film Newbie question (apologies in advance)

[UltraDan]

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I shoot with an M4-p which. Has no light meter, can someone explain to me what is meant when people talk about shooting a film at other than its native iso? So for instance shooting portra 400 and somebody saying “ it’s great shot at iso 800” am I corrwct I’m thinking that it just means shooting at one stop over? I.e shutter speed 800 at desired aperture? Obviously on my eos 1 I can just set the iso to 200/800 instead of 400. 
 

or have I got this wrong? 
 

thanks,

 

dan 

[Pyrogallol]

No, that is right, it is just one stop over or under. Hopefully people who talk about taking pictures at other than the recommended ISO are talking from experience and for a good reason, don’t know why they say “native” must just be fashion or a new name for “normal”.

[ianman]

I suppose by "native speed" you mean "box speed" which is the recommended - as printed on the box, hence box speed - ISO to shoot the film at.

You have presumably heard about deliberately over or under exposing the film, which is different to  pushing or pulling the film. Pushing or pulling the film means to shoot AND process the film at a different (to box) ISO rating.

Personally I like to overexpose Portra 400. So I set the ISO on my MP to 200 and when I have it processed, I just ask the to do it at box speed. So they will process it as if I had shot it at 400.

For some black and white films, like Acros. I like to push it to 400, so although it's box speed is 100, I shoot it and process it at 400.

[pico]

Before one begins with a worry regarding perfect film exposure please consider that only YOUR experience is valid because of significant variations in individual components such as the light meter, shutter accuracy, the processor's competence and, of course, our own tendency to err in reading a meter. There is nothing as disappointing as to follow 'expert' recommendations only to find the 'expert' has a whacked-out system.

 

[jaapv]

It is not a bad idea to overexpose negative film by one stop and underexpose slide film by one stop in high-contrast situations. However, exposure as such is not simply following the meter. You need to judge which part of the image needs to be exposed to which density. There have been libraries filled by books on the subject, not in the least by Ansel Adams. I would advise you to study the subject.