Digital BW, The Print

zonepeter wrote:

>My densitometer arrived today without calibration plaques.  I have a 
>Kodak Q60 (IT8) reflection target.  I was able to locate a web site 
>with densities for the gray scale on the bottom, including averages 
>for the d max and d min from 16 different charts they had tested.  
>I used these values and calibrated the densitometer.  Based on this, 
>I am getting readings that seem reasonable.  (EEM 1.64 dmax and HPR 
>at 1.72)  
>Is this a fairly accurate way to go or should I bite the bullet and 
>buy the calibration plaque.  I will be using the densitometer to 
>build curves with QTR or IJC/OPM.
>
>Thanks,
>Peter 
>
>  
>

Maybe it is wiser to find several good pieces of black and white 
ceramic. Take them with you to some local (offset) printshops and check 
whether they are  below or above their tiles in measurements with their 
densitometer. It will tell you which are good and the limitation of your 
or their meter on Dmax. To check the linearity of the densitometer you 
better get a true B&W paper based step wedge. You could check it with 
the printshops densitometers too and it is less likely to fade in time.

The IT8 ones are color paper and they fade in hue and density, average 
numbers from the web are a risk too, an IT8 target should have a batch 
measurement table somewhere, check the number and date on the target and 
do a search. If it isn't too old you will find the numbers somewhere, if 
not consider the target as being too old.

Ernst