Film speed/b&w

[Silkfire]

Hi,

A question about film speed - in the FAQ sticky above it says ISO 400 film is one stop faster than ISO 200 - does that basically mean that, if a pic would have been properly exposed at f 8 1/90 at ISO 200, with ISO 400 it would be f 8 1/125 or f 11 1/90?

Does the camera automatically 'recognise' the faster speed or do you have to adjust some setting?



(by the way, thx to the people who responded to my nikon f55 query earlier!)

 

[santino]

that should be correct.

 

[ksmattfish]

if a pic would have been properly exposed at f 8 1/90 at ISO 200, with ISO 400 it would be f 8 1/125 or f 11 1/90?

You have it partly right...

If f/8 @ 1/90 is good for ISO 200, then the correct exposure for ISO 400 would be f/11 @ 1/90 or f/8 @ 1/180.

With shutter speeds the usual scale in full 1 stop increments is:

1, 1/2, 1/4, 1/8, 1/15, 1/30, 1/60, 1/125, 1/250, 1/500, 1/1000...

 

[ksmattfish]

Does the camera automatically 'recognise' the faster speed or do you have to adjust some setting?

Most modern film cameras can read the DX code (black and chrome) on the film cannister to get the ISO, and sets it automatically. With older cameras it had to be set manually.