monitor calibration

[xpatUSA]

The ISO standards have their own language and that is definitely not what most of us who have a formal background in photography generally studied in the digital age.

Wow!

[Polar01]

It seems to me that this post has walked away from the original question, prints are darker than they appear on monitor, not the meaning of exposure.

Cheers: Al

[xpatUSA]

It seems to me that this post has walked away from the original question, prints are darker than they appear on monitor, not the meaning of exposure.

Cheers: Al

While "prints darker than they appear on a monitor" is easily addressed, Al, the meaning of exposure appears to be moot, thereby attracting controversy.

Personally, I've said my piece and am done with it.

[DanK]

It's obvious that nothing one does in post can change the exposure of the capture. The more interesting question is what the "exposure" adjustment actually does. This question isn't as obvious as it seems, either for the exposure slider (here I'm talking about ACR and LR), the "temperature" adjustment (which obviously also doesn't change the color temperature of the light at the time of capture), and several other adjustments.

The color temperature adjustments are 'what if' adjustments. If you move the slider to a higher Kelvin, the image turns more yellow, not more blue, the opposite of what happens when you change the color temperature of the light at capture. I think this is telling you: "how should this capture be rendered if it had been captured under lighting of X Kelvin?"

I had thought that the "exposure" slider was analagous: how would this image be rendered if it had been exposed differently? It appears not to be. It appears to be primarily an adjustment of the brightness of the midtones.

While it doesn't trouble me at all when words are used to describe processing as well as capture, I think this is misleading. It would have been better to label it "midtones". That would match the labeling of the other sliders, e.g., highlights and shadows.

[xpatUSA]

It's obvious that nothing one does in post can change the exposure of the capture. The more interesting question is what the "exposure" adjustment actually does. ...

... I had thought that the "exposure" slider was [analogous]: how would this image be rendered if it had been exposed differently? It appears not to be. It appears to be primarily an adjustment of the brightness of the midtones....

The GIMP has an "exposure" adjustment dialog. It claims to adjust an image by scaling it in stops.

I measured a Kodak step-wedge image as-is and at plus 0.5 stops and also at minus 0.5 stops. Plotting the grayscale profile of each image in ImageJ shows that the "exposure" adjustment only changes the slope of the profile with no favor given to any particular range of tones. So, at least the GIMP makes sense in that regard ...

[DanK]

I read somewhere that the first iteration of the LR/ACR "exposure" control did much the same, but I have no way of knowing whether that's correct.

I general, I don't much like the LR/ACR sliders, which apply a predetermined algorithm to tonality adjustments rather than giving the editor control. I had a bit of an argument about this with someone who co-taught an introductory Photoshop class with me last year. She liberally used the "contrast" slider. I rarely use it, and almost only for casual work. I explained to the students that a simple curve allows you to control where the histogram is expanded and compressed, while the contrast slider give you no control over anything but the total amount of the adjustment. However, this is off topic for this thread.

[Manfred M]

Wow!

Not Wow!

It is not something that someone needs to understand to be a successful photographer and irrelevant to most. The schools are turning out photographers whose income is going to be dependent on their ability to compose, take and most importantly sell their work. The intricacies of ISO standards don't matter.

I'm fairly certain most people driving a car know nothing about the Carnot cycle, which explains the thermodynamics of how an internal combustion engine works. I suspect most drivers have no idea of how a powertrain works (or the main components that go into it and what they do), yet have no issues at all driving their car.

[Cantab]

Dan and Ted, thank you for this information -- previously unknown to me -- about the effect of the exposure slider in Lightroom. I had always assumed it operated in the fashion that Ted describes in GIMP.

Next time I use the exposure slider I'll try to remember to pay close attention to what is actually happening. And then I'll see if this additional knowledge actually changes how I use the exposure slider or whether I'll just continue following a long establish habit!

[DanK]

Bruce,

If you put the cursor over any of the Lightroom tonality controls, a faint light gray appears on the histogram covering the most affected tonal ranges. I don't see this feature in the Adobe Camera Raw filter.

Dan

[Cantab]

Bruce,

If you put the cursor over any of the Lightroom tonality controls, a faint light gray appears on the histogram covering the most affected tonal ranges. I don't see this feature in the Adobe Camera Raw filter.

Dan

I'll have a look later today. Thank you.