Rich1939 Loc: Pike County Penna.

Larry, you ask much and many know little of the "how". Seems independent thought is on the endangered list as more and more simple decisions require group input.
Ya know, it really doesn't "take a village"

gtheodore Loc: Fort Collins CO

There is no ISO “organization” and you’re certainly not the first to think so. The fact that it’s capitalized leads one to believe its an acronym for an organization. The organization is the International Organization for Standardization. That might be IOS which means Apple’s screwed ;-)

Iso is a Greek word meaning “level with” (literally). So, from that we can expand it to “equal to”. And, we use that as a prefix to words like isosceles, isotope, isometric, etc. In Europe, many pronounce it “redo” - the Greek pronunciation of iso. So, ISO XXX means it’s equal to some standard imposed by the organization. This was pretty easy in film. Not so in the digital realm.

Note that many digital images carry the expression “ISO Equivalent”. So, it really isn’t a standard for digital imaging. And, given the complexity of a sensor it’s hard to imagine how one could “standardize” what iso, say 100, means. Does iso200 mean the exact same thing across all camera models? Is a camera base iso 200 more noisy than one that’s base 100? The “fake” annotation, I think, comes from the fact that in a digital camera, iso is applied after exposure by signal amplification and is determined by the camera manufacturer and not by an organization’s designation.

Bottom line is that iso in digital photography has a way different meaning than it had in film photography.

BebuLamar

DxO didn't say whether these cameras do or don't conform to the standard. I believe although they are different yet they are all conform to the standard.

Toby

I don't know this "Tony guy" but I know a little bit about ISO standards for other criteria and I trust the Institute much more than someone that's wants to see their name in print claiming something is a fact without objective scientific evidence

BebuLamar

check the ISO website and purchase the standard ISO 12233:2019 Photography -- Digital still cameras -- Determination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index. And tell me if there is no standard.

repleo Loc: Boston

Go to DxoMark and check the measurements of the various cameras in the compare section. Nearly all cameras have a difference between the camera's 'claimed' ISO and the measured ISO. The difference is usually at least 1/2 stop difference, but is consistant throughout the range of the camera except at ISO below the camera's base ISO.

BebuLamar

They are different but I believe they are all conform to the ISO standard. I don't say that they are not different I just said the standard is real and most cameras do conform to the standard although they are different.

Longshadow Loc: Audubon, PA, United States

burkphoto Loc: High Point, NC

Films were never consistent in their actual ISO speeds. When I used thousands of feet of Ektachrome, I had to test every new emulsion batch I bought for color balance and speed. There was plenty of variation.

Only a pro lab would notice the difference in batches of color neg film, though. It has a LOT of latitude.

Longshadow Loc: Audubon, PA, United States

I realize that there is SO many places, conditions, and information areas that can be really delved into very deeply. So glad I just have a camera and take pictures with it.

repleo Loc: Boston

Actually the ISO standard is ISO 12232:2019 Photography -- Digital still cameras -- Determination of exposure index, ISO speed ratings, standard output sensitivity, and recommended exposure index.

ISO 12233 specifies methods for measuring the resolution and the SFR of electronic still-picture cameras.

However, point taken. There is a standard. In all likleyhood, the standard allows a range of variance.

Dikdik Loc: Winnipeg, Canada

I first came across this concept about a month ago, and it 'sorta' makes sense.

Electronic 'stuff' happens somewhat quickly (aka approaching lightspeed) and there is very little delay. With regular film cameras, the effect on the film was chemical and noticeably slower. Special emulsions were developed to make film faster, but this was limited... it was not possible to have ASA speeds of 30,000.

With the faster electronic processing, the effect can be to generate more 'noise' which is what we observe. This will improve with time as we've noticed. Think of ISO as being an additional tool to use with your photographs. You can use fast ISO if you need it, but, there currently is a price. It's like faster or slower shutter speeds and smaller and larger apertures. The results can be used artistically and creatively to produce a more pleasing photograph. It is a lesser feature that the latitude of error is not as significant, and, may be improperly used as a marketing tool by some camera suppliers.

Dik

Longshadow Loc: Audubon, PA, United States

fetzler Loc: North West PA

In order to make a legitimate experiment in the comparison one would need to use a calibrated light source and/ or a calibrated light meter. Remember camera light meters may be off a bit. Furthermore the weighting method may differ between cameras. Tony's experiment, while interesting, is not fully scientific.

I seem to recall that the ASA standard referred to a certain film density being produced for a gray card. (I could be wrong) Film ASA was also variable as development times, choice of developer, and film batch. The gray (or gray scale) card test is at minimum necessary.

BebuLamar

While I didn't purchase the standard but I firmly believe that the standard allows for a variety of ways to determine the ISO rating and thus the variance we see among cameras and not because the camera manufacturers fake their ratings.