Can I use an light meter to get monitor brightness?

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al404
al404 Regular Member • Posts: 208
Can I use an light meter to get monitor brightness?

I don't have a calibration tool but I would like to print some photo

I did some test with my Canon Selphy and an ICC profile I found online and the result seems pretty accurato but the print shop recommend "The brightness of the monitor should lie between 90 and 120 cd/qm." and on MacBook seems not possible to get this data from system

I was wondering if it would be possible using camera meter, or external light meter to convert the data I read into 90 and 120 cd/qm

Or maybe sono iPhone app

WryCuda Forum Pro • Posts: 10,214
Re: Can I use an light meter to get monitor brightness?
2

al404 wrote:

I don't have a calibration tool but I would like to print some photo

I did some test with my Canon Selphy and an ICC profile I found online and the result seems pretty accurato but the print shop recommend "The brightness of the monitor should lie between 90 and 120 cd/qm." and on MacBook seems not possible to get this data from system

I was wondering if it would be possible using camera meter, or external light meter to convert the data I read into 90 and 120 cd/qm

Provided that the screen renders your images satisfactorily, there's no reason that screen brightness should have any effect on your prints.

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mclewis Senior Member • Posts: 1,279
Re: Can I use an light meter to get monitor brightness?
3

WryCuda wrote:

al404 wrote:

I don't have a calibration tool but I would like to print some photo

I did some test with my Canon Selphy and an ICC profile I found online and the result seems pretty accurato but the print shop recommend "The brightness of the monitor should lie between 90 and 120 cd/qm." and on MacBook seems not possible to get this data from system

I was wondering if it would be possible using camera meter, or external light meter to convert the data I read into 90 and 120 cd/qm

Provided that the screen renders your images satisfactorily, there's no reason that screen brightness should have any effect on your prints.

Screen brightness does affect how print look.  If your screen is too bright compared to the lighting in your print viewing conditions your prints will look too dark and vice versa.

The screen brightness you want depends on the light level in  your print viewing conditions.  You may not want it in the 90-120 cd/m2 range.  It could need to be different.

WryCuda Forum Pro • Posts: 10,214
Re: Can I use an light meter to get monitor brightness?

mclewis wrote:

WryCuda wrote:

al404 wrote:

I don't have a calibration tool but I would like to print some photo

I did some test with my Canon Selphy and an ICC profile I found online and the result seems pretty accurato but the print shop recommend "The brightness of the monitor should lie between 90 and 120 cd/qm." and on MacBook seems not possible to get this data from system

I was wondering if it would be possible using camera meter, or external light meter to convert the data I read into 90 and 120 cd/qm

Provided that the screen renders your images satisfactorily, there's no reason that screen brightness should have any effect on your prints.

Screen brightness does affect how print look. If your screen is too bright compared to the lighting in your print viewing conditions your prints will look too dark and vice versa.

The screen brightness you want depends on the light level in your print viewing conditions. You may not want it in the 90-120 cd/m2 range. It could need to be different.

You can always adjust the 'brightness' of images that are being prepared for printing, using the graphics program controls.

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mclewis Senior Member • Posts: 1,279
Re: Can I use an light meter to get monitor brightness?
1

WryCuda wrote:

mclewis wrote:

WryCuda wrote:

al404 wrote:

I don't have a calibration tool but I would like to print some photo

I did some test with my Canon Selphy and an ICC profile I found online and the result seems pretty accurato but the print shop recommend "The brightness of the monitor should lie between 90 and 120 cd/qm." and on MacBook seems not possible to get this data from system

I was wondering if it would be possible using camera meter, or external light meter to convert the data I read into 90 and 120 cd/qm

Provided that the screen renders your images satisfactorily, there's no reason that screen brightness should have any effect on your prints.

Screen brightness does affect how print look. If your screen is too bright compared to the lighting in your print viewing conditions your prints will look too dark and vice versa.

The screen brightness you want depends on the light level in your print viewing conditions. You may not want it in the 90-120 cd/m2 range. It could need to be different.

You can always adjust the 'brightness' of images that are being prepared for printing, using the graphics program controls.

Or you could set your monitor brightness correctly and not have to mess about doing that for prints.

Doug Haag Senior Member • Posts: 2,249
Re: Can I use an light meter to get monitor brightness?

al404 wrote:

I don't have a calibration tool but I would like to print some photo

I did some test with my Canon Selphy and an ICC profile I found online and the result seems pretty accurato but the print shop recommend "The brightness of the monitor should lie between 90 and 120 cd/qm." and on MacBook seems not possible to get this data from system

I was wondering if it would be possible using camera meter, or external light meter to convert the data I read into 90 and 120 cd/qm

Or maybe sono iPhone app

This topic is not unrelated to a question I had.

The monitor is a light source.  The light coming from the monitor is not reflected light.

Incident light meters measure the intensity of light falling on a subject or location that has been emitted by a light source (the sun, studio lights, etc.)  On the other hand, the camera meter is designed to measure reflected light (measuring how much of the light a surface receives from a light source is reflected rather than absorbed).  Even if the light source is identical, a black surface will absorb more and reflect less while a white surface will absorb less and reflect more.  So the camera measurements of such reflective surfaces would be different even if the light source remains constant.

My question is whether a camera's reflective meter could be adapted to work as an incident meter.  Perhaps it would involve some lens covering that works like the Expodisc to measure white balance.  But while Googling everything I can think of, I have found no reference to turning a camera's reflective meter into an incident meter.

Because the monitor is a light source requiring an incident meter to measure the intensity of light that is being received at your viewing position, I am guessing that your idea is problematic.

Social WewPet
Social WewPet New Member • Posts: 1
Re: Can I use an light meter to get monitor brightness?

thank you

D Cox Forum Pro • Posts: 26,928
Re: Can I use an light meter to get monitor brightness?

Doug Haag wrote:

al404 wrote:

I don't have a calibration tool but I would like to print some photo

I did some test with my Canon Selphy and an ICC profile I found online and the result seems pretty accurato but the print shop recommend "The brightness of the monitor should lie between 90 and 120 cd/qm." and on MacBook seems not possible to get this data from system

I was wondering if it would be possible using camera meter, or external light meter to convert the data I read into 90 and 120 cd/qm

Or maybe sono iPhone app

This topic is not unrelated to a question I had.

The monitor is a light source. The light coming from the monitor is not reflected light.

Incident light meters measure the intensity of light falling on a subject or location that has been emitted by a light source (the sun, studio lights, etc.) On the other hand, the camera meter is designed to measure reflected light (measuring how much of the light a surface receives from a light source is reflected rather than absorbed). Even if the light source is identical, a black surface will absorb more and reflect less while a white surface will absorb less and reflect more. So the camera measurements of such reflective surfaces would be different even if the light source remains constant.

My question is whether a camera's reflective meter could be adapted to work as an incident meter. Perhaps it would involve some lens covering that works like the Expodisc to measure white balance. But while Googling everything I can think of, I have found no reference to turning a camera's reflective meter into an incident meter.

Because the monitor is a light source requiring an incident meter to measure the intensity of light that is being received at your viewing position, I am guessing that your idea is problematic.

https://jimdoty.com/learn/exp101/exp_expodisc/exp_expodisc.html

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MrBrightSide
MrBrightSide Contributing Member • Posts: 868
Re: Can I use an light meter to get monitor brightness?

The answer is "maybe" and depends on the amount of time and patience you want to devote.

The more important question is what is the problem? Are your prints coming out too light? Or too dark? And what program are you using to adjust the  pictures before printing?

Have you learned about histograms?

And finally, does the photo lab you use have an "auto correct" function that is added to the photos before printing? Normally that works pretty well.

al404
OP al404 Regular Member • Posts: 208
Re: Can I use an light meter to get monitor brightness?

I also have an external light meter but the question is:

How do I know what correspond at 120 cd/mq?

al404
OP al404 Regular Member • Posts: 208
Re: Can I use an light meter to get monitor brightness?

MrBrightSide wrote:

The answer is "maybe" and depends on the amount of time and patience you want to devote.

The more important question is what is the problem? Are your prints coming out too light? Or too dark? And what program are you using to adjust the pictures before printing?

I don't know is the first time I'm sending to print as fine art, and the indication photo lab gives is 120 cd/mq photo should be correct

Have you learned about histograms?

why histogram, I cannot know if they will turn out darker or lighter there are too many thing in between

And finally, does the photo lab you use have an "auto correct" function that is added to the photos before printing? Normally that works pretty well.

Yes but I don't want the to mess everything up with auto correct after spending a loto of time editing my photo as I want

MrBrightSide
MrBrightSide Contributing Member • Posts: 868
Using your camera meter for incident light

You are correct. Incident meter readings are the gold standard for setting exposure, everything else is kludgey and imprecise.

Can you put a translucent dome over the lens and point it at your light source to get a reading? I think that may have been an actual product at some point in the past. Or  perhaps ExpoDisc can tell you how to use their product for measuring incident light.

Which brings us to the very misunderstood Kodak 18 Percent Gray Card. You can get a reading that's pretty close to an actual incident meter if you use a the gray card according to the instructions for angling the card toward the light source and then adding additional exposure compensation (it's between 1/2 stop under and 1 1/2 over depending on the subject).

It's a system that film people used for decades. I've used it in the field a few times and it's a perfectly reasonable way to measure the amount of light falling on the subject. I also measured it against my handheld light meter and it was within a third of a stop.

You can download the instructions at https://www.zonephoto.it/images/pdf/kodak-grey-card1903061.pdf

One danger: there are people who will warn you not to use an 18 percent gray card and recite meandering stories about a conspiracy between Ansel Adams and Kodak. They'll also claim they have special insider information that cameras really measure middle gray at 12 percent .

These people don't understand how the gray card technique works; they're usually also the same people who try to tell you that ISO doesn't matter.

Doug Haag wrote:

This topic is not unrelated to a question I had.

The monitor is a light source. The light coming from the monitor is not reflected light.

Incident light meters measure the intensity of light falling on a subject or location that has been emitted by a light source (the sun, studio lights, etc.) On the other hand, the camera meter is designed to measure reflected light (measuring how much of the light a surface receives from a light source is reflected rather than absorbed). Even if the light source is identical, a black surface will absorb more and reflect less while a white surface will absorb less and reflect more. So the camera measurements of such reflective surfaces would be different even if the light source remains constant.

My question is whether a camera's reflective meter could be adapted to work as an incident meter. Perhaps it would involve some lens covering that works like the Expodisc to measure white balance. But while Googling everything I can think of, I have found no reference to turning a camera's reflective meter into an incident meter.

Because the monitor is a light source requiring an incident meter to measure the intensity of light that is being received at your viewing position, I am guessing that your idea is problematic.

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TomS53 Senior Member • Posts: 1,290
Re: Can I use an light meter to get monitor brightness?

Set the monitor brightness to about 50% and do some test prints to see how they come out.  Stay Safe!

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SmilerGrogan Senior Member • Posts: 1,253
Re: Can I use an light meter to get monitor brightness?
3

Maybe somone more knowledgeable than I can explain what needs to be onscreen to do the measuring.

But, according to the calculator here: https://www.translatorscafe.com/unit-converter/en-US/luminance/6-1/ 120 cd/m2 would measure at EV 10 on your light meter.

That translates to 1/60 at f/4 and ISO 100 according to the chart found here https://www.scantips.com/lights/evchart.html

However, if you're into fine art printing, you're better off if you buy a monitor calibration tool from a company like X-rite.

I assume you do all your editing in a windowless room with only a tiny, low-wattage bulb for a illumination, yes?

al404 wrote:

I also have an external light meter but the question is:

How do I know what correspond at 120 cd/mq?

pixelgenius
pixelgenius Senior Member • Posts: 4,209
Re: Can I use an light meter to get monitor brightness?
4

SmilerGrogan wrote:

Maybe somone more knowledgeable than I can explain what needs to be onscreen to do the measuring.

Sure. What's measured, cd/m2, white point and more has to be measured so an ICC profile can be produced that is used to produce a preview.

So there's zero reason anyone would futz with a light meter. One needs a Colorimeter, or a Spectrophotometer and software to actually measure what's necessary to build a display profile that defines device behavior for color managed previews. Simple.

SmilerGrogan Senior Member • Posts: 1,253
And There You Have It

Once again proving that thinking out loud in public is rarely a good idea.

But I do stand by my suggestion to edit in a dark room with only a nightlight for illumination.

Oh, and turn off the auto brightness adjustment. You can find it by going to System Preferences>Displays>Automatically adjust brightness.

So there's zero reason anyone would futz with a light meter. One needs a Colorimeter, or a Spectrophotometer and software to actually measure what's necessary to build a display profile that defines device behavior for color managed previews. Simple.

pixelgenius
pixelgenius Senior Member • Posts: 4,209
There You Have It
4

SmilerGrogan wrote:

Once again proving that thinking out loud in public is rarely a good idea.

Depends on the quality of the thinking.

But I do stand by my suggestion to edit in a dark room with only a nightlight for illumination.

That's a very good idea san's the nightlight: You can't have the environment too dark, it can be too light. Or during the day with an invention called curtains. Preferably room darkening. Black foam core is the photographers friend too.

There is this too:

http://lumita.com/site_media/work/whitepapers/files/calibrating_digital_darkroom.pdf

With the light output levels of current display technology, an ambient light level of 4 lux is an optimal compromise. While a lower light level would provide better results, it’s impractical. You need to be able to walk around your environment.

Oh, and turn off the auto brightness adjustment.

Yes! Since it invalidates calibration and the resulting profile used for producing a preview.

But using a Light meter for the task of calibration and profiling a display? Not necessary, not possible.

SmilerGrogan Senior Member • Posts: 1,253
Re: There You Have It

But using a Light meter for the task of calibration and profiling a display? Not necessary, not possible.

The OP was only asking about the light output of his monitor, not calibration...

…which points to a much greater problem; it would seem that any notion of color management is gradually disappearing from the discussion.
It’s the result of a rather arrogant form of photographic nihilism that has taken root in some of the forums.

pixelgenius
pixelgenius Senior Member • Posts: 4,209
There You Have It again
1

SmilerGrogan wrote:

But using a Light meter for the task of calibration and profiling a display? Not necessary, not possible.

The OP was only asking about the light output of his monitor, not calibration...

The topic and question: ”Can I use an light meter to get monitor brightness?”

The display needs a profile reflecting calibration for previews in color managed applications. That includes it's cd/m2 which isn't brightness, the gamut (measured RGB primaries), the TRC and the White Point. When done, the cd/m2, which isn't brightness IS measured as set. And more importantly, part of the profile that controls the preview of the image.

…which points to a much greater problem; it would seem that any notion of color management is gradually disappearing from the discussion.

The problem is ignoring color management and how applications produce previews that use color management. The problem is ignoring the fact calibration of a display both provide the cd/m2 desired, measures what the OP seeks and controls what and how he sees the image.

It’s the result of a rather arrogant form of photographic nihilism that has taken root in some of the forums.

Rather, the result of ignoring the facts of how displays produce previews in color managed applications while allowing the target of cd/m2 which is not brightness.

MrBrightSide
MrBrightSide Contributing Member • Posts: 868
Re: There You Have It again

I believe the disconnect may be the difference between Macs and PCs.

On some PCs you can set the brightness to specific numbers like 120 cd/m2. So the advice to set the screen to a particular number makes sense if it’s one PC user talking to another.

On all the Macs I’ve used there is only a slider so there’s no way to know where your cd/m2 is sitting.

pixelgenius wrote:

SmilerGrogan wrote:

But using a Light meter for the task of calibration and profiling a display? Not necessary, not possible.

The OP was only asking about the light output of his monitor, not calibration...

The topic and question: ”Can I use an light meter to get monitor brightness?”

The display needs a profile reflecting calibration for previews in color managed applications. That includes it's cd/m2 which isn't brightness, the gamut (measured RGB primaries), the TRC and the White Point. When done, the cd/m2, which isn't brightness IS measured as set. And more importantly, part of the profile that controls the preview of the image.

…which points to a much greater problem; it would seem that any notion of color management is gradually disappearing from the discussion.

The problem is ignoring color management and how applications produce previews that use color management. The problem is ignoring the fact calibration of a display both provide the cd/m2 desired, measures what the OP seeks and controls what and how he sees the image.

It’s the result of a rather arrogant form of photographic nihilism that has taken root in some of the forums.

Rather, the result of ignoring the facts of how displays produce previews in color managed applications while allowing the target of cd/m2 which is not brightness.

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