Film iso rating versus camera ability

[AlanKlein]

Derrel I'm stuck in the past. I still shoot Velvia 50 at ASA, ahem, ISO 50.

 

[dxqcanada]

When you have a camera film that says 800 to 3200 ISO, but your camera only goes up to 16-1800. Just what is going to happen when you use it, even at 16-1800 ISO for the cameras metering system?

There are some high speed B&W films, such as Ilford Delta 3200 and Kodak TMAX 3200, that are designed with a wide exposure latitude.
These films can be exposed at a wide ISO range ... if you set your camera ISO to something, then the film should be developed for that ISO.
example ... TMAX 3200 has a nominal speed of 800, and the development time could be 9min ... if you set your camera to 3200 ISO, then the film will need to be developed for a longer period of time, like 11.5min.

https://www.ilfordphoto.com/amfile/file/download/file/1913/product/682/
https://imaging.kodakalaris.com/sites/prod/files/files/products/F4001.pdf

 

[Soocom1]

Read this:

Film speed - Wikipedia

The 6400 speed film was a result of a change in ASA standards int he early 1960's.

I had vaguely remembered this issue from years ago and remember when some Kodak 6400 IR film had come out.

On older film cameras (pre 1965 or so) the high ISO speeds were used because you could push the development to allow a form of psudo push as it were by determining the f-stop and ev values.

But keep in mind that the higher the ASA/ISO ratings, so too does the camera's physical limitations on speed creep in. The single fastest shutter in the early 2000's was the Minolta Maxxum 7 and 9 with a shutter speed of around 1/8000. The film when rated to 3200 and 6400 has to be set down anyway because the shutters simply cannot move that fast.

This was also part in part to the Mirror Lock Up (MLU) system that crept out in the 1950's.

 

[webestang64]

FYI......the DX code on the T-Max and Delta 3200 is set at 3200.