Friday, January 25, 2008

Projected Backgrounds

I was looking to project a background for a project I was working on recently. For this particular project, I needed more light than the halogen in a slide projector could provide so an alternative was in order. After a little research I found the perfect solution to my problem, the Norman TL-2000 looked like just the ticket. After a quick look at the price tag, I suddenly found myself inspired to try a little DIY. So I called around to the local camera repair shop and found that they had a few broken slide projectors in the repair queue. After a conversation with the repair guy I came home with this beauty.

Now this projector is quite easily reparable (the ceramic bulb mount was cracked) which is why I was charged an exorbitant $60 for it but are we going to repair it? I thought not. Where's the fun in that?

I sat her down on my operating table and went to work. Looking in bulb compartment I found just the opportunity I was looking for. The light path comes straight to the back of the case where it is reflected off a mirror to the bulb which is mounted to the right. This means there are only two things in the way preventing me from pumping my own light in the back. First the easy one; the mirror comes out with just two screws. Next the back panel. I removed all 4 screws and took off the base plate. Then as I started working on the back panel I discovered that the little insert just pops out all on its own and, get this, the hole left behind is an almost perfect match for the lens in a speedlite. Coincidence? I think not. This mod was destined to be.
I popped out the insert and put the base plate back on. Finally there is one other parts we can remove. If you look at the optics in the body there are lenses just behind the slide mount. The first is a condenser; we want that. However the other is just a flat glass heat shield. Its important in close proximity to a halogen bulb, but when using a speedlite all it does is suck up light and add a greenish color cast so out it comes. Assembled again and back on her feet, you can see our leaner, meaner speedlite charged slide projector along with the removed parts and my sole instrument of torture.
Finally, some action. I used my 430EX (triggered by a Pocket Wizard) to project a photo of the moon on a white seamless. There is a softbox on the left spilling light on to my background which is hurting my contrast a bit but with better light control the contrast is great. Even without the heat shield the projector adds a bit of a greenish cast so white balance is a bit funky. Probably a pale windowpane green gel on the rest of your lights is in order. After a bunch of screwing around to get good focus I discovered that my little LED flashlight make a great modeling lamp.

Thursday, January 10, 2008

Why Strobes?

I received this question via Flickr mail (phrased somewhat differently) and I thought I would answer it here. Without question, strobes are difficult to use and many photographers shun them. They are expensive, hard to visualize and to the beginner metering strobes appears to be an arcane art. So why do we put up with them? Here’s a few reasons:

1. Power. They are the most powerful light sources available. Even small AA battery powered units can exceed the brightness of the sun at close range and high powered studio units can turn noon into midnight. A battery powered strobe can easily give you f/11 at ISO 100; with a comparable battery powered continuous light you are lucky to get f/2.8 at ISO 800.
2. Efficiency. High powered continuous lighting generates a lot of heat. High powered strobes can be used without the risk of fire or overheating your model.
3. Color. Strobes have a consistent color temperature near daylight resulting in lively full spectrum color in the final image.
4. Portability. The high energy efficiency of strobes means one (or several) small battery powered units can go with you anywhere.

I certainly spend many years as a photographer terrified of strobes. I had one, but the moment I put it in the hot shoe, I put the camera in full auto mode and hoped for the best. Today, though, with the instant feed back of digital cameras it is easier than is ever has been to learn how to use strobes. If you haven’t done so, pick up a strobe with manual power controls and take some time to play with it. There is no better way to learn than setting both your camera and strobe in full manual mode and experimenting. A little bit of reading and a few hours with the camera and the mysteries of the strobes will start to make sense.

To get started and an infinite amount of inspiration, here are some great resources:

Strobist 101
EOS Flash
Light, Science and Magic
Master Lighting Guide for Portrait Photographers