Shooting a different ISO than the film's ISO speed

Colibri

I've got a ISO 200 B&W roll of film in my SLR at the moment. What would hapen if I started shooting above 200 ISO? This really confuses me

Thanks guys and gals:)

hmboards

Is it an old manual SLR with a dial to set the ISO ? This is used to tell the camera's light meter what speed film you are using so that it can calculate the correct exposure. If you change the dial to ISO400 and you are using ISO200 film, then following the exposure meter will lead to underexposed images. For example it will suggest 1/125s when 1/60s would be correct. (exact number of stops my not be technically correct in my example but you get the idea...)

Colibri

Ah ****e. Thanks buddy

DaireQuinlan

Colibri wrote: »

I've got a ISO 200 B&W roll of film in my SLR at the moment. What would hapen if I started shooting above 200 ISO? This really confuses me

Thanks guys and gals:)

Short answer: It'll be underexposed.

Long answer: Most negative films can tolerate a fair amount of overexposure and somewhat less underexposure, in minimal cases probably without any real noticeable differances. B&W film is more tolerant than colour film. They can be pushed in development, ie developed at a higher temperature or for a longer time, to compensate for the underexposure, but at the cost generally of increased contrast and grain and detail free shadow areas and grainy midtones.
Different film and developer combinations can sometimes yield different apparent speeds as well. I shoot tri-x at 1600 for example (it's normally a 400 film) and develop in diafine for some lovely tones and gorgeous grain.

Fajitas!

hmboards wrote: »

Is it an old manual SLR with a dial to set the ISO ? This is used to tell the camera's light meter what speed film you are using so that it can calculate the correct exposure. If you change the dial to ISO400 and you are using ISO200 film, then following the exposure meter will lead to underexposed images. For example it will suggest 1/125s when 1/60s would be correct. (exact number of stops my not be technically correct in my example but you get the idea...)

Well, kind of.

You can push and pull film, you'll get more grain, more contrast, and somewhat less detail (all depending on what film). If you're developing yourself, look up the developing times for you film on The Big Dev Chart, and it should have details on how long extra you need to develop for.

If you're getting it done in a lab, most don't have the facilities to push and pull film, so you'll be better off doing it yourself if you can.

So... Google for 'pushing film' and add your film's name in after it, and see what comes up.

Fajitas!

Daire bet me to it :-/

mike65

Push - shoot at 400 have the film processed as a 200 and you'll get a more saturated image with grain.

Pull is the other way round, not as interesting to mess with though

sineadw

I shot some HP5 (400 B&W) last weekend, one roll at 400 and the other at 3200. I'll be developing them tomorrow, so I'll post a link to show what it does

Fajitas!

mike65 wrote: »

Pull is the other way round, not as interesting to mess with though

I usually do it to get more pastel-ey tones with Kodak Portra stock.