Step Wedge Question

Discussion in 'B&W: Film, Paper, Chemistry' started by photomc, Jan 31, 2005.

  1. photomc

    photomc Member

    Messages:
    3,575
    Joined:
    Jul 20, 2003
    Location:
    Texas
    Shooter:
    Multi Format
    Did some paper test yesterday using the Stouffer 21 step Wedge that came last week (it was to overcast and wet for film testing, and I had to find some reason to go into the darkroom).

    Anyway, I noticed that step 11 on the low side is not the same as step 11 on the high side. Can anyone else look at the one they have (this is the 4x5) and confirm? Is this normal and if so what is the reasoning behind it?

    I actually learned quite a bit about the papers I use and will post the finding this evening when I get home from work. And maybe some of you will be able to assist me in understanding what I found.

    Thanks as always....

    BTW where I stated low side vs high side was describing (1-11 low vs 11-21 high in case there were any question as to what this nut is talking about :D )
     
    Last edited by a moderator: Jan 31, 2005
  2. Peter Schrager

    Peter Schrager Subscriber

    Messages:
    2,069
    Joined:
    Jul 19, 2004
    Location:
    fairfield co
    Shooter:
    Large Format
    Step Wedge

    Photomc- Howard Bond has done some really excellant articles in Photo-Techniques mag. with step wedges. I'm pretty sure that they have them in one of the special reprints they sell. Yes ,you can do some testing and save alot of time for the changes between filters but I only got about 2/3 of the way with it. At least you'll have a good basic understanding of what the paper can do or not do.
    Regards Peter
     
  3. Jorge

    Jorge Inactive

    Messages:
    4,532
    Joined:
    Sep 6, 2002
    Shooter:
    Large Format
    This is normal with the 4x5 projection step wedge Mike. Mine is the same way. Usually the difference is about 0.03 to 0.04. Just use the side that gives you a smoother curve. If you want true even steps values you need to purchase the Transmission scales, but they dont come in 4x5 and are more expensive. For what you are doing the one you have is fine.
     
  4. gainer

    gainer Subscriber

    Messages:
    3,725
    Joined:
    Sep 20, 2002
    If you had paid the money for a calibrated step wedge you would have gotten a list of the densities. It would probably show the difference. I have noticed the same thing with the TP 35-- that the two labelled "11" are not the same.
    A calibrated wedge, at least the ones I have got from Stouffer, is not a precision wedge, but one that has been measured and the steps listed by measured density. The uncalibrated wedge is adequate for much work. If you have an accurate densitometer you can calibrate it yourself.
     
  5. noseoil

    noseoil Member

    Messages:
    2,898
    Joined:
    Oct 6, 2003
    Location:
    Tucson
    Shooter:
    Multi Format
    One thing I've noticed about using a step wedge is that the neighboring density affects how the eye sees a value. A dark value next to a light value makes the light value appear lighter. Try covering up one side or another and you will see what I mean. It's just an optical delusion. tim
     
  6. photomc

    photomc Member

    Messages:
    3,575
    Joined:
    Jul 20, 2003
    Location:
    Texas
    Shooter:
    Multi Format
    Good information guys..lunch break. Since I do not have a densitometer (yet, sounds like one may be in my future) I will relate a little of what I observed with the paper test. First thing I noticed is that Ilford MG IV had much more range, seems like it started at step 4 and went to step 17 (both were barely identifiable), next paper was Agfa MC111 which did not have as much range as the Ilford steps 5-14, then Forte which was even less 5-13.

    Now for some reason, I was surprised by these findings each one was exposed with a Nikon 150, on a Bes. 45 with a dichro head - lens was wide open, done using 5 and 6 sec exposure, developed in Zone VI dil. 1+3 for 2 minutes, water stop, then Ilford rapid fix for 4 min. and washed for a couple of hours. The inital impression of each one - WET, was not the same as the dried down (not trying to start a debate about dry down - just noticed the difference).

    Still have some Berger and Oriental to test, but so far it has been a good exercise and very revealing. Thanks to each of you for your input, which as always is very helpful.
     
  7. noseoil

    noseoil Member

    Messages:
    2,898
    Joined:
    Oct 6, 2003
    Location:
    Tucson
    Shooter:
    Multi Format
    Mike, try marking a test shot when it is wet and you will be able to track dry-down pretty well. Neat stuff, isn't it? Alt process will be even more interesting. Sounds like things are going well for your tests. tim
     
  8. Dave Wooten

    Dave Wooten Subscriber

    Messages:
    2,720
    Joined:
    Nov 1, 2004
    Location:
    Vegas/myster
    Shooter:
    ULarge Format
    "neighboring density value" yes...Minor White used to talk about "convincing Black" not always a good idea to display certain platinums next to certain silver prints......each print stands on its own values.
     
  9. photomc

    photomc Member

    Messages:
    3,575
    Joined:
    Jul 20, 2003
    Location:
    Texas
    Shooter:
    Multi Format
    Resluts of Step Wedge Testing

    OK, here are the results of the testing from yesterday. I used a Stouffer RZ9 Zone System Chart as a visual (subjective) reference. So what conclusion have I made from the information you might ask? Not sure yet, but first impression is that Ilford MG IV has much more range, and more tones in between (1/2 stop) stops in the higher (lighter) values than does Agfa and Forte, Agfa being a close second and Forte was a step per zone (1/2 stop) for Zones I-VIII.

    Also, noted from the 6 second exposure that the Forte paper seems like the shadows (zones II - IV) would block up very quickly, leaving me to think that if exposure is not dead on this paper could be harder to print on than say Ilford or Agfa.

    So here are the results, don't really mean much except to me, but thought I would share what I found and would be interested in hearing what others have found. Do these results sound reasonable to you? Or have I missed the boat and need to go back and do more test?

    BTW, did do some testing with Ziatypes on Saturday, but after 30 min. and only steps 1 - 4 showing up, decided that after almost 2 years that Sol. 1 (Ammonium Ferric Oxalate) may have given up - the bottle has may 2 ml left in it. So will have to wait until I get some fresh AFO and Pd in to test them.


    Agfa MC111 Zone I - step 4
    Zone II - step 5
    Zone III - step 6
    Zone IV - step 7
    Zone V - step 8
    Zone VI - step 10 and 11 (high side)
    Zone VII - step 13
    Zone VIII - step 14
    Zone IX - step 17

    Forte VC Zone I - step 4
    Zone II - step 5
    Zone III - step 6
    Zone IV - step 7
    Zone V - step 8
    Zone VI - step 9
    Zone VII - step 10 and 11 (high side)
    Zone VIII - step 12
    Zone IX - step 14

    Ilford MGIV Zone I - step 5
    Zone II - step 6
    Zone III - step 7
    Zone IV - step 8
    Zone V - step 10
    Zone VI - step 11 (low side)
    Zone VII - step 14
    Zone VIII - step 16
    Zone IX - step 18
     
  10. chrisg

    chrisg Member

    Messages:
    22
    Joined:
    Jan 5, 2004
    OK, wedge density changes by 0.15 OD units per step on a 21 step wedge, so you've got a density range (Zone I to Zone VIII) of 1.5 for the Agfa, 1.2 for the Forte, and 1.65 for the MGIV. That seems pretty long. (Or I made mistake on my calculation.) I would have expected a density range of about 1.0 for MGIV with unfiltered light. What filter/dichroic setting were you using for your exposures?
     
  11. gainer

    gainer Subscriber

    Messages:
    3,725
    Joined:
    Sep 20, 2002
    I think the density range of a negative is usually figured from significant shadow to significant highlight, which would be from Zone III to Zone VIII. Count the intervals between Zones, which means leave out the first one.
     
  12. photomc

    photomc Member

    Messages:
    3,575
    Joined:
    Jul 20, 2003
    Location:
    Texas
    Shooter:
    Multi Format
    Chris, the prints were made on a Beseler MX with a dichro head and filters set to 0 (ie no filter).

    Thanks for the input - I thought the density range looked a bit long..

    Do remember that the readings are not from a densitometer, but a subjective readings by comparison to a visual zone chart (Stouffer RZ9)..so this is much less scientific - though even subjective, I think it should be within a 1/2 step.
     
  13. ChuckP

    ChuckP Subscriber

    Messages:
    646
    Joined:
    Jan 8, 2003
    Location:
    NW Chicagola
    Shooter:
    Multi Format
    I'm a little unclear on what you're testing. Can't you use filters to basically get the same contrast range out of each of these papers? I suppose you can test using the extreme filters to see which paper has the best contrast range. And check the paper curves of papers that are matched in overall contrast. Or figure out paper response to different filters and your enlarger light.
    Chuck
     
  14. chrisg

    chrisg Member

    Messages:
    22
    Joined:
    Jan 5, 2004
    Printing without a filter is usually similar to a Grade 2 or Grade 2.5, so I'm going to stick my 'DR=1.0 is normal' statement. You were seeing an 8-11 step range as opposed to 7, so even if you figure plus or minus 1/2 a step uncertainty in your estimate, your observed range seems high.

    Did you keep track of developer temperature? Depending upon what you were using, if it was running warm (say 75?) that could stretch your range some - maybe a full step. I'll pull out some old test strips and see what my ranges were. I think I was typically 6-7 steps for Grade 2-3 filters and MGIV. Seagull had a touch longer range than MGIV. Bergger NB was very similar to MGIV. Developer didn't seem to matter much, although the changes in temp would expand/contract ranges a bit.

    Chris
     
  15. photomc

    photomc Member

    Messages:
    3,575
    Joined:
    Jul 20, 2003
    Location:
    Texas
    Shooter:
    Multi Format
    First, should explain that what I was really doing was using the step wedge as a 'perfect' negative, if you will. One with a full range of tones/zones. My intent was to see how each paper would respond...which I think I found out. Temp was a nice 68 F (which this time of year is pretty normal around hear, now summer is way different). I will attached a scan of each test, though my scanning skills are so so.

    The one thing I found with the test is that Ilfrod seems to handle more subtle high tones between zones VI and IX, so if they are in the negative they would print. The other thing is to lean what a given zone on a print would look like in the negative state, not something that I always could see when looking at a book.

    Thanks for all the comments, and feel free to share more thoughts.

    BTW the scans do not show as much of the subtle tones as the origianls do.
     

    Attached Files:

  16. dancqu

    dancqu Member

    Messages:
    3,676
    Joined:
    Sep 7, 2002
    Location:
    Willamette V
    Shooter:
    Medium Format
    "neighboring density value" I ran into that with my step wedge
    and some informed fellow at rec.photo.darkroom mentioned just
    that as the cause; a little tricking of the eyes.

    Of course I had to confirm, so off to my Tobias TB+ to measure
    the two densities. Both elevens the same. Dan