MarkL
Allowing Ads
I want to measure the maximum (and minimum) contrast that my collection of well-used second hand light heads are yielding, so that I understand how hard my split filter printing light is, and whether the light sources can reasonably give me all grades. My previous tests with a contact printed 21 step wedge showed that none of the heads could get above grade 3 or so, given my eye-balling of the printed step wedges visually. However, I just received a calibrated 31 step Stouffer transmission wedge and read Steve Anchell’s chapter in The Variable Contrast Printing Manual on calibrating VC papers and would like to do proper evaluation/testing of my heads. A few are additive, one is subtractive, and my Aristo V54Hi and condenser use under the lens filters.
I don’t have a densitometer and currently the used ones on Ebay are really beat up. I wish I had a densitometer so I could read the paper’s IDmin and add the .04, then read IDmax and take 90% of that (I think I have that right). Then I could compare to actual standard grade ranges. Technical testing doesn’t really suit me and seems like overkill for practical printing, but visually looking at a step wedge seems pretty inaccurate. I mean I can count the steps between pure white and pure black, but I should be counting the dark one that is 90% of black right? I can pick the first one below max black, but if I put the print on a light table and look with a loupe, there’s always an extra dark step in there. Same for the white end...usually an extra very light strip. So which dark strip is the one that is close to 90% of max black as far as a densitometer is concerned? Does it matter? Well, when one step makes the difference between the range for a 4 grade versus a 5 grade, maybe it does kind of matter when evaluating the heads?!! Anyone have a good densitometer they want to sell?!
If I find that any of my heads are low in maximum contrast, I hope to be able to bump them up simply by adding magenta or blue Rosco gels above the negative. I would hope to leave any adjusting gels in place for all filter settings and end up with a good grade 0 to 5 range. I know there are lots of threads on the subject of testing paper grades and I’ve read them, but this one is more about evaluating a step wedge by eye (or with a loupe on a light table) vs. this 90% of practical density being used for comparing to ISO paper grades.
Ughhh, no wonder I put this testing off for so long!
I don’t have a densitometer and currently the used ones on Ebay are really beat up. I wish I had a densitometer so I could read the paper’s IDmin and add the .04, then read IDmax and take 90% of that (I think I have that right). Then I could compare to actual standard grade ranges. Technical testing doesn’t really suit me and seems like overkill for practical printing, but visually looking at a step wedge seems pretty inaccurate. I mean I can count the steps between pure white and pure black, but I should be counting the dark one that is 90% of black right? I can pick the first one below max black, but if I put the print on a light table and look with a loupe, there’s always an extra dark step in there. Same for the white end...usually an extra very light strip. So which dark strip is the one that is close to 90% of max black as far as a densitometer is concerned? Does it matter? Well, when one step makes the difference between the range for a 4 grade versus a 5 grade, maybe it does kind of matter when evaluating the heads?!! Anyone have a good densitometer they want to sell?!
If I find that any of my heads are low in maximum contrast, I hope to be able to bump them up simply by adding magenta or blue Rosco gels above the negative. I would hope to leave any adjusting gels in place for all filter settings and end up with a good grade 0 to 5 range. I know there are lots of threads on the subject of testing paper grades and I’ve read them, but this one is more about evaluating a step wedge by eye (or with a loupe on a light table) vs. this 90% of practical density being used for comparing to ISO paper grades.
Ughhh, no wonder I put this testing off for so long!
