The Recent F/stop Controversy

Started 1 month ago | Discussions thread
tony field Forum Pro • Posts: 10,229
Re: Really?

Michael Fryd wrote:

Aaron801 wrote:

...

Good point! f-stop is useful for figuring out exposure, which is the same on any camera. You need to deal with exposure before anything else really, it's that basic. If you were say to have several cameras of different formats, the same rules of exposure would apply to each one and the same settings to get that same exposure. Sure, they will each handle noise differently, but that's not exposure and you don't really need ay kind of fancy jargon or a slide rule to figure that out. It's something that one can get a sense of when they use each camera. I have just one camera and I have a sense of how much noise I'm likely to get at any given ISO (which is also determined somewhat by light and subject)...

I disagree with your assertion that "You need to deal with exposure before anything else really, it's that basic".

That was true for film, but is not for digital.

If we assume we are using a camera with a light meter or equivalent, the very first thing we always did was choose the iso of the film to be used. This is established the exposure that would be considered appropriate. The only option for variable ISO was to have multiple cameras or multiple film backs with appropriate ISO selection in each.

In a sufficiently useful definition, ISO for digital and film is respectively the same: for a given light meter reading the output image should be brightened according to ISO standards to represent an 18% gray appropriately.

Why is it more important to deal with exposure before dealing with aperture or shutter speed? With film the answer was that if you didn't hit the target exposure that matched your film, nothing else mattered.

With digital, there is a wide range of exposures that produce good results.

For a given ISO or even auto ISO only a single exposure is appropriate.

The only real advantage of digital is that you have "many interchangeable backs of film" available in the digital camera firmware.

====

The other issue, is that with film, it's the light per unit area that affects your results. With digital it's the total light captured.

film systems responded the same way as total light on digital. You chose a larger format camera to achieve more total light or alter the ISO in your film holder.

With both film and digital systems, a single format camera only has limited ability to alter total light based upon ISO.

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Charles Darwin: "ignorance more frequently begets confidence than does knowledge."
tony
http://www.tphoto.ca

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