The convenience and performance of digital has lead it to replace film in many areas. However film has some unique attributes which make it more suitable than digital in certain applications (by 'film' I'm including any light sensitive chemicals that can be used to form an image): Price - Whilst the price of digital has plummeted at the very bottom end, film cameras are cheaper to manufacture, which makes them suitable for disposable cameras, the type that are made of cardboard and shoot one roll of film which can't be replaced. ---------- Simplicity - A film camera requires as a minimum a light-tight box with a small hole. It is thus much more suitable for home-made cameras for either educational or recreational purposes. ---------- Low power - Film cameras can be entirely mechanical. This means they can operate on zero power making them suitable for cases where a camera must remain dormant for a very long time in an environment with no external power (e.g. a cave) before being activated by an external [mechanical] trigger. ---------- Long exposures - Digital camera sensors are active (consuming energy) the entire time during an exposure, and can heat up as a result. This energy use and quality lost due to thermal noise can place upper limits on exposure time. Film, whilst being suitable to reciprocity failure, is passive which means exposures can be much much longer, so for any applications which require very long exposures, such as solargraphs (where the exposure can be as much as a year) film may be preferable. ---------- Large format - Broadly speaking film costs increase linearly with area - if you want twice as much film it will cost twice as much. This is a simplification but contrasts strongly with digital sensors where the cost rises exponentially with sensor area. This is due to the way defects appear in the silicon. When making many small sensors from a wafer, a single defect could cause you to have to throw away one of the sensors, still leaving you with many viable units, however when making one large sensor, a single defect can cause the whole sensor being thrown away leaving you with nothing to show for your effort. To capture the highest levels of detail requires a physically larger lens and format, so for these applications film is either cheaper, or the only option. A good example is the GigaPxl project which captured images on film using a special camera that were scanned in at the resolution of a billion pixels.