relating paper grade to number of stops

[BetterSense]

If I contact print my step wedge, I get a certain number of stops between just-barely-darker-than-white and just-barely-lighter-than-black. Is there a way to relate this "tonal scale" to paper grades so that e.g. I could tell the paper grade of unknown paper?

 

[Xmas]

Yes do a test strip of step wedge on unknown graded paper.

Do a set of similar step wedge strips at half paper grades with a VC paper.

Pick nearest half grade.

Good negs easy to print bad negs difficult.

 

[BetterSense]

I could use my Ilford multigrade filters and plot a curve. However, I would rather not use my current multigrade filters as a standard. I don't know how accurate they are since they are a few years old.

How are paper grades defined? I had a hard time finding anythnig via google.

It would be nice if we just used straight-line contrast to express, um, contrast instead of inventing another arbitrary scale in the form of paper "grades"

 

[payral]

The answer there.
http://www.jbhphoto.com/articles/vcno2/eyeballcal.pdf

 

[BetterSense]

Perfect; that's exactly what I was looking for. I will also use this to calbrate my colorhead for VC printing.

In case the link breaks in the future here is the meat and potatoes:


Log(density range), Paper Range (stops),GRADE
0.43 1.43 6
0.58 1.93 5
0.73 2.43 4
0.88 2.93 3
1.05 3.5 2
1.28 4.27 1
1.55 5.17 0

 

[Jim Noel]

That is for one paper made by one manufacturer. It may be close, but is unlikely to be true for any other paper. Picker's work is so old seriously doubt that the paper he tested is even made today. IIRC the paper he sold was made by a manufacturer in France.
If your step wedge has 21 steps each step is 1/2 a zone, or 0.15 units of density. When you print it on your paper of choice you will most likely find that it reproduces as such on a narrow band of 4 or 5 stops at the most. You need to find where those steps are, and print to get your image on that straight line portion of the curve. if using VC paper, each filter will produce a different result. The higher the number of the filter, the more narrow the straight line.

 

[Oren Grad]

How are paper grades defined? I had a hard time finding anythnig via google.

According to this standard:

http://www.iso.org/iso/catalogue_detail.htm?csnumber=13355

Ilford cites the "ISO range" numbers for each paper (or each paper and each VC filter) in the data sheet for that paper. The grade numbers attached to papers, or to VC filters, are more or less arbitrary, but the ISO range numbers give you some sense of how different papers compare to each other at a given arbitrarily specified grade number.

 

[ic-racer]

Some potentially useful info here: (there was a url link here which no longer exists)

 

[BetterSense]

From the link provided above:

Typical figures might be
Grade 5 = ISO(R) 40 to 45;
Grade 4 = ISO(R) 60 to 70;
Grade 3 = ISO(R) 80 to 90;
Grade 2 = ISO(R) 100 to 110;
Grade 1 = ISO(R) 120 to 130;
Grade 0 = ISO(R) 140 to 150;
Grade 00 = ISO(R) 160 to 180.

This is in fair agreement with my table above distilled from the earlier pdf.

This is from the Ilford MGIV RC datasheet:
Filter 00 0 1 2 3 4 5
Range (R) 180 160 130 110 90 60 40

 

[RalphLambrecht]

You can conduct a paper test. see attached, but you'll need a densitometer.

 

[DREW WILEY]

Are you trying to do things the hard way? A step wedge behave differently than a negative than an actual subject. And paper grades are chosen not just to span the hypothetical illuminance range of something, but to creatively interpret a negative. And different combinations of film, developer, and paper all have their own set of variables. If you are doing research in sensitometry, that is one thing - and you'll need a fair amount of training and specialized equipment. If you trying to get good prints of real-world subjects, that is something else entirely, and you need to approach the problem on that basis. Shoot and print and experiment and ask questions as you go. I have certainly spent more than my fair share of time plotting curves with a densitometer. But when it comes to paper grades and VC papers, tinkering with simple test strips and actual subject shots gets me from point A to point B a thousand times faster.

 

[RalphLambrecht]

Pleae note that the actual standard does not refer to grade numbers,just exposure ranges.grades are a paper manufacturer conventionnot an ISO standard.In the standard, grade numbers were only briefly mentioned in the appendix.You are better of communicating LER.along the same lines,filter numbers have little to do with paper grades