The location I was shooting at was at a local Metals Fabrication business near Denver. Locations like these are not unfamiliar to me. I've had to shoot in these sorts of location for years, and digital has certainly made shooting under these conditions much easier.
I had a detailed list of the images the client wanted for the article. They have done about 40 similar articles in the past and they knew exactly what they wanted in terms of images.
When I walked into the location where the milling machine was located, I noticed a large wall that was perfect for bouncing a strobe off of. I was able to produce a large light source from the surface I was bouncing off of. You can see the size of the bounce here in the photo below. You should also notice that I used a flag or gobo to prevent the light from directly striking my subjects. I want the main light to come from the bounce surface only.
The above bounce light was used specifically for the people shots I needed to do in addition to the type of photos shown at the top of the post. The light coming into this shot from camera right is the bounced light, camera white balance is set to florescent and the strobe was gelled with a +green to balance with the ambient light in the shop. The hard light you see on the subjects right side (camera left) is from a strobe positioned for the bit shot at the top of the post.
The photos of the actual milling process were handled a bit differently. I'm not really certain how fast the bit was turning, I knew that it was going to be the strobes that stopped the action. I lowered my ISO and set my sync speed to 1/250. I can't remember what power setting I had on the strobes (2 SB-800's) I set them as low as possible. The lower the power setting on a strobe the faster or the shorter the flash duration. With a short flash duration I am able to capture the small chucks of metal flying through the air.
I clamped to SB's to the milling machine, one of them with a full CTB gel over the flash head to provide a bit of color to the shot. Each strobe was clamped on either side of the machine, I also used some flags or gobo's to keep the light channeled where I wanted it.
Here are a series of images of the bit doing it's thing. Pretty cool to see the chunks of metal flying off the mill.
If your in the Denver area this Saturday, I'll be presenting a shorten version of my Small Strobes, Big Results workshop at "Denver Pro Photo". Just click on the link for more info.