Need help with exposure question

[Ysarex]

@Ysarex

Make sure to include the histogram for each before and after

Sent from my SM-J737T using Tapatalk

I posted two photos for you earlier that met your criterion and used my Canon G7 which is surprisingly ISO invariant for a little compact. I think they're adequate and refute your assertion but just in case you want to get super fussy as there are some subtle differences I went ahead and hauled my XT-2 out of the closet. The XT-2 is considerably more ISO invariant than the G7 -- in fact for all practical purposes it is fully ISO invariant. Just so you have no wiggle room whatsoever, here's proof you were talkin' nonsense. EXIF data is in place so you can check them. I'm going to post them with links so you can have them at full res and can pixel peep your eyes out if you like. NOTE: I also went ahead and shot a very high contrast scene this time so it pushes limits.

The two histograms:

I don't believe there's any reason to note which one is which.

First photo ISO 100, exposure at f/10 1/2 sec.: ISO_100_xt2.jpg
Second photo ISO 800, exposure at f/10 1/2 sec.: ISO_800_xt2.jpg

Joe

 

[AlanKlein]

I never even HEARD of the so-called exposure triangle until well after the year 2000. Seriously. I learned that exposure was Intensity x Duration, with Intensity including the lens f/stop and the brightness level of the light, and duration being shutter-open time. I. Never. Ever. Heard. Of. The. Exposure. Triangle. Until.The Web.Era.

...

The reason it seemed like you never dealt with triangles before 2000, is because you shot film. With film, you were stuck with the ASA now called ISO of the film. Once in the camera, there is no way to adjust the speed ISO of a specific film except for pushing and pulling. If you always shot the same type if film, you never had to change the ASA selection in your might meter. With digital, the camera has the ability to change the speed of the film now called the digital sensor. That third selection created the triangle. Being able to change the ASA of the camera so easily, made the third selection so omnipresent. Of course, even with film, you had to enter the ASA/ISO of the film to determine the shutter speed and aperture. If you change the film speed, then you had to adjust that variable in the light meter as well just as you do in a camera. So even then you dealt with three variables.

 

[Ysarex]

I never even HEARD of the so-called exposure triangle until well after the year 2000. Seriously. I learned that exposure was Intensity x Duration, with Intensity including the lens f/stop and the brightness level of the light, and duration being shutter-open time. I. Never. Ever. Heard. Of. The. Exposure. Triangle. Until.The Web.Era.

...

The reason it seemed like you never dealt with triangles before 2000, is because you shot film. With film, you were stuck with the ASA now called ISO of the film. Once in the camera, there is no way to adjust the speed ISO of a specific film except for pushing and pulling. If you always shot the same type if film, you never had to change the ASA selection in your might meter. With digital, the camera has the ability to change the speed of the film now called the digital sensor. That third selection created the triangle. Being able to change the ASA of the camera so easily, made the third selection so omnipresent. Of course, even with film, you had to enter the ASA/ISO of the film to determine the shutter speed and aperture. If you change the film speed, then you had to adjust that variable in the light meter as well just as you do in a camera. So even then you dealt with three variables.

Been here, done this. From post #32 in this thread in response to AlanKlein: "ISO is important -- never said it wasn't. Above I just confirmed it's needed to get a proper exposure. The problem shows up when you change ISO's roll and try to turn it into an exposure determinant. Read the water faucet analogy in my last post."

From post #31 in this thread in response to WayneF: "You're going to turn on the water and fill a beaker (ISO). You have constant water pressure at the time (scene luminance). The faucet handle is a little special and is equipped with click stops so that you can open it one, two, three, four, etc. clicks and each click opens the value more (aperture). You take an 8 ounce beaker and hold it under the faucet and open it two clicks for 5 seconds (time - shutter speed). The beaker nearly fills. Congratulations! Set that aside. Now reach up on the shelf and grab a 16 ounce beaker. Hold the 16 ounce beaker under the faucet and open it two clicks for 5 seconds. Which beaker has more water in it? The size of the beaker doesn't determine the volume of water."

You say just above: "With digital, the camera has the ability to change the speed of the film now called the digital sensor." Well no it doesn't. That's a slight of hand if you will. You're correct that with film we had to deal with the film's light sensitivity. See quote from post #32 just above. Then back to the quote from post #31. You're continuing to try and define "exposure" as "proper exposure." They are two different things and it matters that they be kept separate. A digital camera can't change the light sensitivity of the sensor. It's a fixed constant. With older cameras the analog ISO gain applied to the sensor signal helped to suppress read noise and that was very real. We got better results from an old Canon 5dmkii if we raised the ISO as indicated. We're rapidly moving past that with modern sensors. Look at the two photos in the post #61 just above yours. ISO is meaningless in those two photos. If the sensor were actually more light sensitive at ISO 800 it would record further into the shadows -- a higher ISO film would do that. If like film ISO 800 really made the sensor more light sensitive it would have more DR and record both extreme highlights and shadows better than ISO 100. That's not happening in those photos.

I determined the exposure necessary to place the highlight of the lamp at saturation after ISO 800 brightening was applied. I set that exposure and took the photo both with the ISO at 800 and again at ISO 100. Both photos were taken at the same exposure (shutter speed + f/stop) and the exposure and only the exposure was responsible for what the sensor recorded. PERIOD! In both images the sensor recorded the exact same data PERIOD because both exposures were the same. ISO was meaningless. ISO 800 did not make the sensor more light sensitive. With virtually no read noise because the sensor is ISO invariant I had the same data to process in both raw files. There is noise in the shadows because of the extreme DR of the photo. The noise is 100% a function of exposure -- ISO has nothing to do with it -- noise in both photos is the same because the exposure was the same. The only thing ISO could do for me in that situation is give me a JPEG to chimp from the LCD which I need like I need a hole in the head.

Joe

 

[Designer]

I wonder if the OP is still reading this.

 

[n614cd]

@Tim Tucker 2

See what happens when I post quickly just before a meeting...
Correct, changing ISO does not affect the sensor sensitivity. Depending on camera, it affects the gain applied to the analog signal coming off the sensor and/or the digital processor.
As for the rest of your post, umm I do not follow.

Tim

 

[AlanKlein]

I never even HEARD of the so-called exposure triangle until well after the year 2000. Seriously. I learned that exposure was Intensity x Duration, with Intensity including the lens f/stop and the brightness level of the light, and duration being shutter-open time. I. Never. Ever. Heard. Of. The. Exposure. Triangle. Until.The Web.Era.

...

The reason it seemed like you never dealt with triangles before 2000, is because you shot film. With film, you were stuck with the ASA now called ISO of the film. Once in the camera, there is no way to adjust the speed ISO of a specific film except for pushing and pulling. If you always shot the same type if film, you never had to change the ASA selection in your might meter. With digital, the camera has the ability to change the speed of the film now called the digital sensor. That third selection created the triangle. Being able to change the ASA of the camera so easily, made the third selection so omnipresent. Of course, even with film, you had to enter the ASA/ISO of the film to determine the shutter speed and aperture. If you change the film speed, then you had to adjust that variable in the light meter as well just as you do in a camera. So even then you dealt with three variables.

Been here, done this. From post #32 in this thread in response to AlanKlein: "ISO is important -- never said it wasn't. Above I just confirmed it's needed to get a proper exposure. The problem shows up when you change ISO's roll and try to turn it into an exposure determinant. Read the water faucet analogy in my last post."

From post #31 in this thread in response to WayneF: "You're going to turn on the water and fill a beaker (ISO). You have constant water pressure at the time (scene luminance). The faucet handle is a little special and is equipped with click stops so that you can open it one, two, three, four, etc. clicks and each click opens the value more (aperture). You take an 8 ounce beaker and hold it under the faucet and open it two clicks for 5 seconds (time - shutter speed). The beaker nearly fills. Congratulations! Set that aside. Now reach up on the shelf and grab a 16 ounce beaker. Hold the 16 ounce beaker under the faucet and open it two clicks for 5 seconds. Which beaker has more water in it? The size of the beaker doesn't determine the volume of water."

You say just above: "With digital, the camera has the ability to change the speed of the film now called the digital sensor." Well no it doesn't. That's a slight of hand if you will. You're correct that with film we had to deal with the film's light sensitivity. See quote from post #32 just above. Then back to the quote from post #31. You're continuing to try and define "exposure" as "proper exposure." They are two different things and it matters that they be kept separate. A digital camera can't change the light sensitivity of the sensor. It's a fixed constant. With older cameras the analog ISO gain applied to the sensor signal helped to suppress read noise and that was very real. We got better results from an old Canon 5dmkii if we raised the ISO as indicated. We're rapidly moving past that with modern sensors. Look at the two photos in the post #61 just above yours. ISO is meaningless in those two photos. If the sensor were actually more light sensitive at ISO 800 it would record further into the shadows -- a higher ISO film would do that. If like film ISO 800 really made the sensor more light sensitive it would have more DR and record both extreme highlights and shadows better than ISO 100. That's not happening in those photos.

I determined the exposure necessary to place the highlight of the lamp at saturation after ISO 800 brightening was applied. I set that exposure and took the photo both with the ISO at 800 and again at ISO 100. Both photos were taken at the same exposure (shutter speed + f/stop) and the exposure and only the exposure was responsible for what the sensor recorded. PERIOD! In both images the sensor recorded the exact same data PERIOD because both exposures were the same. ISO was meaningless. ISO 800 did not make the sensor more light sensitive. With virtually no read noise because the sensor is ISO invariant I had the same data to process in both raw files. There is noise in the shadows because of the extreme DR of the photo. The noise is 100% a function of exposure -- ISO has nothing to do with it -- noise in both photos is the same because the exposure was the same. The only thing ISO could do for me in that situation is give me a JPEG to chimp from the LCD which I need like I need a hole in the head.

Joe

Legal and technical arguments that are meaningless in the real world.

 

[n614cd]

Since you are locked into the "exposure triangle", let me add another variable; the light. So now you have an "exposure square" to learn and pass on to the newbs. Try not to confuse them.

Nope. I actually never read about it until a couple of recent threads since I am recent member here. Back in roughly 2004, when I decided I to get into digital photography as a hobby I bought a couple book on how digital cameras work, and a second book on image composition. From these I created my own notes, then experimented to learn on my own. Thinking back, one of most hilarious lessons was I got aperture and DoF relationships backwards; so I happily went around taking pictures with my a new DSLR for a year and copied them onto a computer but never actually looked at them on anything larger then the LCD screen on the back of the camera. At the same time, my wife thankfully continued with the point/shoot for images. After about a year, I decided I better start learning about processing the images, and that was when I actually realized I had it completely backwards! I ended up deleting almost every image I took with the DSLR; almost everything was out of focus since I had shot almost everything wide open. I ended up only keeping the ones my wife did with the "cheap" point/shoot!.

Tim

 

[Ysarex]

I never even HEARD of the so-called exposure triangle until well after the year 2000. Seriously. I learned that exposure was Intensity x Duration, with Intensity including the lens f/stop and the brightness level of the light, and duration being shutter-open time. I. Never. Ever. Heard. Of. The. Exposure. Triangle. Until.The Web.Era.

...

The reason it seemed like you never dealt with triangles before 2000, is because you shot film. With film, you were stuck with the ASA now called ISO of the film. Once in the camera, there is no way to adjust the speed ISO of a specific film except for pushing and pulling. If you always shot the same type if film, you never had to change the ASA selection in your might meter. With digital, the camera has the ability to change the speed of the film now called the digital sensor. That third selection created the triangle. Being able to change the ASA of the camera so easily, made the third selection so omnipresent. Of course, even with film, you had to enter the ASA/ISO of the film to determine the shutter speed and aperture. If you change the film speed, then you had to adjust that variable in the light meter as well just as you do in a camera. So even then you dealt with three variables.

Been here, done this. From post #32 in this thread in response to AlanKlein: "ISO is important -- never said it wasn't. Above I just confirmed it's needed to get a proper exposure. The problem shows up when you change ISO's roll and try to turn it into an exposure determinant. Read the water faucet analogy in my last post."

From post #31 in this thread in response to WayneF: "You're going to turn on the water and fill a beaker (ISO). You have constant water pressure at the time (scene luminance). The faucet handle is a little special and is equipped with click stops so that you can open it one, two, three, four, etc. clicks and each click opens the value more (aperture). You take an 8 ounce beaker and hold it under the faucet and open it two clicks for 5 seconds (time - shutter speed). The beaker nearly fills. Congratulations! Set that aside. Now reach up on the shelf and grab a 16 ounce beaker. Hold the 16 ounce beaker under the faucet and open it two clicks for 5 seconds. Which beaker has more water in it? The size of the beaker doesn't determine the volume of water."

You say just above: "With digital, the camera has the ability to change the speed of the film now called the digital sensor." Well no it doesn't. That's a slight of hand if you will. You're correct that with film we had to deal with the film's light sensitivity. See quote from post #32 just above. Then back to the quote from post #31. You're continuing to try and define "exposure" as "proper exposure." They are two different things and it matters that they be kept separate. A digital camera can't change the light sensitivity of the sensor. It's a fixed constant. With older cameras the analog ISO gain applied to the sensor signal helped to suppress read noise and that was very real. We got better results from an old Canon 5dmkii if we raised the ISO as indicated. We're rapidly moving past that with modern sensors. Look at the two photos in the post #61 just above yours. ISO is meaningless in those two photos. If the sensor were actually more light sensitive at ISO 800 it would record further into the shadows -- a higher ISO film would do that. If like film ISO 800 really made the sensor more light sensitive it would have more DR and record both extreme highlights and shadows better than ISO 100. That's not happening in those photos.

I determined the exposure necessary to place the highlight of the lamp at saturation after ISO 800 brightening was applied. I set that exposure and took the photo both with the ISO at 800 and again at ISO 100. Both photos were taken at the same exposure (shutter speed + f/stop) and the exposure and only the exposure was responsible for what the sensor recorded. PERIOD! In both images the sensor recorded the exact same data PERIOD because both exposures were the same. ISO was meaningless. ISO 800 did not make the sensor more light sensitive. With virtually no read noise because the sensor is ISO invariant I had the same data to process in both raw files. There is noise in the shadows because of the extreme DR of the photo. The noise is 100% a function of exposure -- ISO has nothing to do with it -- noise in both photos is the same because the exposure was the same. The only thing ISO could do for me in that situation is give me a JPEG to chimp from the LCD which I need like I need a hole in the head.

Joe

Legal and technical arguments that are meaningless in the real world.

Oh by all means lets visit the real world. I was asked (friends) to take some photos at an event (no flash please just blend in quietly). Here's one of those real world photos:

That's the JPEG my camera created. I left the ISO at base (200) and to get a fast enough shutter speed for hand-holding I used the EC adjustment on the camera (Fuji XE-2) and set it to -1.67 (EXIF data is in the photo if you want to check). Now be honest; would you have raised the ISO until you had a better "proper exposure" of the gentlemen at the table?

Joe

 

[n614cd]

@Ysarex,

Photo A is the 125 ISO.
Photo B is the 1000 ISO.

Two points, photo A is slightly larger. A lower ISO in most camera's generates more data, so even when reducing with a JPEG you likely end up with a larger file.
Second, when you zoom into the glass jar and look at metal hinge, image A has a slightly more pixelated image.

As for the before after, my assumption was you would take two pictures with the same aperture and shutter speed just changing the ISO. Then "brighten" the lower ISO via post processing to be the same rendered level; and include the histograms. I know with older cameras (such as I have with a Canon 6D), the ISO affects the raw data output. As you pointed out, more and more cameras seem to be headed in the direction of invariant ISO in terms of raw data.

Tim

 

[Ysarex]

@Ysarex,

Photo A is the 125 ISO.
Photo B is the 1000 ISO.

Two points, photo A is slightly larger. A lower ISO in most camera's generates more data, so even when reducing with a JPEG you likely end up with a larger file.
Second, when you zoom into the glass jar and look at metal hinge, image A has a slightly more pixelated image.

As for the before after, my assumption was you would take two pictures with the same aperture and shutter speed just changing the ISO. Then "brighten" the lower ISO via post processing to be the same rendered level; and include the histograms. I know with older cameras (such as I have with a Canon 6D), the ISO affects the raw data output. As you pointed out, more and more cameras seem to be headed in the direction of invariant ISO in terms of raw data.

Tim

You got them reversed. Photo A is ISO 1000 and Photo B is ISO 125. And I'll take that as proof that your original assertion is incorrect. It may have been -- it isn't now. Make sure and have a look at the two photos I posted for you from my XT-2 which is more ISO invariant than the G7. They're a much closer match. In this set you can't argue that use of ISO 1000 was needed or that it provided any value. You can't tell them apart.

I would never try this with a Canon 6D, I used to shoot 5Ds before I upgraded to Fuji. Those Canons were anything but ISO invariant. It remains true that ISO affects the raw data -- absolutely. Increasing ISO reduces DR and that can be very meaningful. Interestingly although it's usually not an issue, when it is, it's typically not desirable.

Joe

EXIF data intact:

 

[n614cd]

I posted two photos for you earlier that met your criterion and used my Canon G7 which is surprisingly ISO invariant for a little compact. I think they're adequate and refute your assertion but just in case you want to get super fussy as there are some subtle differences I went ahead and hauled my XT-2 out of the closet. The XT-2 is considerably more ISO invariant than the G7 -- in fact for all practical purposes it is fully ISO invariant. Just so you have no wiggle room whatsoever, here's proof you were talkin' nonsense. EXIF data is in place so you can check them. I'm going to post them with links so you can have them at full res and can pixel peep your eyes out if you like. NOTE: I also went ahead and shot a very high contrast scene this time so it pushes limits.

....
I don't believe there's any reason to note which one is which.

First photo ISO 100, exposure at f/10 1/2 sec.: ISO_100_xt2.jpg
Second photo ISO 800, exposure at f/10 1/2 sec.: ISO_800_xt2.jpg

Joe

Sorry for the slow reply, after posting yesterday and going into a meeting I have been way to busy to respond. Did I get it right?

That is really neat. A five minute look, I could not tell. Very cool! Nice to see what is going on with newer cameras.
I think the only point we disagree on, is I am not going to fight the tide about what most people call "exposure"
I know what it is technically, and I know what a lot of photographers mean by it.


Tim

 

[n614cd]

@Ysarex

ack, I was looking at upgrading my gear the past few weeks (which is how I found this forum) and I decided against it for now. The reality, for the pictures I take now (landscape, vacations stuff, family, friends....) my Sigma lenses and Canon 6D are "good enough" (ok, my older kit lenses suck), and I was planning to wait till some point next year when the mirrorless market might start to shake out a bit.

Then I read about the invariant ISO sensors, and look at the image from the Fuji....


Tim

 

[Ysarex]

I posted two photos for you earlier that met your criterion and used my Canon G7 which is surprisingly ISO invariant for a little compact. I think they're adequate and refute your assertion but just in case you want to get super fussy as there are some subtle differences I went ahead and hauled my XT-2 out of the closet. The XT-2 is considerably more ISO invariant than the G7 -- in fact for all practical purposes it is fully ISO invariant. Just so you have no wiggle room whatsoever, here's proof you were talkin' nonsense. EXIF data is in place so you can check them. I'm going to post them with links so you can have them at full res and can pixel peep your eyes out if you like. NOTE: I also went ahead and shot a very high contrast scene this time so it pushes limits.

....
I don't believe there's any reason to note which one is which.

First photo ISO 100, exposure at f/10 1/2 sec.: ISO_100_xt2.jpg
Second photo ISO 800, exposure at f/10 1/2 sec.: ISO_800_xt2.jpg

Joe

Sorry for the slow reply, after posting yesterday and going into a meeting I have been way to busy to respond. Did I get it right?

That is really neat. A five minute look, I could not tell. Very cool! Nice to see what is going on with newer cameras.
I think the only point we disagree on, is I am not going to fight the tide about what most people call "exposure"
I know what it is technically, and I know what a lot of photographers mean by it.


Tim

I have no delusions that I'm going to banish stupid from Youtube or escort the ET out behind the barn from whence it will not return. I know what most photographers think they mean when they say "exposure." I however have the official responsibility to be guardian of the truth. I get a paycheck for it. And contrary to what Alan claims understanding the distinction here and knowing how these things actually work does translate into the real world of taking photos.

Joe

 

[AlanKlein]

Oh by all means lets visit the real world. I was asked (friends) to take some photos at an event (no flash please just blend in quietly). Here's one of those real world photos:

View attachment 165179

That's the JPEG my camera created. I left the ISO at base (200) and to get a fast enough shutter speed for hand-holding I used the EC adjustment on the camera (Fuji XE-2) and set it to -1.67 (EXIF data is in the photo if you want to check). Now be honest; would you have raised the ISO until you had a better "proper exposure" of the gentlemen at the table?

Joe

Without knowing the aperture and shutter settings, I would have no way of answering your question intelligently.

 

[n614cd]

I have no delusions that I'm going to banish stupid from Youtube or escort the ET out behind the barn from whence it will not return. I know what most photographers think they mean when they say "exposure." I however have the official responsibility to be guardian of the truth. I get a paycheck for it. And contrary to what Alan claims understanding the distinction here and knowing how these things actually work does translate into the real world of taking photos.

Joe

Here you go: xkcd: Duty Calls
I also tilt at windmills occasionally. Not as often as when i was younger, I am getting even more cynical as I age (and most think I am cynical enough).
Good luck, I have gone back and read Alan's post a few times and I still cannot follow what he is postulating. Or at least I cannot reconcile it with what I know.

Tim