DIY diffusion panels - avoiding color cast

[feppe]

Instead of spending well over a 1000 EUR/USD on ready-made diffusion/reflection panels which don't even fold up for air travel, I'm considering building my own panels out of PVC pipe and fabric for a fraction of the cost. I'm planning white fabric with enough translucency for shoot-through and reflector, thick black for gobo, and silver if I can find good fabric.

What should I look for in white translucent fabric to minimize color cast when using as a diffuser or reflector with strobes? Any easy way to check for neutral white in a fabric store with fluorescent lighting? If not, how would I go about checking which fabric is most neutral if I bring test patches home to test? Do I just light them with strobes to gray card gray, shoot RAW, and see which one is most neutral? What about silver?

[Sheldon N]

I've tried the fabric store option, and it was okay. However like you said the fabric I chose (sports ripstop nylon)ended up having a bit of a color cast and was not as diffuse as I had hoped when shooting with strobes. It showed some of the point source of the strobe head through the fabric rather than totally diffusing the light.

I've since gone and bought nicer thin weight (0.75) ripstop nylon from a kite building store to use as diffusion material. It was more neutral and has better diffusion properties.  I think I bought it from here...

www.kitebuilder.com

[alain]

I've tried the fabric store option, and it was okay. However like you said the fabric I chose (sports ripstop nylon)ended up having a bit of a color cast and was not as diffuse as I had hoped when shooting with strobes. It showed some of the point source of the strobe head through the fabric rather than totally diffusing the light.

I've since gone and bought nicer thin weight (0.75) ripstop nylon from a kite building store to use as diffusion material. It was more neutral and has better diffusion properties.  I think I bought it from here...

www.kitebuilder.com

Also used a ripstop nylon from a kite building shop : Chicara: 155cm width, weight 42gr/m²,  a few years back : 9.25 euro/m
I had it tested and the results where quite good colour wise.

[RFPhotography]

Pick up an XRite Color Checker Passport and you don't need to worry about the fabric and any colour cast.  Terrific little device.

[feppe]

Pick up an XRite Color Checker Passport and you don't need to worry about the fabric and any colour cast.  Terrific little device.

Have one already. Would like to get everything right in-camera in the studio, though, especially when shooting film.

Thanks for the kite building shops tip, I'll check if there's such a thing in Amsterdam.

[alain]

Have one already. Would like to get everything right in-camera in the studio, though, especially when shooting film.

Thanks for the kite building shops tip, I'll check if there's such a thing in Amsterdam.

Look for "vliegerwinkel" or "vlieger", I expect that there a few shops. 

[Dustbak]

You can also buy the fabric from California Sunbounce on a roll. Probably comes at a premium but would be interesting to find it when compared to material with the same characteristics?

[elf]

I'm using rip-stop nylon from a fabric store.  It's only a couple of dollars a yard, so I'd suggest just picking some up and testing it in your studio.  If you design your panels to hold multiple layers of fabric, you should be able to control hot spots and the amount of diffusion.

[feppe]

You can also buy the fabric from California Sunbounce on a roll. Probably comes at a premium but would be interesting to find it when compared to material with the same characteristics?

Seems to sell with 25 square meter minimum purchase (which is over twice the area I need) for well over 300 EUR (plus shipping), which I guesstimate is more than the entire cost of four 2x1m DIY panels built from normal fabric. Similar pricing on B&H for diffusion materials sold by the roll. Talk about photographer premium...

I'll check fabric and kite stores and get some samples.

[alain]

Seems to sell with 25 square meter minimum purchase (which is over twice the area I need) for well over 300 EUR (plus shipping), which I guesstimate is more than the entire cost of four 2x1m DIY panels built from normal fabric. Similar pricing on B&H for diffusion materials sold by the roll. Talk about photographer premium...

I'll check fabric and kite stores and get some samples.

Is there a reason for the 2 by 1 meter?

[feppe]

Is there a reason for the 2 by 1 meter?

Not particularly. 2 meters should be good for full-length portraits, and 1 meter is half of that - makes for standardized ~1-meter sections whch are easy to fit in an airline-friendly bag when taken apart. The idea is to make them into v-flats mainly as reflectors (black or white). Still figuring out the best way to do that, A-clamps seem to be a good quick option, if bulky and heavy.

I'm also planning to make a few 1x1 and perhaps even smaller ones, mainly for flags.

[UlfKrentz]

Hi Feppe,

Frames are in common use in the motion business. I´d suggest to make a size of 6x6 or 8x8ft, as this is a standard frame size and you could always rent fabrics you don´t own. We use Avenger frames (e.g. H2008 or H2508) which fold up very easy and are extremely firm, but you may find them a bit pricey and to heavy to fly with them.
There are plenty of different fabrics, some of them will be difficult to get in a standard fabric store. Take a look at: Quarter stop, china silk, quarter grid, full stop for diffusion and silver/white for reflection, you can also use them in combination, may be you rent a set first and work with the different types to get an idea what to look for. I don´t think these butterfly textiles are overpriced, they are very well made, equipped with eyelets, rubber strips and delivered in a bag. If you buy anything elsewhere be careful with cold white colors.

Cheers, Ulf

[feppe]

Hi Feppe,

Frames are in common use in the motion business. I´d suggest to make a size of 6x6 or 8x8ft, as this is a standard frame size and you could always rent fabrics you don´t own. We use Avenger frames (e.g. H2008 or H2508) which fold up very easy and are extremely firm, but you may find them a bit pricey and to heavy to fly with them.
There are plenty of different fabrics, some of them will be difficult to get in a standard fabric store. Take a look at: Quarter stop, china silk, quarter grid, full stop for diffusion and silver/white for reflection, you can also use them in combination, may be you rent a set first and work with the different types to get an idea what to look for. I don´t think these butterfly textiles are overpriced, they are very well made, equipped with eyelets, rubber strips and delivered in a bag. If you buy anything elsewhere be careful with cold white colors.

Cheers, Ulf

Thanks for the tips. I think the biggest challenge will be finding a good fabric. I'm visiting B&H in a few weeks so I'll try to procure good fabric locally (Netherlands) before that, otherwise I'll have to bite the bullet and pick a roll or cut sheets from there.

[Lightbox]

I've just about finished making my DIY diffusion panel, I decided to go with an aluminium frame as my local 2nd hand hardware store had a square profiled tubing and 90 degree right angle joiners for cheap, these were originally designed for making DIY coffee tables but were perfect for a panel frame. I went with a 2.3m x 1.3m size to start with as the 2.3m length just fits in my car, had a few different ideas on how to connect the fabric to the frame and decided on snap lock buttons as they are quick and easy to fix to both the frame & fabric when making the panel and also quick to setup on location. I plan to make 3-4 different fabrics, the first one I've made is Frost Cloth that you use for covering plants in winter, not quite translucent and perhaps cuts 2/3 of a stop of light. Haven't had a chance to go to the city yet but I'll get some nylon ripstop and also a nice black mesh. Here's some pics -










I looked at a lot of the commercial solutions to connect the frame to a light stand and didn't find one I liked, and being a DIY project I wanted to keep true to that. I already had 2 plastic boom knuckles that I use to hold small reflectors so decided to mod these to clamp onto the frame which makes it easy to change the frame angle at anytime and use it horizontal as well. They aren't quite finished in the photos above but basically you have two aluminium nuts welded to the aluminium U frame, on the opposite side a bolt goes through the U and through the panel frame and tightens into the nut. This creates a solid connection giving the frame no way of torsional twisting or slipping.

Next its back to the sewing machine to stitch up some more fabrics for the frame, then get out and start shooting with it...

[feppe]

Looks really good. The cloth seems very light, might produce hotspots unless you have a second diffuser (ie. softbox). Have you tested it out?

Also, wouldn't a pair of A-clips be enough to hold the stands? I'm going for the v-flat route to avoid having to dedicate a light stand to erect the panels, but might need another solution when traveling as twice the # of stands will take a lot of space. Are you using a full-height light stand? I'm thinking a short backlight light stand should be plenty, as clamping at around 1/3 of the height of the panel should be enough indoors.

[Lightbox]

Haven't had a chance to shoot with it yet, and that frost cloth is really light I thought it would be good to block full sunlight yet still letting enough fill light through, or as a cover for a window when shooting an interior shot. I will sew up two more fabrics that are more opaque and balanced but I haven't bought these yet. As mentioned above the kite making fabric seems ideal and pretty robust too.

Both stands I'm using for this are big steel stands that top out at 3.8m, although the boom knuckle can clamp onto smaller lighter weight stands. I do imagine using it not only as a vertical panel but to have it elevated and set horizontally to either block overhead light or to create it. That's why I built the boom knuckles into clamps, otherwise two A clamps would do the job for holding the panel vertically with just one stand. Requiring two stands just for the panel does add to the gear list which might be an issue for deep locations but that's what assistants are for right

[Jonathan Ratzlaff]

I used 3/4" pvc pipe and fittings for diffusion panels.  Reasonably light and sturdy.  Pipe comes in 10 or 20 foot lengths, makes a 6'6X3'6" panel frame using 90's.  Glue the 90's into the shorter pieces.  I guess if you wanted to shorten the long pieces you could put a coupling in the pipe, however the frame may be less stable.  If you want legs, use a T for the bottom frame and then make legs out of pipe as well.  If you sew a piece of elastic in each corner of the fabric panel you can easily break the system down.

I got the idea from Montizambert Photography in Vancouver and it works very well.  They used white rip stop nylon for diffusion panels, coated for reflectors and other fabrics as well. 
Frame should cost less than $20.