Tuesday, February 26, 2008

Softbox


Loneliness
1/4sec (from van window!) F2.8 iso200


Secondly, a photo of a finished scone, for those who were curious! Sorry, its the best I have right now. Take it from me though, they do look great.


Although I wanted to start this post with a good photo, the rest of it is going to be about the DIY softbox I am in the process of making.

I ran through a variety of ideas for making this softbox but this is what actually happened! For holding the bulbs, cheap standard screw-type light bulb bases (with pull chains to turn them on/off if it will be necessary to lessen the amount of light - the spiral CFL's I am using are not dimmable). For mounting them to, a piece of plywood. I had originally envisioned a rectangular arrangement of 2x3 bulbs but while fiddling with arranging them came up with the idea of a circular pattern. This has proved really easy with the exception of the reflector - I'll get to that.

While making the pattern for the circle I went ahead and drew in the circles for locating the centers of the light bulb bases (I knew I would need to drill a hole behind them to wire them) and the mounting hole locations for the bases (to make centering the bases over the holes really simple). Drawing these was really simple using some wire mesh I found - I just measured the appropriate distance and used it for a compass (see photo). The wood circle is 16" d. The wood is 1/2 ply, a scrap I had around from another project.


I drilled the wiring holes with a 2 1/8 holesaw bit, a size I happened to have. A little larger would have made the wiring easier. I cut the circle with a bandsaw set for 45 degrees - for the reflector. A jigsaw would be another good option.

Here's the finished wood - base mounting screws in place:

Wiring was done using 12 gauge THHN copper - white is neutral, black hot. I ran a bare copper wire for ground out to the front of the fixtures - somewhat unnecessarily but the cord I was using did have a ground and I figured it could ground the aluminum foil I planned on covering the front of the wood with! The bases are wired in parallel.

The bases in place:
For the reflector I used some stuff with a brand name of "reflectix" - it is an insulating material available at my local building store. Basically bubble wrap with silver foil either side. I chose this because it is very reflective and also has some rigidity of its own. It comes in rolls - I bought 25' 16" wide.


At this point a square design would have paid off - I wanted the reflector at approximately 45 degrees to the wood base. To do this I had to fold it at various points around the circle. To make it simple I measured 6" intervals along one edge of the roll, then every 6"I folded the next 6" length and stapled the edge together. The photo will explain this better. Later I taped each fold with real aluminum duct tape (rather than the redneck variety this is really made of aluminum and is really shiny!). Although these "ribs" were a pain to make they do add a bit to the stiffness of the whole.

I didn't calculate the needed circumference but simply made as many of these "gathers" as I needed, stapling the reflector to the wood circle as I went - which if you remember already had a 45 edge which helped the whole effect.

Final touches - some white sheet material over the front to diffuse the light. (It was interesting to see the multi-shadow effect that using this light bare gave.)

Since these photos I have modified the design to make it more portable. I pulled out the staples holding the reflector to the wood base, and replaced them with sticky-backed velcro, the hook side stapled to the wood, the loop side stuck to the inside of the reflector. Where I had taped the two ends of the piece of reflectix together I replaced the tape with another velcro connection - this was the whole reflector comes off and can be rolled up.

Things for the future of this light:

- An elastic edge to the white sheet to hold it nicely on the reflector.
- Backing, with mounting system of some kind, to go behind the wood and cover up the wires.
- Possibly a fan, or vent holes somewhere? The lights get fairly hot in the enclosure. No where near as hot as incandescents, but then I'm not sure how hot these CFL's run well at...?

I've included some example shots made using this light. I have noticed that many people who make DIY lights / flash modifiers end their post with some quick fashion shots of some of the hot models who apparently hang out around photographers :) As for myself, I could only get one model to sit for me...

...How do you like the studio?

You can see the catch lights in this one:


1/38 sec - F3.2 - iso400

...Both are shot in iso400... On the day I can use iso800 in a pinch, having a better camera. I needed iso400 to get the shutter speed in the handheld range. There was no other light in the room for these photos & no flash used.

Conclusions:
- I need to experiment more.
- I'm pleased with the quality and quantity of the light, and the nice soft shadows it produces.

3 comments:

udijw said...

Great work, Jonathan.
It is the perfect combination between a ring light and a softbox.
I love the reflector you put in there.
- udi

apmgold said...

Nice job Jonathan.
May I ask what is the spec of the cfl's used, ie. wattage colour etc.
Keep up the great work.
Mac

Jon.B said...

These are Home Depot 100W spirals - the brand is N:vision. They are 6500K I think but will check again for you. They don't say that on the package but just "daylight".

I chose these bulbs as a starting point figuring I could always upgrade to something more professional. They have good reviews several places on the net. I "heard" that the CRI was about 92 but they don't make any claims. I'm pretty happy with them so far. I will post some more results later.