Monitor brightness - 1/15th @ f8 100 iso

I think I found that advice, using a quick web search. It appears in the web site Eric wrote in 2009 while he was at MIT, before he was hired by Adobe. The web site is an expert guide about using the Epson 3800 printer, which is why I started following Eric…I owned the same printer at the time (and still run a 3880) and his website is still a valuable resource about the 38xx series and its printer driver software, especially its Advanced Black and White mode.

On this page…

https://people.csail.mit.edu/ericchan/dp/Epson3800/printworkflow.html

…Eric wrote:

However, in case you don't have such a colorimeter package, you can still get a reasonable estimate for an appropriate brightness of the display, if you have a digital camera with a spot meter. Here's the procedure: Open a blank white window, e.g., in a web browser, in Photoshop, in MS Word, etc. Give yourself lots of blank white space. Point your camera's spot meter at the white space. Set the camera to manual exposure, f/8, 1/15 sec, ISO 100. Adjust the brightness of the display till the exposure indicator lies at the middle of the camera's exposure scale. If you can accomplish this, then the display will be at roughly 100 cd/m2.

So, what that means is that technique could work, if 100 cd/m² is your target luminance. But even for print alone, the best print-matching luminance can vary, for example influenced by the light level in the intended print display location, or what light level is set in a client’s viewing booth for contract proofs.

Knowing your target luminance is an important question today, because the range of target luminances has been expanding. 90–120 cd/m² is a typical range for print, but is far below the maximum luminance of today’s displays (most now reach 300 to 500). For someone mostly editing images for publishing on websites and mobile device apps (and which might never be printed), a higher luminance can make more sense, such as 130-160 cd/m², because many users set their phones and computers to higher brightness levels than print professionals. And if you are using the new HDR editing in Lightroom Classic as part of an end-to-end HDR workflow, then the display should be able to reach 1000+ cd/m².

So figure out your real needs first, and determine the target luminance for that. If you find that your target is not 100 cd/m², then Eric’s tip won’t result in the luminance level you want.

I know that these days most hardware calibrators show the brightness level of the monitor but unfortunately mine (Spyder 4 Express) does not.

By @paul-w

The more affordable profiling devices might not display the current luminance, but practically all of them should let you set your target luminance when you create a profile, so that’s how I would work around it. I would simply have it make a new profile at my target luminance (for example 110 cd/m²), color space, white point, and gamma, and when it’s done and applies the profile, I know it’s 110, because that is what I told it to do. For some profiling software, if you don’t see a luminance setting, it might be using an “easy” preset; look for an Advanced mode that lets you enter values.

I have no idea what the rest of the context for that is (there has to be more) - but you don't need it. There is a much simpler reference for monitor brightness: white paper.

Monitor white should be a visual match to paper white.

Of course there are many variables in this, such as ambient light, print viewing light, and, often underrated, application interface. But the emphasis here is on visual match. That takes most of these variables into account. It's not about numbers, it's all about seeing paper white on screen. Use your eyes and trust them.

You can set this using the monitor's OSD controls. You don't need to set a number in the calibrator software, except that it's nice to have a good number to go back to if you found something that works.

You can do the same for monitor black, matching it to max ink density. Most monitor have way too deep blacks compared to even the best print. That way you can get surprisingly close to the holy grail: what you see is what you get. You often hear that "screen and print can never match". That's not true; they can - if the endpoints match, the rest will fall into place.

Obviously, all this is shot to pieces if you go into HDR territory. But HDR isn't a common reference anyway, you cannot share an HDR image because it will in any case look terrible on any of the standard monitors that 99.9 % still have.

But white paper is a reference we all share, and for any workflow that may at some point include printing, it's a valid and absolute reference.

Setting the monitor white point is not part of the color management chain. In the monitor profile, white just remaps to white, whatever that white looks like. Same goes for the black point. Setting these endpoints defines the framework that color management works within.