Instrument Spotlight SpectroDens

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This reserved article originally appeared in CHROMiX ColorNews Issue 67 on March 26th, 2019.

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This month's instrument focus is the Techkon SpectroDens pressroom spectrophotometer, written by Pat Herold, manager of CHROMiX technical services.


Technon SpectroDens

Contents

History

The Techkon SpectroDens has been a staple instrument around the pressroom for years. Always a well regarded instrument, its reputation for accuracy and durability has made it a preferred instrument for many consultants. It is now in its fourth iteration; the current model, which came out in April 2017, is the SpectroDens 4.

Techkon describes the SpectroDens as a "densitometer", but most people in the industry would refer to it as a spectrodensitometer, an instrument that measures spectral wavelengths to return density values. Using a spectrodensitometer to get density readings is sort of like using a vise to crack nuts - it is capable of so much more! Spectral readings view all the light that the human eye can see, so there are many applications for human perception. Additionally, the device can return colorimetric data such as Lab values as well as full spectral data, as I have written about in this newsletter.

A spectrodensitometer returning colorimetric and spectral data is functionally the same as a "spectrophotometer" - which ColorNews readers might be more familiar with.

A display on the top of the unit provides access to all the internal controls and shows the results of individual patch readings and built-in tests.

Example of SpectroDens display

The SpectroDens comes in 3 different versions depending on the functions in the instrument:

Ease of Use

Using the SpectroDens is a convenient and largely frustration-free process. These folks must have some kind of patent on the idea of an aperture tube that is formed into the edge of the instrument. The user can always see the patch that is being measured, whether in spot mode or scanning an entire row of colors. It's hard to describe how simple and intuitive this is. There is no need to fold down a part of the instrument to engage the measurement or use an aiming aperture when you're covering the patches with the instrument - you literally just point and click. Another great feature of the SpectroDens is its ability to communicate to a computer over Wifi; it’s rather convenient to be able to be several feet away from the computer when scanning charts. This also enables making spot measurements right on the press, since the device is wireless.

The battery life of the SpectroDens is much longer than one might expect; in our use, we almost never need to set the device aside to charge. It automatically goes to sleep when not in use, but readily wakes up when you click the measurement button. If you are plugging it into a computer with the USB plug to export measurements, the unit will also charge while being plugged into your computer. Finally, the SpectroDens’ small size and portability make it easy to handle and manipulate.

Speed

Techkon thinks highly of their scanning speed on this instrument. And I have found that it's rarely the speed of the instrument that is a limiting factor in how quickly you can measure. The speed of measurement largely depends on how fast you slide the instrument along the row without making human errors. Most handheld scanning instruments like this will have some natural limits to how fast you can scan without sliding off the row, or stopping on the wrong patch. We found the scanning speed to be comparable to or better than other hand-held instruments. For perspective, I scanned a single page of 960 patches in about five minutes.

Accuracy

Techkon has a long history of making quality instruments. The published specs reports an astonishingly small .03 difference using dE*a*b for inter-instrument agreement and a .30 dE*a*b for repeatability with the same instrument. (Delta E*a*b is a fancy way of saying “dE76”.) In our own in-house tests, we have seen our unit put out an average dE00 of .31 with a max dE00 of .70. Your results may vary according to how adept you are with sliding the unit, how big the patches are, how consistent your printing, etc.

Aperture

The SpectroDens generally comes with a 3 mm aperture, which is suitable for most modern printing applications. One can also choose to purchase a unit with a smaller 1.5 mm aperture at an additional cost. These smaller aperture sizes would not be suitable for coarse printing systems with lower dpi settings or some loose fabrics. In those cases, you would want an instrument that measures a larger area so as to get a more accurate representative sample of the color.

CHROMiX Measurement Module using X-Rite i1IO target reference


Measurement

All versions of the SpectroDens can measure using all four measurement modes: M0, M1, M2 and M3. Like the eXact, it's a treat to have an instrument that can offer polarized measurements in a handheld scanning package. Note that the Techkon measures in 10 nm increments from 400nm to 700nm. Other chart readers have a wider spectral range (see this article) for more details), but in practical use, one would be hard-pressed to come up with a convincing argument to say that the wider range of spectral bands is needed.

Charts

For its essential purpose (getting Lab readings from individual patch measurements), a chart isn’t needed. You don't need a chart since you can simply just choose and measure a small number of patches, one by one, and read measurement results off the back of the device. When it comes to using the SpectroDens for scanning large charts for profiling and the like, software solutions are not common. Techkon does supply their own software that can do this, but it is only available for Windows, and there is quite a learning curve to figure out how to make it all work.

The easiest way is to use the measuring module in Curve4 or the Maxwell Client, and then export the measurement to profile-making software. The CHROMiX measuring module allows for many different target definition references to be used. You can use targets that are made for your particular profile-creation software (for example: i1Profiler, CoPrA, Barbieri) and, in most cases, the SpectroDens will read these charts without any problem.

Software

Techkon provides a free SpectroConnect software, which is regrettably only available for Windows computers. The software allows the unit's measurement data to be transferred to a computer for a variety of uses, including measuring a media wedge. For those who are used to a wizard-like program that will walk you through the steps of measuring a profiling target, this is not the easiest software to understand or use, although it can serve as a connection module, firmware updater, and set of measurement tools.

Also available is Techkon's ExPresso 4 software. This is a printing workflow coordinator, where a printer can keep track of their print jobs, what press and color bar were used, as well as measuring conditions. This software is only available for the Premium version and costs several thousand dollars.

Of course, no Instrument Spotlight would be complete without us mentioning that we support this instrument in our Maxwell Client and Curve4 software packages.

Cross-Platform issues

As noted above, the Techkon software is only available on the Windows platform. Also, both wired and wireless connections on a Windows machine require a "TD Service" program to be installed and connected to, in order to talk to the instrument. It's not the simple USB plug-and-play that we have become familiar with in recent years. Fortunately, Techkon has provided some developers a more conventional USB driver connection for the Mac, which makes wired connection much more simple for Mac users.

Our Curve4 and Maxwell apps are available for Mac or Windows, but have the same restrictions in Windows as described above.

Conclusion

This is a great instrument. If you are fortunate enough to have one, then you will be pleased with your purchase for years to come. The one thing that prevents more people from owning a SpectroDens is the price; this is one of the better hand-held devices in the world today, and the price tag reflects that - the SpectroDens 4 Premium version is $7267 at CHROMiX.com. I've never known anyone who owned a SpectroDens and didn't love it. Once a company or a purchasing manager makes the decision to make the purchase, it becomes a dependable workhorse in the company for a long, time.

Thanks for reading,


Patrick Herold CHROMIX, Inc.



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