topic Re: How do f stops in a camera relate to the decimal adjustments in DPP4? in Camera Software

How do f stops in a camera relate to the decimal adjustments in DPP4?

stevet1 — Sun, 09 Aug 2026 03:06:17 GMT

How do the f stops in a camera related to the decimal adjustments in DPP4?

Shutter speed and aperture and exposure compensation are expressed as f stops in the camera (1/3 of a stop, 2/3, 1 stop. etc.

But if you go to DPP4 and make adjustments in brightness, highlights, shadows, contrast, etc., the adjustments are made in decimal points.

How do they relate, or do they?

Steve Thomas

Re: How do f stops in a camera relate to the decimal adjustments in DPP4?

jrhoffman75 — Sun, 09 Aug 2026 10:58:27 GMT

@stevet1 wrote:

How do the f stops in a camera related to the decimal adjustments in DPP4?

Shutter speed and aperture and exposure compensation are expressed as f stops in the camera (1/3 of a stop, 2/3, 1 stop. etc.

But if you go to DPP4 and make adjustments in brightness, highlights, shadows, contrast, etc., the adjustments are made in decimal points.

How do they relate, or do they?

Steve Thomas

Since editing adjustments are made by eye or watching the histogram I don't think a correlation to in-camera adjustment is important.

It is interesting that the adjustment range for RAW files in DPP4 is +/- 3 units, same a EC range in camera.

A quick test would be to record images at 0/1/2/3 EC in camera and then compare to the base image adjusted 1, 2, 3 in DPP4.

Re: How do f stops in a camera relate to the decimal adjustments in DPP4?

johnrmoyer — Sun, 09 Aug 2026 13:04:00 GMT

It appears to me that the brightness adjustment in DPP https://cam.start.canon/en/S002/manual/html/UG-04_EditImage_0040.html#EditImage_0050_1 matches the exposure compensataion adjustment in the camera. +1 is one stop brighter and -1 is one stop darker.

It appears to me that the "input white level" adjustment https://cam.start.canon/en/S002/manual/html/UG-04_EditImage_0040.html#EditImage_0050_11 can add up to 2 stops of dynamic range.

It appears to me that shadows, highlights, and contrast change the gamma curve in some unspecified way, but may also change the dynamic range. https://cam.start.canon/en/S002/manual/html/UG-04_EditImage_0040.html#EditImage_0110_1

It appears to me that the Color Adjustment Tool Pallet operates in HSL color space. https://cam.start.canon/en/S002/manual/html/UG-04_EditImage_0040.html#EditImage_0040_3

It appears to me that the Tone Curve adjustment allows manipulation of the gamma curve. https://cam.start.canon/en/S002/manual/html/UG-04_EditImage_0040.html#EditImage_0060_3

Re: How do f stops in a camera relate to the decimal adjustments in DPP4?

SignifDigits — Sun, 09 Aug 2026 14:34:11 GMT

Interesting question Steve. Thanks for asking. And thanks to both Johns for answering.

Re: How do f stops in a camera relate to the decimal adjustments in DPP4?

stevet1 — Sun, 09 Aug 2026 20:05:24 GMT

This is what I was talking about

These kinds of figures don't seen to relate to f stops in any way.

Steve Thomas

Re: How do f stops in a camera relate to the decimal adjustments in DPP4?

SignifDigits — Sun, 09 Aug 2026 20:46:21 GMT

Steve, you made me look! Brightness, of course, would be the primary bar that would apply. I notice a few things:

As jrhoffman75 noted above the max and min are +/- 3 - stops, just as the EC in viewfinders on Auto ISO, so MAYBE that's the case, but as he mentions that's not in the manual and the only way to know for sure is to test it
I noticed that clicking the slider bar changes it in 1/5 (maybe stops) increments, and, of course
You can input any decimal # that you want there between +/- 3.

For the rest I notice only that Contrast, Color Tone, and Color Saturation are all +/- 4 and Shadow and Highlight are +/- 5, and gamma are -10 to +5? (max is unlabeled). I am wholly uncertain of what those ranges represent.

DPP manual at https://cam.start.canon/en/S002/manual/html/index.html . johnrmoyer makes reasonable assertions, but, really, it is hard to say from just the documentation.

Again, good question. I'm curious if anyone really definitively know the answer to your question.

Re: How do f stops in a camera relate to the decimal adjustments in DPP4?

jrhoffman75 — Sun, 09 Aug 2026 21:08:57 GMT

@stevet1 wrote:

This is what I was talking about

These kinds of figures don't seen to relate to f stops in any way.

Steve Thomas

Those settings, other than brightness, have no direct relation to f/stops. They may be indirectly related in that more or less exposure may require more or less highlight adjustment, for example.

Re: How do f stops in a camera relate to the decimal adjustments in DPP4?

stevet1 — Sun, 09 Aug 2026 21:43:37 GMT

SignifDigits.

You wrote, "For the rest I notice only that Contrast, Color Tone, and Color Saturation are all +/- 4 and Shadow and Highlight are +/- 5, and gamma are -10 to +5? (max is unlabeled). I am wholly uncertain of what those ranges represent.

The Tone Curve adjustment ranges from - 100 to + 100. Figure that one out 😀

Steve