Re: [colorvision_group] No Variable Natural Light - with Reply
2006-04-17 by CDTobie@aol.com
In a message dated 4/16/06 5:52:55 PM, davedoughman@... writes:
Sounds like an ideal digital photo room should have no outsided
windows (the light always varies) and all light in the room should be
consistant and quite dim.
Thats correct. I always surprises me with the amount of effort and expense that photographers are willing to put into gear, that they are so resistant on the point of studio lighting.
This leads to several questions to help
improve my set up.
When real life's limitations gets in the way of a perfect digital dark
room set up how should we prioritize those things we can control?
Drapes and blinds are a good start... being willing to use them is a good followup. Color correction work is not a day at the beach. I recently called the ColorVision Europe technical staff into the conference room I was using as an office. I pointed out the significant mismatch between an image on my Powerbook, and a print I had just made on an R2400, and asked them to diagnose the problem. One of them had been through this with me before, and suggested (correctly) that it was lighting related.
This was in a large room with windows across both ends, that were fully blacked with metal exterior shutters (got the love those EuroShutters), and a large window on one side that was small in relation to the size of the room, but floor to ceiling and probably 12 feet wide. The sun had crept around and was shining in that window onto the white sill (several feet deep, forming a kind of bay) in the window, and bouncing from there to the white wall behind me as I worked at the conference table.
So I asked them to estimate which of the five levels of ambient light (from Spyder2PRO v2.2) the room currently had, in relation to my monitor, and the one who was a professional photographer suggested it was between a 2 and a 3, in other words, right in the middle of where photo correction should be. I ran the ambient light measurement function, and the Spyder read the light reflecting off the wall behind me, and registerd level 5, which means extra high, uncontrolled lighting, unfit for any type of color managed work. And this was with no lights on in the room, just the intense reflected sunlight from one window.
Closing the external blinds on the one unshuttered window brought the light level down to a very dim, color managed state, and the screen and print matched nicely, once our eyes had adapted. Our eyes are vary adaptive, thus easily fooled by uncontrolled conditions.
1. When/under what conditions should we calibrate our monitor? At
night with all lights off and curtins drawn, under low lighting room
light with no light falling directly on the monitor, day time but no
room lights on at all? What if we work both day and night hours?
We're looking at more flexible options than demanding a single, onvarying situation; but the correct answer is a single unvarying condition. Use the ambient light check to define what levels each of your conditions achieves, decide which of these you can live with, calibrate to the most typical, and then decide if multiple calibration targets, without front panel hardware adjustments between them, better serve your needs.
2.As most of our digital printing rooms will have some lights on when
we work what should be our goals?
No one is saying you shouldn't have light on, just that you shouldn't have American Office Building levels of light on, and that what you use should be consistant, and in the low to moderate range, depending on your monitor type and chosen monitor luminance.
- No light falling directly on the monitor screen?
Thats a good start, oveheads directly on the screen are hard on the eyes as well as bad color management.
- Fairly dim room lighting?
Right... use Spyder2PRO v2.2 to test this.
- Color temp of the room lighting?
Quality, full spectrum lighting in the 5000k to 6500k range (daylight colored, not extremely warm, not extremely cool, shows colors well, not too bright...)
Similiar to the lighting temp we
expect the prints to be viewed?
That would be a proofing light choice, for checking prints for a given display lighting. I wouldn't recommend using really yellow cheap incandescent lights in your studio, even if your clients tend to hang your work under such lights, but I would recommend such a light as an option in your proofing area, for checking prints under warm light.
Use a D50 light for critical color
evaluation?
A good choice, for general lighting, and proofing lighting, to avoid a big discontinuity between the two... having warm and cool lights available for proofing as well is a good idea.
A mix of D50 and standard lamps?
There is no such thing as standard lamps; screaming yellow incandescent, and cool blue fluorescent are the two most common, and they are both impossible to judge color well under, and way out of the centeral range of light color. My wife knows perfectly well that she can't tell teal from blue from purple under the incandescent lights in our closet, and brings clothes out into the bedroom to view them under the Ott-Lite I keep on the bedside stand to tell what color they really are.
- How long after printing an image should we wait to do a critical
evaluation (ink drying time - min. & ideal).
Canon and HP dyes on gloss, in humid conditions: up to 24 hours would be advisable. Ultrachromes on matte: immediately is fine, everything else tends to fall in between.
Under lighting conditions
we expect the print to be viewed when shown?
A wide range, which is why using low metamerism ink/paper combos is best, and choosing shadow densities that work well for a range of luminance levels is appropriate.
- If we don't know/can't control viewing conditions for the print what
color temp/evaluating method seems to be a good standard to use?
Middle of the road on both counts: medium light color (5000 to 6500k) and moderate brightness (older prepress boxes are often quite dim, direct daylight is way bright, something in between) so that you are in the middle of the sweetspot. I recently made a large print of a rainbow over Zurich, where I adjusted the shadow detail to make a silhouette-like dark area out of two people huddled under an umbrella in the forground. A friend took the print to a large window, let direct sun pour in on it, and commented that the people under the umbrella were Asian. I had noticed that in the original image, but had thought it was eliminated in the print, but that depends on the viewing luminance... we can't control everything.
3. How often should we realistically recalibrate our monitors if we
want good consistant color work?
Monthly is certainly reasonable...
4. What else should I have asked?
More on that later, I don't want to exceed the max file size for posts!
C. David Tobie
Product Technology Manager
ColorVision Business Division
DataColor Inc.
CDTobie@...
www.colorvision.com