USA Aloft uses digital cameras almost exclusively. Why? Film cameras are still best for some applications while digital images have their own set of advantages. Here are some of the things we considered. Pictures of Portland, Maine harbor are interspersed.
Volume of film. Probably the fundamental reason we chose digital involves the collection process itself. With our Firewire download to large disks we could make images every 10 seconds for several days. Even with a very large film canister, it would have been impossible to make multi-hour long flights while capturing images over the entire flight. The original image below was 7.5MB as a raw file.
Ease of Use. Digital images are more easily manipulated than film on a computer. Of course you could scan the film, but that costs as well, both in time and money. With digital, you have the electronic form immediately. It took about 15 minutes to create this entire sequence of images in which each successive image is blown up by a factor of 2. Traditional photographic techniques would have taken far longer.
Portland, Maine Harbor. 2X Zoom
Dynamic range. The digital images we capture are 12 bits per pixel per channel. Effectively this means the difference between the brightest possible pixel and the darkest is greater than what could be obtained with many films, particularly when you would need to scan the film to obtain a digital image. We have done no correction to this image, but we could easily tone down the bright areas or lighten the dark regions in shadow.
Portland, Maine Harbor. 4X and 8X Zoom
Cost is certainly a consideration, but perhaps not as much as you might guess. Certainly the film costs for the 50,000 or so pictures we have taken with our Kodak 760C Professional cameras would be significant, but there is a cost associated with taking digital images as well. Eventually, after many exposures, the CCDs used in digital cameras "wear out". The colors fade slightly after thousands of exposures. You can correct for this effect, but eventually the imaging chip must be replaced. We have estimated that including maintenance costs, it works out to about $0.16 to take an image. While this is certainly cheaper than film it is still not insignificant.
Portland, Maine Harbor. 16 and 32X Zoom
Resolution. The 3032 x 2008 resolution of the Kodak 760C approximates the resolution of many 35 mm films. Newer cameras, using CMOS technology approximate medium format film. So, today's digital cameras can produce images that are just as sharp as most film. If we were doing large format work, then film is still the only option. The rightmost image just below would have been about 24 pixels wide in the original image. We have none no digital sharpening, which is usually done to raw images when they are converted to jpegs. We also did no interpolation of the original pixels. Both of these techniques could be used to make the final blown up images "better".
Portland, Maine Harbor. 64X and 128X Zoom
Frame Rate. One area in which film cameras excel is speed. Our Kodak 760Cs have a burst rate of about 4.3 frames per second. But not for very long. Eventually the internal buffer fills up and the camera pauses until the initial internal processing clears the buffer. Digital cameras with large pixel arrays (and hence a lot of memory to move to store each image) all seem to suffer from this restriction. Film cameras on the other hand, especially those with motor driven advance and large film canisters, can take rapid fire pictures for long periods. For our aerial work, this restriction is not a problem.
Portland, Maine Harbor. Stereo Pair
As you view this stereo pair, realize that the detail shown above will be available when you zoom or pan the image in our stereo viewer.