Appena torno a casa ti dico, nel mentre ho trovato questa pagina su un forum americano con una breve discussione che allego:https://www.photrio.com/forum/attachmen ... pdf.89634/
"I am in the process of setting my own dark room and, being a 35mmRF and 6x6 shooter, I have decided to purchase a Durst M800 and CLS 80 head. Do any of you use this combination? Recommendation for multi-grade papers for the setting on the head VS filter grades?
Moreover I will highly appreciate any help in finding the manuals for both of the items.
Thanks a lot,
PS In case I fail to find the manuals/data for the head, does anyone knows how to do the calibration of the head for the filter grades? Cheers!"
"Don't know about that specific enlarger but Durst use units of 130 or 170 depending on the model.
The datasheets which are inside each box of paper you buy will tell you what the units to use are for each grade.
My durst modular 70 uses the 170 unit scale and my durst L1200 uses the 130 unit scale.
The units on my Durst L1200 are exactly match what Ilford say I should be using. Well they were for the old MGIV paper. I haven't tested the new Classic version yet.
Other makes of paper aren't so exact. But the thing is that with Y+M filtration you really don't need to think in exact grade terms. You just use what the paper datasheet says to use and adjust to taste as you print. You will soon get a feel for it if you print often enough.
If you want to test then you will need a transmission step wedge. You print that at softest contrast (grade 00) so that you have at least one white step at one end and one black step at the other. i.e. the print fits somewhere within the step range. You then print at all the other grades using same time and without moving/adjusting anything so you get a print for each of grades 00,0,1,2,3,4,5 grades. You then compare the prints by lining them up and if all is well, one of the steps (for example step position 10) will have the same tone on all the prints. If you have a densitometer even better as you can graph the results but it isn't a must to do that.
And use fresh new paper for the test and not some old stuff because old paper loses contrast and won't you show you true capability of the paper."
Darò un occhiata a questo foglio presente nelle carte Ilford, vedremo.