[pschlute]

Would you say then that the ASA data included with a photo is kind of useless since there is no standard used especially between manufacturers?

Although there is not one "standard" they all are within about 1 stop of each other.

Although I mentioned this before, it would be useful if not interesting to see images of say a standard image at various ASA settings

This is included in any comprehensive review of a new camera.

[wings]

Although there is not one "standard" they all are within about 1 stop of each other.

Okay thanks. How was that determined?

This is included in any comprehensive review of a new camera

That doesn’t really demonstrate a comparison or evaluation. An example that might help you understand would be when comparing computer monitors for color rendition if you are an artist or perhaps a photographer who wants one that displays colors as close to true colors as possible. I have done that. There are differences found in displays and some do a better job than others to show true colors, the standard.

[stevebrot]

That was an excellent reply. Would you say then that the ASA data included with a photo is kind of useless since there is no standard used especially between manufacturers?

There were ASA and are ISO standards for film sensitivity based on response above base fog. For Japanese-brand digital cameras, CIPA requires either of two standard methods, REI and SOS.* SOS is standards-based (18% gray card) while REI is the maker's recommendation based on their knowledge of sensor response. Some makers (Nikon are you listening) have been accused of fudging their low ISO, but overall consistency is good between brands with good agreement with external meters as well.


Steve

* The standard is available for download from CIPA.