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FORUMS Photography Talk by Genre General Photography Talk 
Thread started 30 Oct 2013 (Wednesday) 11:21
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exposure compensation general question

 
tzalman
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Oct 30, 2013 17:01 |  #16

OhLook wrote in post #16411608 (external link)
I

I'd rather have EC change the way the sensor behaves than do what it does.

If it were possible, we would have variable sensors. But the Quantum Efficiency (the relationship between photons input and electrons output) of any given sensor is fixed, although over the years camera makers have increased the QE of their sensors. But we have the next best thing - the sensor is part of a complex module that incorporates onboard electronic amplifiers to amplify the output from the pixels. That is what happens when you increase the ISO. But there is a limit to how much gain can be achieved. After about a 16x - 32x increase the concurrent increase in noise makes it no longer practical.


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tzalman
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Oct 30, 2013 17:09 |  #17

flashpoint99 wrote in post #16411684 (external link)
It changes the way it meters the light.

No, you are overthinking this. It simply tells the metering software, "Do your regular metering and then add one stop," or two stops or subtract a stop, etc.


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flashpoint99
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Oct 30, 2013 17:21 |  #18

gonzogolf wrote in post #16411697 (external link)
No, it doesn't change the way it meters. It adjusts the settings to accommodate the flaw in the metering.

Ok semantics .........it adjust for the misread by the meter




  
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Oct 30, 2013 17:28 |  #19

EC just lets you change the exposure metering in the camera. In manual you don't even have EC since you set everything yourself. But I sometimes change to AV of TV so I can use EC. I have subscribed to Bryan Petersen's model of underexpose by 2/3 as the dark is easier to recover than overexposure that loses details.
If I am in AV/TV mode I can use EC to get my 2/3 underexposure. Then I let the Auto ISO pick a number that is not always on the 1/2/4/800 marks. This lets me get the most usable ISO even though it is underexposed. Then I just recover the 2/3 in LR or whatever your favorite image editing software is.


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OhLook
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Oct 30, 2013 19:10 |  #20

me wrote:
I'd rather have EC change the way the sensor behaves than do what it does.

gonzogolf wrote in post #16411645 (external link)
What do you mean by changing the way the sensor behaves? If the light is limited, then it can only borrow from one of three sources, shutter speed, aperture, or ISO. The sensor cant create any more light and if you fix one of the variables (using AV of TV modes)it has to come from one of the others.

The G15 on Av or Tv tends to overexpose at EC = 0, especially in late afternoon outdoors. I often need to go down as far as –1.333 or even –1.666. I thought the EC adjustment was reducing the sensor's sensitivity to light.


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gonzogolf
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Oct 30, 2013 21:04 |  #21

OhLook wrote in post #16411998 (external link)
The G15 on Av or Tv tends to overexpose at EC = 0, especially in late afternoon outdoors. I often need to go down as far as –1.333 or even –1.666. I thought the EC adjustment was reducing the sensor's sensitivity to light.

No it adjusts the exposure for the bias in the meter.




  
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gonzogolf
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Oct 30, 2013 21:08 |  #22

flashpoint99 wrote in post #16411778 (external link)
Ok semantics .........it adjust for the misread by the meter

Its more than semantics. The meter reads and measures whats in front of it. When you dial in EC you are changing the aperture or SS depending on the mode to accommodate the meters perceived failure.




  
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tzalman
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Oct 31, 2013 01:31 |  #23

I thought the EC adjustment was reducing the sensor's sensitivity to light.

Nothing can change the sensor's sensitivity. Changing ISO changes the amount the signal output from the sensor is amplified, just like turning up the volume on your radio. Turning up the volume doesn't make the radio's antenna more sensitive to radio waves; same with the sensor and light waves.


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OhLook
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Oct 31, 2013 10:15 |  #24

me wrote:
I thought the EC adjustment was reducing the sensor's sensitivity to light.

tzalman wrote in post #16412651 (external link)
Nothing can change the sensor's sensitivity. Changing ISO changes the amount the signal output from the sensor is amplified . . .

For those who missed my earlier post that said "I thought as you did until I read this thread. Then I took a pair of test shots and checked the settings," let me repeat that I no longer think the EC adjustment reduces the sensor's sensitivity.

But it isn't an absurd idea, is it, for one who doesn't know electronics? When you change white-balance settings, the ratio of yellow to blue changes, as if the sensor had turned down its reception of one color or turned up its reception of the other. When you shoot in black-and-white mode, saturation for all colors is zero. If the sensor's sensitivity never changes, I have to infer that all such adjustments cause a change in what happens to the signal from the sensor somewhere further along the path to a digital image. Is this inference correct?


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Oct 31, 2013 10:43 |  #25

OhLook wrote in post #16413317 (external link)
For those who missed my earlier post that said "I thought as you did until I read this thread. Then I took a pair of test shots and checked the settings," let me repeat that I no longer think the EC adjustment reduces the sensor's sensitivity.

But it isn't an absurd idea, is it, for one who doesn't know electronics? When you change white-balance settings, the ratio of yellow to blue changes, as if the sensor had turned down its reception of one color or turned up its reception of the other. When you shoot in black-and-white mode, saturation for all colors is zero. If the sensor's sensitivity never changes, I have to infer that all such adjustments cause a change in what happens to the signal from the sensor somewhere further along the path to a digital image. Is this inference correct?

When you change the ISO setting, you are effectively changing the sensitivity of the image sensor. So, no, it's not an absurd idea. ;) But it can only be taken so far. Once it's reached the limit, no further change can be made.


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Oct 31, 2013 10:50 |  #26

tzalman wrote in post #16412651 (external link)
Nothing can change the sensor's sensitivity. ....

PacAce wrote in post #16413401 (external link)
When you change the ISO setting, you are effectively changing the sensitivity of the image sensor. ....

This is what makes forums like this difficult for people to learn from.

EDITED LATER: I should add that both of this posts are made by people whose opinion I respect and I've read their posts with interest for years. They are far more technically adept than I am. My post was to point out the difficulty for new users (or even older ones that don't fully grasp the technical aspects of photography) to comprehend the many answers posted here - some of which seem to contradict each other.


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PacAce
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Oct 31, 2013 11:25 |  #27

WaltA wrote in post #16413418 (external link)
This is what makes forums like this difficult for people to learn from.

EDITED LATER: I should add that both of this posts are made by people whose opinion I respect and I've read their posts with interest for years. They are far more technically adept than I am. My post was to point out the difficulty for new users (or even older ones that don't fully grasp the technical aspects of photography) to comprehend the many answers posted here - some of which seem to contradict each other.

The key operative word that I used is effectively. ;) Remember, the camera hardware is made up of more than just the image sensor. There are amplifiers and stuff in there, also. So, although the image sensor itself has a fixed sensitivity, the electronics supporting it can change the effective sensitivity of the sensor, as can firmware. That's what changing the ISO does.

[EDIT] BTW, I was not in any way trying to contradict what Tzalman said. In fact, I'm in complete agreement with him. Sorry if my previous post sounded like I was contradicting him. I was just replying to OhLook's post.


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WaltA
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Oct 31, 2013 11:45 |  #28

Thanks, Leo that makes sense.


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Blaster6
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Oct 31, 2013 11:45 |  #29

tzalman wrote in post #16411762 (external link)
No, you are overthinking this. It simply tells the metering software, "Do your regular metering and then add one stop," or two stops or subtract a stop, etc.

Ding ding ding... we have a winner. Some of you really like to get in the weeds when a simple explanation does the trick.


No, I never claimed to be outstanding in the field of photography. I said I was out standing in the field taking photos.

  
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Blaster6
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Oct 31, 2013 11:52 |  #30

OhLook wrote in post #16413317 (external link)
When you change white-balance settings, the ratio of yellow to blue changes, as if the sensor had turned down its reception of one color or turned up its reception of the other. When you shoot in black-and-white mode, saturation for all colors is zero. If the sensor's sensitivity never changes, I have to infer that all such adjustments cause a change in what happens to the signal from the sensor somewhere further along the path to a digital image. Is this inference correct?

correct

OK, you change the white balance or shoot in B&W or sepia... what does the raw look like? What changes do you think are being made to the sensor? EC would change your recommended settings that determine the amount & duration of light reaching the sensor.

Edit:
Not trying to sound snippy but shoot RAW+JPG and see the difference. The sensor sees what the sensor sees. You can turn up the volume (I like that) or you can change the processing done to the output.


No, I never claimed to be outstanding in the field of photography. I said I was out standing in the field taking photos.

  
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exposure compensation general question
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