Digital BW, The Print

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

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

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, Ernst Dinkla
<E.Dinkla@c...> wrote:

> zonepeter wrote:
 
> >My densitometer arrived today without calibration plaques. 


 
 
> 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.

...aside from the possibility of fading,a paper target's accuracy will
deteriorate due to handling and normal use, including the necessary
direct contact that's made with the densitometer--so  such a standard
is not likely to be relaible for long-term use (i.e., used for
frequent recalibration). If the densitometer was advertised as "with
plaque" but did not include it, I'd certainly complain to the seller
and demand some compensation.

Phil

Thanks Ernst and Phil.  Sounds like the best bet is to buy the plaque.
The plaques weren't advertised with the densitometer, but it was a 
good enough deal to make it worth it anyway.  Thanks again.
Peter


--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "Phil Rose" 
<pjrose@f...> wrote:
> 
> --- In DigitalBlackandWhiteThePrint@yahoogroups.com, Ernst Dinkla
> <E.Dinkla@c...> wrote:
> 
> > zonepeter wrote:
>  
> > >My densitometer arrived today without calibration plaques. 
> 
> 
>  
>  
> > 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.
> 
> ...aside from the possibility of fading,a paper target's accuracy 
will
> deteriorate due to handling and normal use, including the necessary
> direct contact that's made with the densitometer--so  such a 
standard

> is not likely to be relaible for long-term use (i.e., used for
> frequent recalibration). If the densitometer was advertised as "with
> plaque" but did not include it, I'd certainly complain to the seller
> and demand some compensation.
> 
> Phil

--- In DigitalBlackandWhiteThePrint@yahoogroups.com, "zonepeter" <zonepeter@a...> 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.

Is your densitometer an X-rite?

My X-rite 414 (status A) needs a cal plaque with a d-max around 1.8. An X-rite status A cal plaque only has white, black, and gray spots. The black is 1.8. If you try to cal it with something around 1.6, it actually decides it's a status E, status I, or status T instrument (I am not making this up) and the firmware goes into status E/I/T mode. Cal then demands you meter the magenta, cyan, and yellow spots of the plaque for a status E/I/T instrument. And the ned result is a really messed up, non-linear instrument.

It took hours on the phone with x-rite tech support to get this resolved.