shooting max ettr shifts the WB. i prefer just to shoot correct and lift shadows.theres very little dofference in shadow noise.
shooting max ettr shifts the WB. i prefer just to shoot correct and lift shadows.theres very little dofference in shadow noise.
@xpatUSA has written: @bobn2 has written: @xpatUSA has written:sensor exposure i.e. ISO's meaning thereof
ISO doesn't have a meaning of 'sensor exposure'.
My copy has written:3.2
exposure index
EI
numerical value that is inversely proportional to the exposure provided to an image sensor to obtain an imageAs you should know, "EI" is their term for what most people call "the ISO"
Not quite right. 'EI' is what they call any exposure index. It's defined in the standard:exposure index
EI
numerical value that is inversely proportional to the exposure provided to an image sensor to obtain an image
Note 1 to entry: Images obtained from a DSC using a range of exposure index values will normally provide a range of image quality levels.
People who think it's 'the ISO' are under the misapprehension that all the defined exposure indices would give the same result. As they say explicitly above, they won't. The ISO EI used can be found in the EXIF.
My main point edited out of the quote and my side-ref seized upon as a Straw Man, so ...
... 'bye
@DonaldB has written: @DannoLeftForums has written:per unit area
explain please.
I assume this was the definition of 'exposure'. Consider the definition of exposure that most will be taught at photography school, H=E*t. Here 'H' is exposure, 'E' is image plane illuminance, often called more simply 'intensity', and 't' is exposure time. E*t is usually explained as an 'amount of light', but lets think a bit more carefully. 'Intensity' doesn't refer to an amount of light, it refers to how intense is the flow of light, that is the amount of light per unit area, so in fact exposure is amount of light per unit area.
We can also come to the same conclusion using a units analysis. The SI unit of luminance or intensity is the lux, so the unit of exposure is lux seconds, directly from the equation above. If you look up your SI units, you find that the lux is a name for lumens per square metre. so in other terms the unit of exposure is lumen seconds per square metre.
You can carry on this type of units analysis. You find that the lumen is the unit of luminous power (which is why light bulbs are now rated in lumens). High school physics tells you that power * time = energy, so exposure is luminous energy per square metre (or any other unit area, if you adjust all the units appropriately).
Cheers thanks Bob. i had read about per square meter for lumens, but couldnt get my head around per unit area. eg: sensor area 36x24mm 0.00091m2
@DonaldB has written: @SrMi has written:We do not need raw histograms when shooting at higher ISOs. Is that correct?
i will make that test for you you and post the reasults to see if it matches the general concensus.
Before you do it, please describe what are you going to do.
Im going to shoot my doll in the studio with a black background. im going to fix exposure and raise iso and adjust ambient light (colour corrected LED)and compare what the live histograms and taken image histograms look like. i will also fix the iso and lighting and float the exposure to see if there is any difference in WB as well as the raw histograms in FRV.
@xpatUSA has written:Has ISO 12232 changed in that regard? My 2006 copy doesn't specify an amount of headroom per se, but following their math for both the saturation-based and the standard output sensitivity methods gives 1/2-stop and none, respectively.
They define different exposure indices which may or may not provide different results. The saturation based ISO speed provides a definition based on the maximum signal level. The Standard Output Sensitivity exposure index provides for an exposure producing 18% in the output file. You can put the two together and come to the conclusion that they were supposed to produce the same numerical value with a given headroom (as I used to do) but the 2019 edition tells us that was wrong. They say 'Note 1 to entry: The ISO speed is usually the highest exposure index value that still provides peak image quality for normal scenes. However, a DSC does not necessarily use the ISO speed value as the exposure index value when capturing images.' For SOS they say 'Note 1 to entry: SOS provides a practical exposure index value based on the signal level of images captured with a DSC, but images taken using this exposure index value do not necessarily provide the best image quality.'
The truth is that ISO 12232 is a mess top to bottom, and 2019 is chock full of political compromises.
forget about iso being acurate across cameras, whats worst is F vers T stops ๐คจ
@IliahBorg has written: @DonaldB has written: @SrMi has written:We do not need raw histograms when shooting at higher ISOs. Is that correct?
i will make that test for you you and post the reasults to see if it matches the general concensus.
Before you do it, please describe what are you going to do.
Im going to shoot my doll in the studio with a black background. im going to fix exposure and raise iso and adjust ambient light (colour corrected LED)and compare what the live histograms and taken image histograms look like. i will also fix the iso and lighting and float the exposure to see if there is any difference in WB as well as the raw histograms in FRV.
Suppose you fixed the exposure (light, aperture, shutter speed) in such a way that the histogram touches the right edge at ISO 12800. How much quality is lost if you shoot at the same exposure with the camera set to ISO 1600?
When exposure is already maximized, and you are above ISO 1600, how much does it matter if the histogram doesn't touch the right edge?
@DonaldB has written: @IliahBorg has written: @DonaldB has written: @SrMi has written:We do not need raw histograms when shooting at higher ISOs. Is that correct?
i will make that test for you you and post the reasults to see if it matches the general concensus.
Before you do it, please describe what are you going to do.
Im going to shoot my doll in the studio with a black background. im going to fix exposure and raise iso and adjust ambient light (colour corrected LED)and compare what the live histograms and taken image histograms look like. i will also fix the iso and lighting and float the exposure to see if there is any difference in WB as well as the raw histograms in FRV.
Suppose you fixed the exposure (light, aperture, shutter speed) in such a way that the histogram touches the right edge at ISO 12800. How much quality is lost if you shoot at the same exposure with the camera set to ISO 1600?
When exposure is already maximized, and you are above ISO 1600, how much does it matter if the histogram doesn't touch the right edge?
will do that test .
Cheers thanks Bob. i had read about per square meter for lumens, but couldnt get my head around per unit area. eg: sensor area 36x24mm 0.00091m2
Area doesn't have to be specified in MKS units. You could specify it in square mm, square um, or even square nm, as well as acres, sections, and square furlongs.
My lighting could only range from 1600 to 8000 just clipping both hisograms. in reallity its that close it doesnt really matter . the 1600 image shows a fraction less noise in the shadows but thats looking a 2000%.
@JimKasson has written: @WhyNot has written:I can understand this but not sure how that helps or improves my understanding of the resulting image over seeing what the camera believes will be my converted image
At the time of the exposure, the camera can't know how you will process the raw file.
While I can understand how this might be interesting to me as a software developer, I'm still not sure what information I'm reading from the Raw Histogram that effects what I do before I press the shutter ...
WhyNot
Some may find it useful to look at the tonal distribution presented as a histogram but really, don't most of us just want our cameras to reliably tell us when our raws, not jpegs, are blown. Why is it so hard?
My lighting could only range from 1600 to 8000 just clipping both hisograms. in reallity its that close it doesnt really matter . the 1600 image shows a fraction less noise in the shadows but thats looking a 2000%.
Fix the exposure (including lights) so that at ISO 8000 the histogram touches the right edge. Shoot at ISO 8000, ISO 1600, ISO 800 changing nothing but ISO setting.
@DonaldB has written:Cheers thanks Bob. i had read about per square meter for lumens, but couldnt get my head around per unit area. eg: sensor area 36x24mm 0.00091m2
Area doesn't have to be specified in MKS units. You could specify it in square mm, square um, or even square nm, as well as acres, sections, and square furlongs.
Quite so! Back in the day, I greatly preferred slugs which tended to get rid of the dreaded gravitational constant.
And it's good to see someone expressing his lighting in what can only be foot candles ๐
@SrMi has written: @xpatUSA has written: @SrMi has written: @xpatUSA has written: @SrMi has written: @xpatUSA has written:[quote="@SrMi"]
We do not need raw histograms when shooting at higher ISOs. Is that correct?If the statement applies to all digital cameras, it is not correct - sorry.
It does not apply to cameras where the sensor output is amplified according to the ISO setting before being input to the ADC. Therefore, it is incorrect for most digital cameras.
For the latest Sony, Canon, Nikon, and Leica cameras (all the latest digital cameras?), there is very little or no penalty when "underexposing" by keeping the ISO a few stops lower than the maximum possible while keeping the exposure unchanged.
<>Interesting how things change. In my world, lowering the ISO increases the sensor exposure, not "underexposes".
Lowering ISO does not change exposure if you keep exposure fixed, as I wrote above.
Lowering ISO can increase exposure if you let the camera change the exposure automatically.On your camera, I assume ... definitely not on mine ...
It does on a a Sony, Nikon, Leica, Canon .... What camera do you have where with constant shutter speed and constant aperture the exposure changes with ISO?
Jim, @SrMi,
I mostly shoot with a Sigma SD9 in Manual mode.
Twiddling the ISO does not change "the exposure" one little bit. The resulting raw histograms are all the same.
Changing the ISO does alter the metering "needle" and one is prompted thereby to change the exposure EV appropriately.
That is because the camera's meter is actually an image lightness and not exposure* meter. Image lightness and exposure* are two different things.
Camera meters are calibrated to output an average 18% grey image lightness for the exposure* that is set.
In manual mode with a fixed aperture and shutter speed raising iso by 1 stop after the meter needle was centred will shift the needle 1 stop to the right because you are lightening the image by 1 stop without altering the exposure*.
* exposure - amount of light that struck the sensor per unit area while the shutter was open.
well that showed my eye af works to -3.5 ev ๐ going to resend fixed focus images .
well that showed my eye af works to -3.5 ev ๐ going to resend fixed focus images .
@DonaldB has written:My lighting could only range from 1600 to 8000 just clipping both hisograms. in reallity its that close it doesnt really matter . the 1600 image shows a fraction less noise in the shadows but thats looking a 2000%.
Fix the exposure (including lights) so that at ISO 8000 the histogram touches the right edge. Shoot at ISO 8000, ISO 1600, ISO 800 changing nothing but ISO setting.
@IliahBorg has written: @DonaldB has written:My lighting could only range from 1600 to 8000 just clipping both hisograms. in reallity its that close it doesnt really matter . the 1600 image shows a fraction less noise in the shadows but thats looking a 2000%.
Fix the exposure (including lights) so that at ISO 8000 the histogram touches the right edge. Shoot at ISO 8000, ISO 1600, ISO 800 changing nothing but ISO setting.
Awesome test, they all look identical processed to the same brightness. DPR test subject hasnt a patch on my doll ๐