Variation in density while using 2 different instruments.

[Yuvaraju.V.]

Why does density reading from Techkon RS 800 and Eye one pro don’t match?
I have kept all other settings at identical but still the readings are different in all colors.
There is a deviation of 2.0 to 0.8. Kindly explain.

 

[gordo]

Why does density reading from Techkon RS 800 and Eye one pro don’t match?
I have kept all other settings at identical but still the readings are different in all colors.
There is a deviation of 2.0 to 0.8. Kindly explain.

There are many reasons why instruments don't agree. A few reasons are listed and explained and explained here:
Quality In Print: Top reasons why color instruments don't agree

best, gordon p

 

[Johu]

Hi,
putting aside the possibility of older devices not beeing in correct calibrated state, the main reason in my understanding for those two specific devices showing different readings is the fact that eye one does not have polarization filter. So the density reading on the eye one is not correct by nature, it is compensated on some software in order to give more "usual" density readings. The Lab values on both devices should be very close to one another though or otherwise they are not in good working condition.

 

[Greg Imhoff]

This is a normal and why we recommend choosing one instrument maker to standardize your shop with. Why? Filter sets are designed to specific NM (Nanometer) pick up bandwidth values so there are different optical specs and instrument designs.

1) Make certain your filter sets (47/B or Status T) match.

2) Calibrate each to a common calibration setting regularly.

3) Next be aware of a phenomenon known as "Non Inter Instrument Linearity".

• Different instrument makers may build with correct filter sets and operators run with common calibration points yet, still find varying density ranges on the same sheet due to "Non linear response."
• This may be when one moves away from preselected CMYK calibration points up or down and do not match because, each has a different optical design. Density values move away from the calibrated Density points without the same values as each unit is now seeing and reporting differently as each tool has its own unique pick up even if meeting ANSI or ISO specs ie: 45/0 or 0/45 optics and nanometer CMYK filter sets.
• So a 360 Ring Lens picks up differently from a 16 point array of Density filters set in a array of ring setting.
• Some instruments may also be seen reading higher values ie: 2.05 K vs. the another recording @ 1.90. This ability may be described as Dynamic Range.
• In Density "less (light) reflected is more (Density) calculated algebraically from the Logarithmic value of light. This may sound more complicated than it is basically the more powerful the optical pick up, the broader range of Density and control.

When in doubt standardize.
Sincerely,
Greg Imhoff
President GRIPdigital, inc. & Director EPG Color Solutions
(800) 394 - 7130 - office
(708) 557 - 2021 - cell
Skype: gregimhoff
Print Properties Committee Member and GRACoL G7 Expert
Essex Products Group | Integrated Color Control Systems

There are many reasons why instruments don't agree. A few reasons are listed and explained and explained here:
Quality In Print: Top reasons why color instruments don't agree

best, gordon p