es/galeria/6-foam3.JPG
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Dalantech



Joined: 03 Aug 2008
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PostPosted: Thu Feb 01, 2018 11:45 am    Post subject: Reply with quote

ChrisR wrote:
Big diverging fresnel lenses are used on vehicle rear windows to help parking. FL too long, probably. Confuses the heck out of schoolkids when they have one diverging and one magnifier - then they make an "Opera glass"....


I bought a replacement wide angle diffusion panel for a 600 EX RT, cut it in half, and was using it to disperse the MT-24EX. Did a pretty good job of knocking out the hot spot in the macro twin flash. But the MT-26EX RT has a better built in diffuser and doesn't seem to suffer from a hot spot.
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Dalantech



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PostPosted: Thu Feb 01, 2018 11:46 am    Post subject: Reply with quote

concon wrote:
https://www.rpcphotonics.com/


Too expensive for me -actually looking to cut some costs.
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Dalantech



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PostPosted: Thu Feb 01, 2018 11:48 am    Post subject: Reply with quote

mawyatt wrote:
A pair of light tents, one inside the other, separated by 6" or more is what I use when extreme diffusion & illumination uniformity is required.

Best,


I'm limited by the critters that I shoot, in the condition I want to shoot them.

Feeding Honeybee VIII by John Kimbler, on Flickr

Would love to use a light tent, but it's just not practical.
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Dalantech



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PostPosted: Thu Feb 01, 2018 11:49 am    Post subject: Reply with quote

soldevilla wrote:
The best diffuser I've tried (the only one I use, now) is the foam-type packaging sheet. I do not know exactly the English translation, but you can see it in the image of the link. It's very cheap, in fact they give me diffuser every time I buy something.

http://www.powerfull.es/galeria/6-foam3.JPG


I've tried similar materials but they either added an odd color cast to the light, or did a better job of blocking the light than actually forcing it to spread out. With my current diffuser I'm losing two stops compared to the bare flash.
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Thu Feb 01, 2018 12:19 pm    Post subject: Reply with quote

soldevilla wrote:
The best diffuser I've tried (the only one I use, now) is the foam-type packaging sheet. I do not know exactly the English translation, but you can see it in the image of the link. It's very cheap, in fact they give me diffuser every time I buy something.

http://www.powerfull.es/galeria/6-foam3.JPG


I also use the white somewhat dense packing foam, it's about 1/4" thick. I hang it on my strobes to help diffuse the light from the 7" diameter reflectors. I have a couple different types, and one type does have a slight yellowish color cast, the other is white.

Best,
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mawyatt



Joined: 22 Aug 2013
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PostPosted: Thu Feb 01, 2018 12:20 pm    Post subject: Reply with quote

Dalantech wrote:
mawyatt wrote:
A pair of light tents, one inside the other, separated by 6" or more is what I use when extreme diffusion & illumination uniformity is required.

Best,


I'm limited by the critters that I shoot, in the condition I want to shoot them.

Feeding Honeybee VIII by John Kimbler, on Flickr

Would love to use a light tent, but it's just not practical.


Just cut the material out and use it without the tent in a DIY fixture.
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