Negative vs Positives

[gtmo]

Can someone shed some light into the following.

We still make film and always calibrate using negatives, we tried to calibrate with a postivie and there is quite a difference between the measurement of the Negs and Positive.

Is there a logical reason why this is?

Example: Neg 50% at 53 Positive 50% at 58 Neg 60% at 62 Positive 60% at 67


Using Harlequinn Rip.


Thank you in advance for any info.

 

[SteveSuffRIT]

Just so I better understand, you are using the same film but the imagesetter exposing polarity is being changed?
If you corrected the calibration on negative film 50=50, then output positive does it get better?
Steve Suffoletto

 

[gtmo]

Hello Steve,


Thanks for asking. Have not gotten it to a 50=50 we usually just go with a 50% + or - 2%.

 

[Slammer]

Oh! I had that too, yonks ago. The cause was that the calibrations Strip was set with a round dot screen, better would be a euclidian as it should have a perfect checker-board at 50% if your callibration is correct.