technical: more sticks, screens and bulbs
April 22, 2008 – 5:00 amToday’s tech section is a chance to tie up some loose ends started over the last month or so. A little stick-in-a-can (from the DIY lighting videos) and a little bulb shootout follow up are on tap.
I’ve been promising stick-in-a-can and screen info and here it is:
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| The screens are made using 1″x2″ lumber. These are the kind of “L” brackets we use, along with the supplied screws. Always drill a pilot hold to thread the screws into when dealing with thin wood. As with all projects, find the straightest lumber you can. | Small but important tip: Affix the diffusion material to the front of the screen using white tape. If you use black tape it will be obvious in reflections (play “see the big black square reflected in the chrome toaster”). We’ve used clear packing tape but then the warm color of the wood reflects onto the set. Hmmm, we should be painting the wood white, too. You learn something new every day…. | In this profile you can see how the sticks are anchored to the edge of the can. In the videos I’ve mentioned how much more versatile this makes the stick-in-a-can, being able to clamp things to the very edge. Recognize all of the kinds of cans used (reuse, recycle)? Straight lumber is really important here. |
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| Vital: note the wood screws holding the stick in place. The paint can will need the top lip (where the lid goes on) cut away, then put the stick straight against the edge, drill a couple pilot holes and sink the screws. The concrete alone will NOT hold the sticks in forever. This will. And please don’t drop them onto the ground at an angle. if you dent the bottom of the can it won’t be flat and you’ll have a stick-in-a-wobbling-can. | A note about clamps. I like the old school metal ones on the left. The big chunky middle one relies a big rubber tip (nice in theory) but when that gets lost the clamping surface isn’t so great. Same with the over-thought design on the right. I hate these things. The little orange plastic tips flip all around and are never flat when they need to be. Buy the metal ones and be done. | Here it is, the diffusion material. Okay, so the project isn’t as cheap when you buy a nice big roll of 3008 Tough Frost 48″x 25′ (100 Sq. Foot Roll) Diffusion Material |
I had some great comments on the bulb shootout. The Reveal bulb held great promise but ended up being
disappointing in both color and quality of light. jlbec concluded “In other words, they’re for lighting your house, not your pictures :-)”. I literally laughed out loud. It’s worth mentioning that we use the Reveal bulbs (the frosted flavor, not the clear glass) in our digital darkroom / computer room and are happy with them.
NormMonkey pointed out that one of the stars of the test, the flourescent spiral, might have some unseen flaws: “One thing to note about fluorescent bulbs: they don’t create the full spectrum of light, the same way that a white-hot filament (or the sun) does”.
He suggested shooting a color chart so that’s just what I did. Small photos are below and you can get the full size charts by clicking on them. A quick look with the Info Dropper showed that the colors did respond a bit differently (reds were punchier with the tungsten) but nothing leapt out with the naked eye. If you plan to do any color-critical work (like reproducing artwork) then there might be a better choice than the fluorescents…but for most things you’re probably safe. If anyone out there wants to take the bulb-ball and run with it let me know what you find out, I’m definitely interested.
| Tungsten (100 watt GE Soft Light) | Fluorescent Spiral (nvision: daylight) 27 watt = 100 watt |
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Now let me spout a little tech junk about the above files: the photos were shot with a Canon 20D, RAW files converted in CS2 / ACR to sRGB with black levels at 5/5/5, mids 131/131/131 and white levels at 148/148/148, so, in theory, it should be pretty darn controlled for comparison.
Whew, that’s it for now. I do want to thank you for the great comments and suggestions. There will definitely be a white balance video coming up!
- Jim T.
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5 Responses to “technical: more sticks, screens and bulbs”
I agree with you about the clamps. The plastic ones are cumbersome to use.
By Jason Phillips on Apr 22, 2008
I loved the bulb shoot-out, and was very happy to see the results of the color charts! Have you had any experience with daylight balanced bulbs, like the trumpet-shaped ones:
http://store.tabletopstudio-store.com/lightbulbs.html
I’d be very curious to see what the color response of those bulbs is.
I only recently ran across those on this site about cheap studio lighting for quilt pictures:
http://www.hollyknott.com/stq/lighting.htm
(I must say, I like your stick in a can a lot more than their stick on four shelf-brackets)
By David on Apr 22, 2008
I’ll take a stab at exploring the realm of fluorescents vs. incandescents.
The GretagMacb… er, X-Rite, chart is on my wishlist but for now I found a shoebox at a friend’s house with a similar checkered colour pattern. While it’s no good for accurate colour profiling, I’ll try it for colour comparisons between bulbs.
Hopefully I won’t annoy mah hunnybear too much with random bulb scavenging around the house. I’m sure she’s used to my photography antics by now *grin*.
By NormMonkey on Apr 24, 2008
Norm,
please keep in mind, that the shoebox is printed using inks, that most likely suffer from metamerism. The perceived color of an metameric ink shifts radically with changing the temperature of the light source.
Thats why GM/X-rite and any other standart color charts are printed using special inks.
By n1x0n on Jul 12, 2008
This is one of the best sites I have ever found. Thanks!!! Very nice and informal. I enjoy being here.
By Yecuzas on Jul 29, 2008