Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,735   Posts: 1,515,400   Online: 1092
      
Page 1 of 3 123 LastLast
Results 1 to 10 of 28
  1. #1
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,372
    Images
    4

    Split grade printing: the key to success

    There is a new application note on split-grade printing on the Darkroom Automation web site.
    http://www.darkroomautomation.com/su...sgmeasured.pdf

    The article stresses that the key point in getting split grade printing to work is the necessity of treating high contrast prints differently from low contrast prints.

    In this context high contrast prints are those made with a longer #5 exposure, and low contrast prints are those made with a longer #00 exposure.

    When split grade printing in the traditional 2-test strip method:

    • High contrast prints must be made with the black-point/high contrast test strip made first.
    • Low contrast prints must be made with the white-point/low contrast test strip made first.


    The article gives detailed information on split grade printing with a meter. It presents a simplified approach in which a simple graph gives you all the information you need to find the correct filter ratio. The complete contrast response of a VC paper - over all filtration settings - can be found with just three prints of a step wedge.
    Last edited by Nicholas Lindan; 12-31-2008 at 05:06 PM. Click to view previous post history.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  2. #2
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,101
    Looks like a well thought out system.

    I agree with you 100% on the pros/cons of split grade. Especially #1 "Only works with prints with pure whites/highlights and blacks." I recall last year when I was starting split-grade, I saw an exhibit at the Cleveland museum (I believe from their own collection) and I specifically paid attention to blacks and white. Most prints did NOT have full black or white.

  3. #3
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,101
    I was looking at your graphs and my own split grade graphs and realized that using this graph, you can make a SINGLE test print. Assuming you have the Darkroom Automation meter.

    Use the meter to get the density range of the projected image. Use this number to find the corresponding radial line on the graph. The radial lines are lines of equal contrast. Then guess at a time with which to expose color (either color first) and read the corresponding start time for the second color exposure sequence off the graph. (Using a large step wedge overlay over the paper)

    So, for a negative with a density range of 1.2 log, use the 120 ISO R radial line. Do the test strip with High contrast filter starting at, say 20 seconds and the Low contrast exposure sequence starting on 40 seconds.



    Of course this could be easily re-drawn to show "Stops" on the x and y axis. The lines of constant contrast are plotted as ISO(R) from the log density, which could easily be converted to "Stops" of density range. (ISO(R) divided by 30). Though, I see the Darkroom Automation meter will show both stops and density. I see that it is only $94. Its on my 'want list'

  4. #4
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,372
    Images
    4
    Quote Originally Posted by ic-racer View Post
    I was looking at your graphs and my own split grade graphs and realized that using this graph, you can make a SINGLE test print. Assuming you have the Darkroom Automation meter.
    Actually, the purpose of the meter and the application note was to do split grade printing with NO test prints.

    You meter the negative contrast - from the graph this directly gives the ratio of filtered exposures.



    The key point in the system is that low and high contrast prints are treated in different, though symmetric, fashion.

    If the #5 filter exposure predominates (low contrast negative/high contrast print) then expose with the #5 filter for the metered shadow exposure. The #00 filter exposure is less by the filter ratio.

    If the #00 filter exposure predominates (high contrast negative/low contrast print) then expose with the #00 filter for the metered highlight exposure. The #5 filter exposure is less by the filter ratio.

    Thats it. No test prints. One chart. Of course you can do the same thing with the meter and graded filters and save a lot of palaver.

    The downside to split grade is, as you have mentioned, that there is no direct placing of any mid-tones or mid-tone contrast, and mid-tones are really where the image interest lies and printing control should reside.

    The upside to this method of split grade is that charts can be developed for any paper with 3 shots of a step tablet.
    But that upside is only because the system's only information on a paper's response are its black and white points.

    This method reinforces the anecdotal posting on APUG that for printers making the low contrast test strip first for the highlights find that split grade only works well for them when printing contrasty negatives. On can only assume those who find it works, and make the black test strip first, normally have low contrast negatives. Those who find it works either way make normal contrast negatives, and could save themselves a lot of bother by printing with no filtration at all.

    Quote Originally Posted by ic-racer View Post
    So, for a negative with a density range of 1.2 log, use the 120 ISO R radial line. Do the test strip with High contrast filter starting at, say 20 seconds and the Low contrast exposure sequence starting on 40 seconds.
    Hmmm. For under-lens Ilford filters with a PH212 bulb/condenser light source, equal exposures with #00 and #5 filters give a 3.8 stop / 1.14 log / 114 ISO (close enough to 120 for government work) contrast.

    Of course, with a color head, that ratio is going to be different as the full-yellow and full-magenta filter settings are going to have different filter efficiencies from the Ilford filters.

    The 2:1 ratio for soft/hard exposures for normal grade with a color head makes sense if one assumes Ilford added 1 stop of ND to the #5 high contrast filters, which they may have done to keep the printing times for the highest contrast grades at 2x the softer grades. If the same amound of ND was dialed into a color head for the magenta exposure then equal exposures would give a normal density print.
    Last edited by Nicholas Lindan; 01-03-2009 at 11:28 PM. Click to view previous post history.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  5. #5
    Dan Henderson's Avatar
    Join Date
    Feb 2005
    Location
    Blue Ridge, Virginia, USA
    Shooter
    4x5 Format
    Posts
    1,891
    Images
    241
    Nicholas: I am confused over your repeated references to low contrast negative/high contrast print, or vice versa. Is that meant to mean that if one has a negative with a density range that produces a lower contrast print than desired with no filtration, or perhaps equal low/high filtration, one would expose through the high contrast filter first, but with the low contrast filter first if the opposite were true?


    web site: Dan Henderson, Photographer.com

    blog: https://danhendersonphotographer.wordpress.com/

    I am not anti-digital. I am pro-film.

  6. #6
    titrisol's Avatar
    Join Date
    Aug 2004
    Location
    Rotterdam
    Shooter
    Multi Format
    Posts
    1,671
    Images
    8
    Ralph Lambrecht (darkroom magic) had a guide like that to be used with the Ilford EM10 enlarging meter. I found that you simply expose using the #5 filter to make the blacks black, and then with the #0 filter (I have no 0000) for the midtone (by experience)
    Mama took my APX away.....

  7. #7
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,372
    Images
    4
    Quote Originally Posted by titrisol View Post
    I found that you simply expose using the #5 filter to make the blacks black, and then with the #0 filter (I have no 0000) for the midtone (by experience)
    Now, try that with a really contrasty negative and I think you will find it doesn't work as well - and that doing the #0...0 exposure first and then determining the black exposure gives a more controllable result.

    The idea that the printing technique needs to change depending on the printing contrast is briefly mentioned in Beyond Monochrome but then seems to be dropped from the subsequent examples and advanced techniques. The book also does not specify the dividing line. It isn't really a sharp demarcation but a region between -1 and 0 on the graph below. However, an arbitrary point at equal filtration works well enough.



    I think this point is the key to getting split grade to work, and is the reason that many people find 'it works about 1/2 the time'.

    There are many ways to skin a cat and even more ways to make a very good print. Some are better than others for some people. There is no magic path, and the application note certainly isn't pretending to be THE METHOD, it's just one method among many, and one that some printers may find useful and fitting to their temprement.
    Last edited by Nicholas Lindan; 01-04-2009 at 01:09 PM. Click to view previous post history.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  8. #8
    Nicholas Lindan's Avatar
    Join Date
    Sep 2006
    Location
    Cleveland, Ohio USA
    Shooter
    Multi Format
    Posts
    2,372
    Images
    4
    Quote Originally Posted by FirePhoto View Post
    Nicholas: I am confused over your repeated references to low contrast negative/high contrast print, or vice versa.
    Low contrast negative: flat, mushy, grey on grey ...
    So a high contrast print (one made with high contrast filtration or paper grade) and a low contrast negative make a finished photograph with normal contrast.

    You are right, it does seem a bit confusing in retrospect: "high contrast printing technique" might be a better term. "High contrast print" in this context doesn't mean the finished print is high contrast. Of course, you can make a high contrast print from any negative - it's the printing technique that matters, not the negative contrast.

    And vice-versa.

    Thanks for pointing it out.
    Last edited by Nicholas Lindan; 01-04-2009 at 10:24 AM. Click to view previous post history.
    DARKROOM AUTOMATION
    f-Stop Timers - Enlarging Meters
    http://www.darkroomautomation.com/da-main.htm

  9. #9
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,101
    Quote Originally Posted by Nicholas Lindan View Post
    Actually, the purpose of the meter and the application note was to do split grade printing with NO test prints.

    You meter the negative contrast - from the graph this directly gives the ratio of filtered exposures.
    Duh... Now I see!! For some reason I was interpreting the method as placing the large step wedge on the paper when making the exposure...Never mind...

    Hmmm. For under-lens Ilford filters with a PH212 bulb/condenser light source, equal exposures with #00 and #5 filters give a 3.8 stop / 1.14 log / 114 ISO (close enough to 120 for government work) contrast.
    Good pickup on that graph. That graph I posted is actually for a bare W45 Aristo, therefore somewhat distorted, compared to other light sources.

  10. #10

    Join Date
    Jan 2005
    Location
    south central Missouri
    Shooter
    Multi Format
    Posts
    1,926
    Images
    9
    All the graphs and colored lines make me dizzy. Guess that's why I like Fred Picker for film exposure and Les for printing.

    Pretty basic, even if you eat up a couple of sheets of film or paper.

    Mike
    Last edited by mikebarger; 01-04-2009 at 03:23 PM. Click to view previous post history.

Page 1 of 3 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin