On Jun 14, 2018, Jim-P wrote
(in article ):

On Thu, 14 Jun 2018 14:26:40 -0400, PeterN wrote:

On 6/14/2018 1:48 PM, Jim-P wrote:
In film cameras, ISO referrs to the sensitivity to light of the emulsion.
Manufacturers formulate different film emulsions with different
sensitivites tarding increased grain with increased ISO speed.

In a digital camera, presumably the sensor does not adjust itself to have
greater sensitivity. Or does it?

So what is happening in a digital camera when I choose a greater ISO
setting? Is more amplification being used?

I tried to understand this page but it got far too technical....

https://photography.tutsplus.com/art...ical-explorati
on--photo-11963

I am going to try to give you a simplified, non-technical explanation.
As with most generalities it is not 100% technically accurate, but
should serve as a guideline.
ISO is a measurement of the light sensitivity of the sensor. Digital ISO
is adjustable in many cameras. And yes, it is a matter of adjusting the
amplification. If you are using a wider lens opening, and slower shutter
speed, you will be able to use a lower ISO.
Digital noise is one of the undesired artifacts in the image. Higher ISO
will result in more digital noise, and lessor image quality. Many of the
newer high quality sensors are designed to work at a higher ISO, with
less noticeable noise, and reduction in image quality.
There are some of us here who do not object to noise, while others have
serious objections. The point at which noise becomes objectionable often
comes down to a matter of taste and personal preferences.

Thanks. This makes me wonder what ISO I should set, if I don't leave it on auto.

Let us start by asking, what camera are you using?

As far as which ISO you should use you should consider the light environment
of the scene you are trying to capture, along with your interpretation of
that scene, all balanced to achieve an acceptable exposure.

Auto ISO can work, but you are going to be better off if you have an
understanding of the exposure triangle and photography in general. It might
be time for you to read a book on photography.

Does ISO 200 on a digital camera broadly match the grain/noise of ISO 200
Fujicolor or Kodacolor that I used to use years ago?

Close enough.

Or do the ISO settings for a digital camera give quite different results to
the ISO values of film?

In a digital camera the ISO settings are going to be a close approximation of
ISO values of film, and are more guidelines rather than exact figures. For
example, you are going to find it difficult to dig up ISO 51200 film, but
there are digital cameras capable of producing acceptable images with ISO
that high.

--

Regards,
Savageduck