5000 K bulbs

[Repairguy]

are shops in the printing industry still using the 5000 k bulbs
on cpc tables or color tables what are the best strips to test the bulbs
if so what is the bulb company and wattage of bulb

 

[rich apollo]

Depends on the installation.

GTI and JustNormlicht are the largest manufacturers of lighting for graphics.

Solux seems to be the biggest for photographers and art installations.

 

[Cornishpastythighs]

we are indeed still using 5000K to view colour in all our light booths. We have GATF test strips in all our booths, they stick inside the viewing booth and when the light is no longer true 5K stripes appear on them and its time to change bulbs

 

[meddington]

Although a poor color temperature is usually a good indicator that a bulb is out of tolerance, color temp measurement by itself is insufficient at
defining quality viewing conditions.
ISO 3664, the official viewing conditions standard, defines brightness, chromaticity (from which the 5000K temp is derived from D50), color rendering index, metameriam index, and uniformity, among others. So although color temp strips are a quick way to tell you your lighting doesn't conform, they fail to tell the whole story. A better approach is mesurement with an i1 spectro in ambient mode with i1Share, or better yet, BabelColor ct&A, though you'd need a spectroradiometer to get the full story. Lighting booth manufacturers aim at iso3664 when designing their products, but it can be very tricky to design your own conforming lighting.

 

[Bob_McC]

The Problem with Metameric Strips as Compliance Indicators

The Problem with Metameric Strips as Compliance Indicators

The use of metameric strips (like the ones from GATF) to verify that a viewing system is still 5000K or in compliance with ISO 3664 specifications is not recommended for the following reasons:

The two colors are designed to visually match under specific spectral power distributions, rather than color temperatures, so it is possible to see a closer match at a color temperature of 7500K than at 5000K.

The strips do not indicate differences in light intensity, surround conditions, light evenness or excessive glare. We tell folks that the GATF strips are great tools at telling you that your viewing system is not appropriate for critical color matching (if those two strips do not match, you definitely have a problem with color rendition), however even if they do match, there are many ways that the viewing system can still be out of spec.

To answer your initial question, yes 5000K is still whats being used for critical color viewing in the printing industry. In fact the standard was just re-published this year with D50 as the standard light source.

Here is a one page summary of the key elements of the viewing standard (if this link works.

http://files.gtilite.com/graphic_arts/specifications/What%20is%20the%20Viewing%20Standard-ISO%203664.pdf

Bob

 

[gordo]

[SNIP}
To answer your initial question, yes 5000K is still whats being used for critical color viewing in the printing industry.

To be clear - it's not about "critical color viewing" it's about every one in the production process viewing images under the "same" viewing conditions - hence, perhaps, eliminating one variable.

gordo

 

[Bob_McC]

That's very true, Gordo.

Consistent appearance of the colored image through out the production process is the greatest benefit that the ISO standard can deliver. The other key benefit - an environment that is optimized to allow the press operator to detect color differences between an approved proof or sign-off sheet and the latest pull from the press run - is also very helpful to the printer.

Bob

 

[edwinb]

The just Normlicht color communicator has electronic control of the bulbs allowing them to be adjusted to very exact match.

This does give the closest visual match I have ever seen between a calibrated display (Eizo) and a proof (iso 39)

having the adjustability, rather than trying to get the best bulb, is perhaps a better way to go

Edwin

 

[Bob_McC]

Variable light intensity is great for soft-proofing

Variable light intensity is great for soft-proofing

If Repairguy is implementing soft-proofing in his press room then a variable intensity viewer would be almost a necessity.

If he is simply setting up a lighting environment, or simply relamping his light fixtures over the pres console, then adjustable intensity would be an expensive feature that would not deliver much benefit to him.

** commercial break **
We (GTI) have many customers who daily achieve superb visual matches between monitors and printed copy using our Softview variable intensity viewer or our MCVE/SP on-press soft proofing systems
** back to the program**

Generally speaking, the amount of investment that Repairguy needs to place in his pressroom viewing lights is a function of the nature of their work and the nature of their clients. Even though GTI has been promoting the benefits of full compliance to the ISO standard for many years (35+), we know that there are many printers who can achieve great success without meeting all the requirements of the standard. A set of D50 lamps may be all that is needed to give the press operator the color rendition and intensity he needs to run the job.

As the quality requirements rise, the better the case for tight compliance to ISO 3664.