Ysarex Loc: St. Louis

No ND filter if you think about it -- it would show in the JPEGs.

Joe

Ysarex Loc: St. Louis

Wrong. I just proved that here:

https://www.uglyhedgehog.com/t-609317-13.html#10491484
https://www.uglyhedgehog.com/t-609317-13.html#10492475

That is most commonly correct but the ISO standard allows the camera manufacturers to do otherwise and there are cases where they do for good reason. The key to understanding that is founded on two points addressed in the standard. 1. ISO does not apply to raw files. The standard makes a point of spelling that out. I made the point way way back in this thread, https://www.uglyhedgehog.com/t-609317-3.html#10480581 that the ISO standard does not specify implementation by the camera. So the manufacturers are free to do as they please at the raw file level as long the correct output shows in the camera processed final image.

If you look at the examples I posted above the JPEGs are consistent with the ISO changes in compliance with the standard. And that's point number 2. The ISO standard applies to the camera generated final image. I also previously posted from this wiki article: https://en.wikipedia.org/wiki/Film_speed

"The Standard Output Sensitivity (SOS) technique, also new in the 2006 version of the standard, effectively specifies that the average level in the sRGB image must be 18% gray plus or minus 1/3 stop when the exposure is controlled by an automatic exposure control system calibrated per ISO 2721 and set to the EI with no exposure compensation. Because the output level is measured in the sRGB output from the camera, it is only applicable to sRGB images—typically JPEG—and not to output files in raw image format." [my bold]

The camera manufacturers (they wrote the standard) understand that as license to do anything they want under the hood as long as they keep the camera final output -- typically JPEG -- standard compliant. There are too many variations in what the camera manufacturers do under the hood then to permit defining ISO in terms of implementation with a blanket statement like "ISO is gain applied to the sensor signal." That's one way in which it is implemented but not the only way and that's not what it is.

Consider Sigma Foveon sensor cameras. At the same exposure they generate the same raw files regardless of the ISO setting. The camera simply records the ISO setting in the raw file metadata and the camera image processor takes full responsibility for implementation.

Joe

srt101fan

Depends on where along the in-camera signal processing steps the ISO amplification is applied? I don't know. And to add to all the things I don't understand, I read on anther thread that some cameras actually use a two-stage amplification!😢

The good news is that it probably doesn't matter....

Ysarex Loc: St. Louis

It might help if we don't call it amplification as connotations in that word can influence our thinking. If the ISO is raised above base the camera uses one or more of various methods to lighten the camera's final output image by the amount equivalent to the ISO increase.

From sensor exposure to final camera processed JPEG the camera manufacturers are free to amplify the sensor signal, and/or/or all digitally scale up the converted analog signal in the ADC and/or/or all lighten the image in the camera processing software. They can implement one, any combination of two or all three methods as long as they get the end result.

Joe

selmslie Loc: Fernandina Beach, FL, USA

Correct so long as you are above base ISO. I proved it with two different cameras and even Ysarex proved it with his last exhibit although he remains in denial. According to the POTUS, “And everybody knows that.” Well, almost everybody.

If that were not the case, how could ETTR work?

Ysarex Loc: St. Louis

I'm not the one in denial. You have been proven wrong:

https://www.uglyhedgehog.com/t-609317-13.html#10491484
https://www.uglyhedgehog.com/t-609317-13.html#10492475

That's hard proof and you have no rebuttal.

Joe

selmslie Loc: Fernandina Beach, FL, USA

You already proved that I am right at https://www.uglyhedgehog.com/t-609317-14.html#10493326

You just can’t believe your own eyes.

Ysarex Loc: St. Louis

That post shows that you were indeed previously proven wrong because it established the base ISO for the Canon G7xmkii.

This then proves you are wrong:

https://www.uglyhedgehog.com/t-609317-13.html#10491484
https://www.uglyhedgehog.com/t-609317-13.html#10492475

That's hard evidence and you have no rebuttal. Your juvenile behavior is just pathetic.

Joe

selmslie Loc: Fernandina Beach, FL, USA

Here is something interesting. Three images taken with the same exposure 1/30 sec @ f/2. The histograms seem to be the same.

But look at the image captions.

ISO 200

(Download)

ISO 640 with a polarizer over the lens

(Download)

ISO 1600 with the built-in 3x ND filter

(Download)

Ysarex Loc: St. Louis

But that doesn't explain what I did when I proved you wrong here:

https://www.uglyhedgehog.com/t-609317-13.html#10491484
https://www.uglyhedgehog.com/t-609317-13.html#10492475

Any filter changes would show in the camera JPEGs and my camera JPEGs are consistent with the ISO changes that were obviously applied by the cameras.

Joe

selmslie Loc: Fernandina Beach, FL, USA

Here are the SOOC JPEGs for the three shots. They are virtually identical. You are dead in the water. Keep grasping at straws. It's time you threw in the towel.

You really don't know what you are talking about.

ISO 200

(Download)

ISO 640 with a polarizer over the lens

(Download)

ISO 1600 with the built-in 3x ND filter

(Download)

Ysarex Loc: St. Louis

I wasn't talking about your camera JPEGs using the filters -- I was talking about the camera JPEGs from my examples that prove you are wrong:

https://www.uglyhedgehog.com/t-609317-13.html#10491484
https://www.uglyhedgehog.com/t-609317-13.html#10492475

If I had used a filter as you're trying to suggest then it would have altered my JPEGs as it did your JPEGs. My JPEGs show the ISO changes and so prove you are wrong.

Your lame attempt to try and claim I cheated doesn't work.

Joe

selmslie Loc: Fernandina Beach, FL, USA

If you think that anyone can see a difference in the light levels among any of the three JPEGs then you are truly delusional. You are lying to yourself - in denial.

The only one that might be slightly different is the ISO 640 with the polarizer if there happens to be any polarized light coming from the scene. And the filter factor might not be exactly 1.67 stops.

The only thing you have managed to prove is that you are stubbornly hanging on to a losing argument.

You still can't explain the two examples you posted where changing the ISO did not move the histograms. Anyone with experience shooting raw knows for certain that they should have moved. Your continued insistence that there is nothing wrong with them is making you look like a fool. You need to figure it out and then come back and apologize to us all.

Ysarex Loc: St. Louis

I don't think that and I didn't say that. I said the JPEGs from my examples that prove you are wrong do show the ISO change which proves I didn't cheat.

https://www.uglyhedgehog.com/t-609317-13.html#10491484
https://www.uglyhedgehog.com/t-609317-13.html#10492475

The Canon ones are below.



I most certainly can explain it and in fact I just did in a response to srt101fan. I can't explain it to you because you won't listen. And due to your juvenile behavior you don't deserve an explanation so you can just stay proven wrong.

Joe

ISO 125

(Download)

ISO 250

(Download)

selmslie Loc: Fernandina Beach, FL, USA

That pair of images proves exactly what I have been saying. That increasing the ISO moves the histogram to the right and also makes the JPEG brighter. See https://www.uglyhedgehog.com/t-609317-14.html#10493326 That's not the pair you need to explain.

Below is one of the pairs that looks screwy. The ISO doubled but the histogram barely moved although the JPEG brighter. Can you explain why it didn't behave like it did in your later example? Did the room get darker?

ISO 125

(Download)

ISO 250

(Download)