Digital BW, The Print

Michael King schreef:
> Paul,
> 
> I see similar low paper white "a" values with two spectros.
> Both read just above 0. But I see "b" values about 0.8 (310g), lower than
> Ernst.
> 
> I wish there was some way to recalibrate these spectros without sending them
> off to Xrite.
> You should be able to just buy /install a new white tile and some software
> should do the re-calibration for you.
> Or are these white tiles really expensive and its cheaper to recalibrate the
> exisiting one ?
> 
> Mike

To get some references I checked the paper white measurements in the 
Aardenburg test results:

William Turner 310 gsm with UV included:
Lab 95.9 0.2 2.3

I guess that it is measured on a black tablet, my results are:

310 gsm
Lab 95.27 0.42 2.55 on a black tablet
Lab 95.69 0.68 3.06 on a stack of William Turner

180 gsm
Lab 94.27 0.28 1.34 on a black tablet
Lab 95.46 0.73 2.36 on a stack of William Turner

Paper has no OBA so comparable to Canson Rag Photographique, differences 
between batches and age of the paper probably more important than the 
differences between the spectrometers.

"a" not really high with the black tablet measurements and UV included, 
the same method I used for the CRP Lab numbers.


-- 
Met vriendelijke groeten,   Ernst


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