question on camera film????

Question

in camera film ,it is specified as 400or200 or 100.
what does it means????

Answer 1

A lower number indicates that the film is "slower" meaning that it will a higher exposure time than film with a higher ISO rating.

Generally, 200 or so is normal and suitable for most purposes. If you are shooting a subject outdoors that moves quickly, like a sport event or an airshow, a higher ISO film will allow you to use faster shutter speeds which will reduce blurring.

If you want the highest possible image quality, a lower ISO will give you a finer "grain"

The difference is in the grain of the film, or the thickness of the emulsion. Finer grain will give you better quailty images. If you are planning to make large prints or prints suitable for framing, you will want the finest possible grain.

Answer 2

If you have a hand held light meter it is easier to figure out.

You don't need an expensive one.

Set the light meter for ISO 100 and see what the meter tells you what the exposure should be. Then do the same thing, measuring the same thing, but at 200 and then at 400.

Basically, it takes more light to correctly expose 100 then it does 200 or 400. I think also that if you measured the thickness of the emulsion on the film, there would be a higher thickness for 100 than 200 and even less at 400. This is what causes the grain.

In the best of circumstances, 100 film would give you the tightest grain and the best picture, but it would not be too much different from the 200, though it would have more grain - which might not mean anything unless you are going to enlarge the picture quite a bit.

If your light meter tells you that you should shoot at f5.6 and 1/125 of a second using the 100 film, keeping the same f stop, you should get the same results from a 200 film at 1/250th and with 400 film, you should get the same picture at 1/500th of a second with the same f stop. If you wanted to do the same thing leaving the camera at 1/125, you would shoot 100 film at f5.6, 200 film at f8 and 400 film at f11

In any instance, if you really want, or need, a good photo, regardless of what speed you are shooting -100, 200, 400, you should bracket your shots. To ensure that I get a good photo, I will shoot five shots of the same thing by either changing the shutter speed or the f stop.

My advice would be to get a roll of each type of film and waste some film figuring this out for your self. Keep a pocket spiral table in your pocket and each time you take a picture, put all of the specifics on that shot number. The best thing is to experiment.

Answer 3

That is the ISO or speed of the film. The 400 speed film needs a shorter exposure than the 200 speed film to take a picture of th same object.

Answer 4

Its the "ISO speed number" or just "speed" of the film.

A low number like ISO100 is a slow speed so it need more time and light to burn the image in the film. (Daylight or flash photography). This film is fine grain (films are made with light sensitive grains) so it gives the best quality and is good for enlargements.

Higher number ISO400 is faster and more light sensitive film, you can use less light but to get this faster film they use bigger grain on the film so it's not so good for large enlargements because you can see the grain texture.

ISO200 is something in the middle, it is faster than an ISO100 film and is less grainy than ISO400 film.

Answer 5

The asa/iso numbers represent the low light threshold at which that particular film produces a printable density on the film. IOO asa film take 2x as much light to produce a printable density on the negative as 200 asa film, 200 asa film takes 2X as much light as does 400asa film, 400 asa film takes 2X as much light as 800asa film etc...