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Frequently asked questions
Why won’t the lamp light?
Usually caused by loss of calibration, or misuse and
resulting in misalignment of base plate. The lamp itself is usually OK. IQ units have
error checking in the software. When an error is detected, the lamp driver is turned off,
and remains off until the error is corrected. This is to prevent erroneous readings from
occurring.
The light spot reflecting off the target webbing when the unit is misaligned
will give
erroneous readings. Possible solutions include realignment and/or resetting the unit to
its Default (DFLT) settings. (see other references to DFLT)
Units in poor condition should be sent in for servicing
to correct the conditions that lead
to the occurrence of error messages. The densitometers must be in perfect working
condition in order to be able to be calibrated correctly.
Can wrong base values give an ERROR message?
Yes, occasionally the wrong base
values (ones that are too high) are stored and thus cause RF (Relative) densities to read
wrong. Review the manual for proper use of base.
Should I clean the calibration plaque before using it?
Calibrating to an unclean
calibration plaque can change your reading by 0.10D or more. Clean the plaque with
window cleaner prior to each use. Do not trust your eyes to judge if a plaque is clean.
The densitometer can “see” smudges that you can miss. Smudges on the white or zero
spot of the plaque are read by the densitometer as an increased density, while smudges on
the black spot reduce the density.
How can I match two densitometers?
After calibrating to the calibration plaque, color
response of the densitometer can differ from other densitometers. Color response is not a
calibration; it depends on the filters and the optics of a densitometer. As no two
densitometers respond to color exactly alike, do not judge one against another. If color is
in dispute, rely only on an approved color standard such as a “T ref” available from
Tobias Associates (see parts list).
A densitometer with minor variance can comply with the color standard by means of
the SLOPE program. Refer to the SLOPE instruction sheet.
How can I convert my 3/16” aperture unit to a 1/16” unit?
Units with 1/16” aperture
are useful in reading the narrow control strips. Units thus converted are designated with
the letter “A” at the end of the serial number. The pitfall is confusing “aperture” with
“target”. Do NOT attempt to convert a 3/16” aperture unit to a 1/16” unit by simply
changing the target. The sizing of the light spot originates within the optic head, and has
such, this conversion has to be done here at the factory.
