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Author Topic: Gallery is 150lux 3500Kelvin but monitor?  (Read 2241 times)

Yorg1001

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Gallery is 150lux 3500Kelvin but monitor?
« on: May 19, 2016, 06:23:11 am »

Hi folks, this is my first OP here, please forgive if this has been covered, as it probably has, but didn't quite see answer in a scan of recent stuff.

Just new to printing and have yet to even set up my p800.
I want to make prints for a gallery which illuminates prints at 150 lux and uses 3500 kelvin solux lamps.

I have both a colormunki photo and a Spyder5studio. They disagree on room luminance and therefore monitor brightness, but that's another story.
These devices prompt for calibration to either D65 but can do D50, which i understand to mean something analogous to 6500 and 5000 Kelvin respectively.
Let's say I use D65.
The coolest solux lamp I can buy to evaluate my test prints coming off the printer is rated at 5000 kelvin, and that would presumably get me close to matching my monitor's colour temp if I'm using D50.
But the gallery is lit with 3500K.
So, I could buy a 3500 kelvin solux lamp and match my test print viewing conditions to the gallery, but then I am nowhere near the monitor's D50 setting.

So I am confused. My understanding is that in order to manage the colour in the whole workflow I would need to have a consistent colour temperature rendering from monitor, through viewing conditions of my test prints and ultimately to the gallery viewing conditions.

But I don't think I can calibrate my monitor that warm (3500K).

I can't square this circle.

Can you help?
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torger

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Re: Gallery is 150lux 3500Kelvin but monitor?
« Reply #1 on: May 19, 2016, 07:04:17 am »

Probably others around that can give you a better and more informed answer.

My take on it is however not to worry that much. I would use the standard setup with 6500K on screen and ~5000K viewing lamp and design the prints under that light.

Moving to 3500K should mostly just be about chromatic adaptation, the prints should not change drastically in look. That is a print that works in 5000K should work well also in 3500K. Maybe there are people that produce different prints for 3500K and 5000K but it seems to me to be overkill...?
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digitaldog

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Re: Gallery is 150lux 3500Kelvin but monitor?
« Reply #2 on: May 19, 2016, 10:09:37 am »

The only numbers that are meaningful are those that produce a visual match from (in many cases print) to screen.


https://luminous-landscape.com/why-are-my-prints-too-dark/


And

Why are my prints too dark?
A video update to a written piece on subject from 2013
In this 24 minute video, I'll cover:

Are your prints really too dark?
Display calibration and WYSIWYG
Proper print viewing conditions
Trouble shooting to get a match
Avoiding kludges that don't solve the problem


High resolution: http://digitaldog.net/files/Why_are_my_prints_too_dark.mp4
Low resolution: https://youtu.be/iS6sjZmxjY4
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http://www.digitaldog.net/
Author "Color Management for Photographers".

Doug Gray

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Re: Gallery is 150lux 3500Kelvin but monitor?
« Reply #3 on: May 19, 2016, 12:26:27 pm »

Another aspect of getting a monitor/print match is the low level of illumination. 150 Lux will illuminate a print to the same intensity as roughly 40 to 45 cd/m^2.   The equation is (white reflectance)*Lux/Pi. White reflectance is typically .85 to .9. That's a pretty dim level. There is also a psychological aspect to color temperature perception with brighter light at the same actual CCT appearing to be more reddish.
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Yorg1001

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Re: Gallery is 150lux 3500Kelvin but monitor?
« Reply #4 on: May 19, 2016, 10:36:25 pm »

Thanks for the replies.
I will definitely check out the link, DigitalDog

Doug,
What you say is quite intriguing, and perhaps you can shed some light on this also:
I have a lux meter which reads 250lux at my desk where I am viewing prints, which is right next to may monitor.
The colormunki I have reads this light level and want to calibrate the monitor to 80-90 cdm2.
The Spyder5Elite puck recommends 200cdm2.
The support people at Datacolor said that I have a very bright environment and the lux and cdm2 numbers are essentially the same - meaning that if I have 200lux or so on the desk then the monitor is appropriately bright at 200cdm2.
(At 200cdm2 the monitor looks quite bright.)

What are your thoughts on the brightness recommendations of these two instruments.
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Doug Gray

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Re: Gallery is 150lux 3500Kelvin but monitor?
« Reply #5 on: May 20, 2016, 12:31:54 am »

Thanks for the replies.
I will definitely check out the link, DigitalDog

Doug,
What you say is quite intriguing, and perhaps you can shed some light on this also:
I have a lux meter which reads 250lux at my desk where I am viewing prints, which is right next to may monitor.
The colormunki I have reads this light level and want to calibrate the monitor to 80-90 cdm2.
The Spyder5Elite puck recommends 200cdm2.
The support people at Datacolor said that I have a very bright environment and the lux and cdm2 numbers are essentially the same - meaning that if I have 200lux or so on the desk then the monitor is appropriately bright at 200cdm2.
(At 200cdm2 the monitor looks quite bright.)

What are your thoughts on the brightness recommendations of these two instruments.

First, Lux and cd/m^2 are different animals.  Lux is a measure of the intensity of an illuminant hitting a surface. cd/m^2 is the intensity of the light either being reflected from a surface or, emitted from a surface as in a monitor. A perfectly reflective surface that reflects, in all directions equally, all of the light that hits it, will have the following property. The reflected light is the Lux divided by Pi.

It depends on the purpose. Higher cd/m^2 makes it easier to see small color variations. But if you are trying to soft proof and match what you see on a monitor to a print then you need to match things. Traditionally, prints are viewed under 500 Lux with D50 or something close to D50 which is close to but not exactly the same as 5000K black body color. Solux lights are close. 500 Lux D50 will give a good match to monitors calibrated at roughly 165 cd/m^2 that are also set to D50 when soft proofing and setting the "paper color" check box.  But this is only true if your print paper has no significant UV brightener. Otherwise you may get a better match with a slightly higher monitor CCT. Perhaps 5500K or so. Personally, I prefer running my monitor at D50 and not using papers with OBs. I find D65, which is widely used, way too blue.

Andrew (Digitaldog) has some very good videos on this and, while I use a slightly different approach to matching monitor proofs and prints, his approach is very good, accomplishes the same thing, and I really haven't come across anything better on the web. Let alone for free.
« Last Edit: May 20, 2016, 12:37:00 am by Doug Gray »
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