Initially a pre-visualisation shot for an image I was capturing with my field camera. I wanted to check that my exposure was in the right region, slight variations between digital and film are always to be expected, especially in terms of ISO which is almost always less than what the film manufacturers state. Finding the right exposure values for the film I use and the the corresponding ISO on my digital camera will mean I have a great way of ensuring my exposures are where I want them. I think the 5D Mark II is fairly close to the Ilford FP4 125 at ISO 100, more testing is needed though.
If I go hiking for a few days into the Tasmanian Wilderness, I don’t think I want to be carrying the field camera with the film holders, film, lenses and the tripod and throw a 5D Mark II in for measuring light. Weight fast becomes an issue when out there, I think a light meter might have to go on the shopping list. I have found the Sekonic L-758D which is able to be calibrated to each camera and film type used, as well as dust and water resistance which is crucial in the Tasmanian Wilderness. A light meter is far smaller and more accurate with the ability to measure incident light as well as reflected light with a 1 degree spot meter. The Sekonic can also take multiple readings and average the exposure with the spot meter, a very handy feature considering I use the zone system when shooting with the field camera.