To show you this in action, here's a screenshot of the metadata browser for a library that has several of my recent jobs loaded into it. Some of these jobs, I shot alone. Others, I shot with Pinar Ozger, who has been working with me some this year. Looking at the browser, you can immediately tell a few things. First of all, my Canon 70-200mm f/2.8 IS USM lens is my absolute go to lens. If there is any one lens that is essential to my work, it's this one and the numbers back that up by showing that it's used for half the images taken. This tells me that if there's any single lens that I have to ensure is in working order, it's the 70-200. Second, if there's any piece of glass I can leave at home, it's my 20mm lens. I've not been happy with the image quality it produces and it shows in the usage numbers. I shouldn't even be lugging it around at this point and I should probably replace it with a lens that produces better results if I want to work at that focal length.

Another gem of information in this data centers on the two 300mm lenses in the listing. For the Web 2.0 Expo last month, I rented a Canon 300mm f/2.8 and put it to good use. It turned out to be such a sharp lens and worked so well, that I ended up buying the newer Image Stabilized version of it and using it at the MySQL Conference the next week for the bulk of the keynote shots. Even though I've only had it for a few weeks, it already accounts for a significant number of shots. I expect that soon, it'll be right up there with the 70-200mm lens as far as number of shots taken.

Unfortunately, the lens listings are only as good as the metadata that the cameras embed into the original files. For example, you can see that there are entries in the metadata tree for a EF 70-200mm f/2.8 IS USM lens and a 70.0-200.0mm lens. This is actually the same lens, but it shows up as two different entries because of the different amounts of metadata that various cameras embed. In this case, the Canon EOS 5D and 30D bodies embed enough data for Lightroom to call out the correct lens, but the Canon EOS 20D body on embeds enough data for Lightroom to show the focal length range. Even so, there's more than enough information here to sort out what's going on.

There's one thing that I wish I could do with this data that isn't currently possible. I'd like to be able to see an actual pattern of focal length usage in one place. Maybe something like a histogram display of the focal lengths used to create all of the images in my library. You see, now that I know that not only do I use my 70-200 a lot, but that it accounts for half of my shooting, I'd like to know at what focal lengths I'm really working. Am I spending a lot of time at 70 or 80mm? 135mm? Or all the way tight at 200? If I knew the answer to those questions, then I could target future lens aquisions appropriately.