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How should an exhibit be lit?

How should an exhibit be lit?

This is a development of an idea I had last year after reading a post by Christina on a visit to the National Museum in Copenhagen. In short most museums I go to seem to have much darker galleries for prehistoric material that classical material. That has to have a psychological effect, but does it also have a physiological effect? Is the difference in light enough that there’s a difference feeling to observing prehistoric material to classical material because of the room and not the content? You could also ask similar questions of European and Rest of the World exhibits. Are African exhibits in more dimly lit rooms, and if so what does this say about ‘world museums’.

It should be an easy enough question to answer; simply visit a range of museums in exotic locations with a light-meter and then number-crunch to find the answer. That’s not very efficient though. It means arranging permissions, travelling to the museums, and logging the data. It could take three or four days in terms of travel to some places to log 50 numbers. When it comes to number crunching more is better so is there a way round this? I suppose I could hire people to wander round museums for me with lightmeters, but that would be expensive and my bank is already experimenting with new shades of red to print my balance. It’d be handy if I could just find the data I want lying around the net somewhere. Regular readers will know I’ve been thinking about Flickr’s API a lot, and they won’t be surprised to hear that’s where I might have found the answer. A lot of people have been taking photos in museums and I think they could help.

It might sound bleeding obvious that all of Flickr’s photos were taken with a camera, but in the case of digital cameras Flickr can also store a lot more data. Attached to a lot of the photos is EXIF data. If you visit a photo like this one, you’ll see there’s a more properties link on the right side of the page. That takes you to a page like this one. It tells you the ISO setting, aperture and shutter speed for a photo. ((Usually – HDR photos won’t because the have multiple exposures)) If the camera is automatic then it will pick what it thinks are the best settings. The camera is set to manual, then the photographer is still probably going to choose what it thinks are the best settings. Therefore this gives a way to calculate relative changes in light.

For example ISO settings come from the days when people used film for photos. ISO 200 would react to light one ‘stop’ faster than ISO 100. ISO 400 was one stop faster than ISO 200 and two than ISO 100. So the ISO setting will let us calculate how many stops down the film speed is. The aperture is an odd scale because it relates to the size of the aperture of the lens relative to the focal length. But it can be calculated, f/22 is a stop up from  f/16 and f/11 is another stop down and so on. The same can be said for shutter speed You can go from 1/800 to 1/400 to 1/200 and so on.

Therefore, if you fix a datum you can measure how many stops up or down from that datum a photo is from the EXIF data. This is related to the light in the image and the camera lens looking into a gallery or display is a proxy for the human eye. It’s not perfect, you’d want a lot of photos but one thing Flickr has is a LOT of photos. It also has the API, which makes it very easy to transfer the relevant meta-data into a database for interrogation.

One reason I’m interested in doing this project is that I have no idea what the result would be. It could be emphatic, ambiguous or show that I have a very selective memory when it comes to lighting. It might sound obvious that you’d want to research something you don’t know the answer to, but to gain funding you have to show a likelihood of a positive outcome – or that the methodology is at least sound. I don’t know if this is the case, so the project won’t attract funding, but the API makes it cheap. Certainly cheaper than flying on budget airlines round Europe.

In terms of publication it seems like a good fit for Internet Archaeology. Internet Archaeology is moving in steps towards open access. Given the… umm… eccentric attitude the AHRC takes to digital media, and the current economic climate that’s a difficult move they’re making. The fact they are moving to Open Access makes it one of the most attractive venues to publish in academic archaeology. In this instance a database which can link back to the source files at Flickr would fit neatly into their hyperlink-friendly model. A bit of ingenuity with the SQL queries and database fields and it should be possible to make it a useful application for further research.

The biggest problem I see at the moment is whether or not estimating relative light levels from the ISO, aperture and shutter speed will be enough to distinguish between genuine differences in lighting. There are other non-trivial questions. If photos are of the exhibits rather than the galleries, then will the artificial light negate any measurable differences? It would certainly lose darkness in the peripheral vision. How do I gather the data? Can I pull it straight from the EXIF files from any photo on the site, but would this be reasonable if the photo itself is set to copyright? Would setting up a Flickr group for the project and trying to herd in volunteers, or sticking to CC licenced photos be better?

I think I could probably set up a small-scale test of this over the autumn and then take it from there, Still, it would be helpful if someone could spot all the flaws in this plan for me, rather than leaving me to stumble into them, so feel free to leave your comments below.