Units of measure for sliders

Is there a posting or document that describes the units of measure that are used in the various sliders and what they mean. For example, with the exposure slider, what numbers are the equivalent to +/- one stop or fractions of a stop. What does each increment in sharpness or for highlights or shadows, etc., represent? Are they all linear adjustments or on a curve? Exponential? Percentages? I’ve figured out through trial and error the effects to expect usually, but it would be helpful to have an explanation of what those numbers represent so that I can better understand the effects and interactions and avoid unexpected consequences and more quickly make the adjustments to achieve the results I’m seeking.

1 Like

Screen Shot 12-14-22 at 11.33 AM
these settings are (roughly) - 1/3 EV

But does it help you with your edits – I’m not very sure about it.
It’s way more important to use a good screen (and even better when calibrated).

The monitor is your interface to the digital world, but it depends on what YOU need. :man_shrugging:

1 Like

An easy answer is to not rely on numbers but on what you see on screen, provided your screen is calibrated.

Fully agree on that. Keep also in mind @cmcgill that photography is not an exact science with measurements exact to 3 digits behind the decimal. Lots of photographic parameters like aperture, ISO, focal length, shutter speed are expressed in easy-to-remember numbers. But measuring them is a nightmare for people in need of exact numbers. 1/1000 sec can be 1/968 or 1/1132, depending on circumstances like mechanical wear or temperature. So, if PL’s adjustment would give you exactly -⅔ EVF, what could you do with that information?


I took the risk of this exercise.
It should be updated, but I am exhausted by all the work that remains to be done.



Thank you. Even though I’ve used PL Elite now for a number of years. I learned some things, e.g.: always prefer high quality previews checkbox; and the brief discussion on scale of values and amplitude of correction, which gives me a better idea of the scale of corrections to expect, without having to resort completely to trial and error…


1 Like


Thank you for the reply. It helps when first considering overall adjustments I might want to make to best represent the scene as I saw it. For example, if I adjust the exposure compensation to achieve the best exposure for the overall image, how much might I want to think about adjusting the selective tone controls or the tone curve for those areas over/under exposed. How do they interrelate from the standpoint of settings. An example of how understanding the scaling helps is having the scaling in the white balance temperature settings. Because it is based on a recognized Kelvin scale, it helps me get closer to the white balance as I saw it quicker while editing, while at the same time clueing me into some adjustments I may want to make to the camera settings in the future (I recently added a new camera to my arsenal that I’m still learning).

I agree it’s important to use a good screen, I edit on a reasonably good calibrated external Apple/LG 27in 5K monitor.



I don’t need exact precision. Just looking to better understand the numerical scales behind some of the sliders or other numerical settings. When I look at the exposure compensation slider, it’s not expressed in terms of -2/3 stop. At least with my cameras, -0.66 does not correlate to -2/3 stop; it is usually close to a n approximation of a full step when compared to images taken in -1/0/+1 stop bracketing sequence. I might use that information to modify camera settings if I was consistenly adjusting images from a camera by -2/3 EV.



Agree that in the end, it’s not the numbers, but what you see on the screen (I have a good, calibrated monitor). But computers are all about numbers, and I’ve been around computers a long, long time. Understanding what’s behind the numbers helps me focus in on the settings numbers that I need to portray the image as I saw it more quickly and accurately.


Well @cmcgill you confuse phototechnical numbers and units. There are worldwide standards about the length of 1 meter, the weight of 1 kilogram including the reference conditions. In phototechnic and even more so app-programming, none of this counts anymore. Some number system give a double value, when doubled, others give a small percentage increase, there’s hardly a common, legal standard. Instead of shooting 0.0005 sec, we’re using the term 1/2000, same with ISO (which in it’s today has nothing to do with International Standard Organization, it’s just a borrowed abbreviation - no one uses the proper description ISO 21°/100, which stands for two different ways to estimate film sensitivity and unfortunately the clunky “double sensitivity, double number” old ASA system won. What needs more space on a display “102.400 ISO” or “51 DIN”?). Also, setting the AF micro adjustment to +6 doesn’t mean, focus is 6 mm in front of the target. Or that every camera with this number in the micro adjustment is the same distance “off”. Each manufacturer bakes his own special cake and it always has to be broken into fractions, so the photographic teachers have to waste a bit more time to explain what f/8 means.

And the few people in the world used to their imperial system don’t get confused by decimals… I think it’s pointless to know more unsystematic relations between “here we do it that way, but here it’s the opposite and we need to fractionate result and square root it afterwards” - no image ever became better by staying true to numbers. We need them to define something, to compare and to tell the apps how bright or red a pixel has to be.

Photography is no science. Photogrammetry is, but for that the need of calibrated technic stuff goes far beyond what we spend.

And at the end of the day it’s you deciding how bright and red the pixel has to be to look good.

A couple of cameras also allow me to adjust the exposure generally (no compensation, just one firmware setting to use compensation less often). I hesitate to fool around with that - but I would, if I had to deliver always the same sort of image of a subject with always the same sort of background and lighting. It boils down to “in this app I need to be careful with that slider, while the other needs to be pushed to the limit to show an effect - and in another app it’s even more complicated…” Each tool has strong and weak spots and each good craftsman learns to recognize and use them.

Thank you for taking the time and trouble to respond. In the end, I’m just trying to figure out how to get the brightness and redness of the pixelI want in a more efficient (for me) manner without creating unwanted consequences for the other pixels.

I expect there to be some amount of trial and error to get the image I’m seeking, but I find I’m spending too much time with the trial and error. Having unit-less sliders with numbers would be to me rather like having apertures on a lens marked 1, 2, 3, etc., instead of the focal ratio, and the exposure settings also marked 1, 2, 3 instead of approximate shutter time, even if the markings are not precise. When I go from camera to camera, I have an idea what result I might get for depth of field at f/5.6 on my full-frame lenses and that I have to adjust to F/2.8 to get roughly the same DOF on my micro 4/3 lenses. I know that if I adjust the f ratio by one stop, I’ll need to double or half the exposure setting to achieve roughly the same level of brightness. I’m looking to better understand the slider adjustments and the correlation with other sliders in a similar manner.

You’re going to drive yourself to drink with all this emphasis on numbers. The values you see are nothing more than relative indicators of the amount of correction applied to the image. They do not represent any standards of exposure or ISO numerical settings/values you might see on your camera. Do yourself a favor and don’t be so anal. Adjust the slider, look at your image. Simple. If you like what you see and have numerous other images to adjust similarly, make a preset and be DONE with it!

1 Like