Datacolor User to User Support Group.

Hello all,

I have just calibrated my monitor for the first time with this new
hardware. 

The help states that 2.2 Gamma 6500K seems to be the most frequently
used target.

I do have questions about the monitor target temperature that I cannot
seem to answer using the provided documentation.

How does the target temperature relate to the lighting conditions of
the room you work in?

6500K usually represents outside afternoon lighting conditions so a
fair amount of light in the room I would think.

If all I have is incandescent lights far away in the room or I turn on
a low powered halogen light that bounces off the ceiling and only a
small amount reaches the work areas, what kind of target would be
better suited?

If someone could please clarify how one chooses the color temperature
used in monitor targets I would be very happy. :O)

Thanks,
Pierre

>Hello all,
>
>I have just calibrated my monitor for the first time with this new
>hardware.
>
>The help states that 2.2 Gamma 6500K seems to be the most frequently
>used target.
>
>I do have questions about the monitor target temperature that I cannot
>seem to answer using the provided documentation.
>
>How does the target temperature relate to the lighting conditions of
>the room you work in?
>
>6500K usually represents outside afternoon lighting conditions so a
>fair amount of light in the room I would think.

5200°K is more close to natural sunlight. 
Therefore, I would suggest that you standardize 
on 5000°K. and 2.2 Gamma. 6500°K is too blue.

>
>If all I have is incandescent lights far away in the room or I turn on
>a low powered halogen light that bounces off the ceiling and only a
>small amount reaches the work areas, what kind of target would be
>better suited?


You can buy 5000°K fluorescent tubes and daylight 
fluorescent replacement "bulbs"  at stores such 
as Home Depot. All the lighting in my studio 
where I do my color matching of prints is 5000°K.

The color temperature in which you do your work 
is extremely important. Once you decide on a 
color temperature, take a photo that contains red 
and observe it under say a 5000° K light. Then 
look at it under a lamp that has an ordinary 
incandescent bulb. You will see a tremendous 
difference.

And just as important, don't forget when you are 
working with color to set the background of your 
monitor to medium gray.

Gene

Hi Gene,

The room I work in has very little lighting and none of it is
fluorescent. Is there such a thing as daylight incandescent bulbs?

Thanks for the lighting suggestions.

Pierre

--- In colorvision_group@...m, Eugene Coggins
<elcoggins@...> wrote:

>
> >Hello all,
> >
> >I have just calibrated my monitor for the first time with this new
> >hardware.
> >
> >The help states that 2.2 Gamma 6500K seems to be the most frequently
> >used target.
> >
> >I do have questions about the monitor target temperature that I cannot
> >seem to answer using the provided documentation.
> >
> >How does the target temperature relate to the lighting conditions of
> >the room you work in?
> >
> >6500K usually represents outside afternoon lighting conditions so a
> >fair amount of light in the room I would think.
> 
> 5200°K is more close to natural sunlight. 
> Therefore, I would suggest that you standardize 
> on 5000°K. and 2.2 Gamma. 6500°K is too blue.
> 
> >
> >If all I have is incandescent lights far away in the room or I turn on
> >a low powered halogen light that bounces off the ceiling and only a
> >small amount reaches the work areas, what kind of target would be
> >better suited?
> 
> 
> You can buy 5000°K fluorescent tubes and daylight 
> fluorescent replacement "bulbs"  at stores such 
> as Home Depot. All the lighting in my studio 
> where I do my color matching of prints is 5000°K.
> 
> The color temperature in which you do your work 
> is extremely important. Once you decide on a 
> color temperature, take a photo that contains red 
> and observe it under say a 5000° K light. Then 
> look at it under a lamp that has an ordinary 
> incandescent bulb. You will see a tremendous 
> difference.
> 
> And just as important, don't forget when you are 
> working with color to set the background of your 
> monitor to medium gray.
> 
> Gene
>

David,

How do you guys evaluate the intensity of your lighting?

The reason I ask is that I have never done studio work as most of my
images are in natural light outside so I do not possess this experience.

Does it mean that I need to get an incident light meter to measure it
and would this thing give me K units?

Thanks for the explanation,

Pierre

--- In colorvision_group@yahoogroups.com, CDTobie@... wrote:
>
> 
> In a message dated 11/4/06 11:47:57 AM, ve2caz@... writes:
> 
> 
> > How does the target temperature relate to the lighting conditions of
> > the room you work in?
> > 
> 
> It does not relate directly to the color temperature of your ambient 
> lighting; as lighting gets dimmer, your color cones become less
effective, and your B&
> W rods do more. The rods see quite blue, so to compensate the
monitor must be 
> more yellow. Thats why the more yellow 5000k is used in low ambient
light 
> conditions, and 6500k is used in moderate ambient light conditions.
So choose your 

> monitor whitepoint based not on your ambient light's color, but on its 
> intensity.
> 
> C. David Tobie
> Product Technology Manager
> ColorVision Business Division
> DataColor Inc.
> CDTobie@...
> www.colorvision.com
>

>Hi Gene,
>
>The room I work in has very little lighting and none of it is
>fluorescent. Is there such a thing as daylight incandescent bulbs?

Yes Pierre. But I found the incandescent bulbs 
are usually poor.  I recommend low energy 
fluorescent "BULBS" that replace the incandescent 
bulbs. Currently at home improvement stores one 
can by these replacement "bulbs" that look like a 
miniature spiral fluorescent tube. They typically 
consume 27 watts and produce the equivalent light 
of a 100 watt incandescent bulb. However, 
carefully inspect the packaging to determine the 
color temperature. I use a lot of long 
fluorescent tubes in ceiling lights and on my 
desk where my computer resides. However, in a few 
table lamps, I use the replacement fluorescent 
bulbs mentioned above.

Another very important unit of measure is the 
color rendering number. It is on a scale of 0 to 
100. You can have a light that has a average 
distribution of color temperatures that is not 
uniform. In other words, there can be spikes in 
the color spectrum that will still yield the 
average desired color temperature. So the closer 
the color rendering is to 100, no spikes, the 
better. Typically somewhere between 90 and 95 is 
quite acceptable.

Phillips makes a fluorescent tube that is called 
"Natural Sunshine." it is 5000°K and has a color 
rendering of 92. They also make a tube that is 
called "Daylight Deluxe" It has a color 
temperature of 6500°K but also has a poor color 
rendering of 84. The down side of all this is 
that these Natural Sunshine tubes cost twice as 
much as the regular Cool White.

I just purchased from Home Depot a bunch of 
fluorescent bulbs for $7 each made by N:Vision, 
manufactured in GA. They produce 100 watts 
equivalent light yet consume only 27 watts. They 
are labeled "Daylight." They are also labeled as 
having a color temperature of 5500°K.

The whole purpose of calibrating your monitor is 
that you hope that what you see on your monitor 
is what comes out of your printer. While it can 
never be exact, is can be very close. If you see 
a color image on your screen and then look at the 
print under a poor light, it will not match. So 
matching the color temperature of the ambient 
lighting you are working in to that of the 
monitor is very important. Also be aware that the 
print should dry for at least 12 hours or more 
before color matching.

One word about the Spyder2 Pro. I found when 
calibrating my monitor with this device, to be 
very conservative on the manual brightness 
setting. If the monitor brightness is set too 
high, the colors on the monitor will appear very 
bright but not in the print.

Hope all this helps,

Gene

Gene,

Thank you very much for this information. This is the kind of thing I
was looking for. I will be making a stop at various hardware stores in
my area to look for such lamps and bulbs.

Cheers,
Pierre

--- In colorvision_group@yahoogroups.com, Eugene Coggins
<elcoggins@...> wrote:

>
> >Hi Gene,
> >
> >The room I work in has very little lighting and none of it is
> >fluorescent. Is there such a thing as daylight incandescent bulbs?
> 
> Yes Pierre. But I found the incandescent bulbs 
> are usually poor.  I recommend low energy 
> fluorescent "BULBS" that replace the incandescent 
> bulbs. Currently at home improvement stores one 
> can by these replacement "bulbs" that look like a 
> miniature spiral fluorescent tube. They typically 
> consume 27 watts and produce the equivalent light 
> of a 100 watt incandescent bulb. However, 
> carefully inspect the packaging to determine the 
> color temperature. I use a lot of long 
> fluorescent tubes in ceiling lights and on my 
> desk where my computer resides. However, in a few 
> table lamps, I use the replacement fluorescent 
> bulbs mentioned above.
> 
> Another very important unit of measure is the 
> color rendering number. It is on a scale of 0 to 
> 100. You can have a light that has a average 
> distribution of color temperatures that is not 
> uniform. In other words, there can be spikes in 
> the color spectrum that will still yield the 
> average desired color temperature. So the closer 
> the color rendering is to 100, no spikes, the 
> better. Typically somewhere between 90 and 95 is 
> quite acceptable.
> 
> Phillips makes a fluorescent tube that is called 
> "Natural Sunshine." it is 5000°K and has a color 
> rendering of 92. They also make a tube that is 
> called "Daylight Deluxe" It has a color 
> temperature of 6500°K but also has a poor color 
> rendering of 84. The down side of all this is 
> that these Natural Sunshine tubes cost twice as 
> much as the regular Cool White.
> 
> I just purchased from Home Depot a bunch of 
> fluorescent bulbs for $7 each made by N:Vision, 
> manufactured in GA. They produce 100 watts 
> equivalent light yet consume only 27 watts. They 
> are labeled "Daylight." They are also labeled as 
> having a color temperature of 5500°K.
> 
> The whole purpose of calibrating your monitor is 
> that you hope that what you see on your monitor 
> is what comes out of your printer. While it can 
> never be exact, is can be very close. If you see 
> a color image on your screen and then look at the 
> print under a poor light, it will not match. So 
> matching the color temperature of the ambient 
> lighting you are working in to that of the 
> monitor is very important. Also be aware that the 
> print should dry for at least 12 hours or more 
> before color matching.
> 
> One word about the Spyder2 Pro. I found when 
> calibrating my monitor with this device, to be 
> very conservative on the manual brightness 
> setting. If the monitor brightness is set too 
> high, the colors on the monitor will appear very 
> bright but not in the print.
> 
> Hope all this helps,
> 
> Gene
>

So my options are:

1° Buy 5000K bulbs
   Set the monitor target at 5000K

or

2° Measure the light intensity using this new feature
   Set the monitor target based on the measure

Now how do I relate candle/meter^2 measures to monitor target values?

Thanks,
Pierre

--- In colorvision_group@yahoogroups.com, CDTobie@... wrote: 

> There is a light intensity measurement function in the recent versions 
> of Spyder2PRO, available for download from the colorvision website.
>
> K is color temperature, we're talking luminance, which is candelas
> per meter square.
> 
> C. David Tobie
> Product Technology Manager
> ColorVision Business Division
> DataColor Inc.
> CDTobie@...
> www.colorvision.com

I appreciate you taking the time to explain it to me and I really want
to get this right.

Assumptions:

1) Bulb contribution

5000K rated bulbs determine the color temperature of emitted white
light regardless of its intensity.

These bulbs are useful in the context of examining prints calibrated
for white at 5000K.

2) Illumination contribution

Illumination relates to the intensity and distance of a light source.

Relative illumination (light intensity in candelas / meter^2) measured
at the monitor represents illumination minus distance loss.

I can measure this (in candelas / meter^2) using the provided colorimeter.

If the colorimeter is pointed at the monitor, I am measuring the
monitor contribution whereas if it is pointed away from the monitor I
am measuring the contribution of the light source.

Both sources of light contribute to the overall illumination affecting
the eyes.

Rods (B&W vision) are more sensitive to low illumination whereas cones
(color vision) require more illumination.

To properly assess color one needs enough illumination so that eyes
use mostly cones.

With high levels of ambient light one should select higher temperature
monitor targets where as in low levels of ambient light one should
select lower temperature monitor targets.

Questions:

Assuming the colorimeter is pointed away from the monitor how much
illumination is required i.e. what would be a good interval measured
in candelas / meter^2 for vision to mostly use cones?

Given measure X candelas / meter^2 within this interval a monitor
target of 5000K should be used, right?

For some reason I am being very "dense" about this but I am trying to
ensure I properly setup my environment to make the most of my color
vision purchase.

Thanks,
Pierre


--- In colorvision_group@yahoogroups.com, CDTobie@... wrote: 
> Candelas per meter square IS the monitor target value; which is
related to 
> suggested ambient light levels (or ambient light levels are related
to suggested 
> target monitor values, you can adjust either).
> 
> Using 5000k lights and calibrating to 5000k will not solve the
issue: lots of 
> 5000k ambient light would still require a monitor temperature of
6500k, since 
> it would stimulate the rods less and the cones. A tiny amount of 6500k 
> ambient light would require you calibrate the monitor to 5000k. Do
you begin to see 
> that monitor temperature and ambient light temperature are unrelated
items? 
> The eye is variable in how it perceives color, so the monitor must
be adjusted 

> for that, not the color of that light.
> 
> C. David Tobie
> Product Technology Manager
> ColorVision Business Division
> DataColor Inc.
> CDTobie@...
> www.colorvision.com
>