Relative ISO Range Numbers for MGIV FB

Discussion in 'Enlarging' started by CPorter, May 5, 2012.

  1. CPorter

    CPorter Member

    Feb 2, 2004
    West KY
    4x5 Format
    With my recent order of supplies I purchased some Ilford MGIV FB paper and I finally got around to determining the relative ISO Range Numbers through the process described in Anchell's Variable Contrast Printing Manual. I thought I would share the results. The range numbers were determined while using the combination: LPL 4550 XLG VCCE (diffused quartz-halogen light source). A Stouffer 21-step tablet was projected onto an 8x10 sheet for each filter setting; the sheets were then developed in Dektol (1:3) for 3 minutes, results not read until toned in selenium (1:10), sheets dried in a microwave. I used 9 sheets, 2 for nailing the proper exposure time.

    The attacment shows a contrast equivalent chart that I scanned from the text, with each of my filtration settings shown in "red", then inserted in the chart in line with the RN result for that filter and the associated contrast grade numbers; a sheet was also used for a "No Filter" exposure. Besides knowing what RN is produced with each of my filtration settings, the other most important information is the spacing between each filter. Sometimes two adjacent filtration settings can produce identical RNs, therefore it would be a waste of time and paper switching to the next setting if it did not increase the desired contrast.

    Attached Files:

    Last edited by a moderator: May 5, 2012
  2. ic-racer

    ic-racer Member

    Feb 25, 2007
    Midwest USA
    Multi Format
    Nice. Thanks for sharing.