MadSci Network: Chemistry

Re: Is it possible to ruin film (35 mm) while still in the camara?

Date: Thu Jun 26 05:06:48 2003
Posted By: Gareth Evans, Industrial R&D practitioner and manager ( retired )
Area of science: Chemistry
ID: 1055169766.Ch

Hello Cindy. Your question was “Is it possible to ruin film (35 mm) while still in the camera?”.

Unfortunately for all photographers the answer is “Yes” and you made a number of good suggestions as to how this could happen. The good news is this is rare and normally, films still give great results despite their vulnerability under some circumstances. Cameras are designed to keep out light except when capturing a scene. Light can only reach the film if it bounces off several black surfaces and this is normally quite sufficient protection. You mentioned taking a picture of the sun and wondered whether that could ruin the film. Certainly, without special filtration that is a bad idea. The internal surfaces of cameras are nominally black, that is they should not reflect any light, but in reality some light is always reflected or scattered from the surfaces. With an especially bright light such as direct sunlight it may well cause some of the film to be affected apart from the frame being exposed.

You also mentioned taking pictures of magnetic objects. Although there are some processes in the recording of images which could theoretically be influenced by magnetic fields, these have to be enormous and it is highly unlikely that magnetic objects will cause any noticeable effects. The only exception to this is in the Advanced Photographic System ( APS ) films where a magnetic coating on the back of the film is used to write information to enable a number of extra features in cameras and printing systems. This coating, like audio tapes or floppy disks, could be ruined by being too close to magnets, for example un-shielded loudspeaker magnets.

Another potential problem is from ionizing radiation. You mentioned security systems at airports. These use X-rays, very energetic electromagnetic waves which can penetrate camera bodies and film cassettes and expose films. Normally the amounts of exposure are very small and you will see no noticeable effects. However, in general, the more sensitive a film is to light, the more sensitive it will be to X-rays. I usually use ASA200 films or slower to be on the safe side when traveling. With increased security measures these days some damage is becoming more likely. There are also several sources of natural background radiation including cosmic rays. These all contribute to the slow loss of performance of films due to a build-up of the effects of this radiation, namely “fog” or minimum image density and “grain” or non-image density variation.

The other enemy you mention is chemicals. Certainly chemicals can ruin film but within a camera or cassette in is unlikely that you will see any problems. Formaldehyde, ozone and hydrogen peroxide are some of the most likely culprits but films are less prone to attack by these chemicals than they used to be due to improved chemical components in the films.

The biggest cause of ruined films is one you didn’t mention. Heat. It is so easy to leave a camera in a car in the sun and the temperature can reach levels where film is ruined in hours. Always keep your camera out of direct sunlight, not because the light might get in but because it will get hot, especially if it is black on the outside. Another tip is to keep your films in the ‘fridge but when you want to use them let them warm up before you unpack them. This will stop the film surface attracting condensation.

Best of luck with your project and your photography.

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