Split grade and unsharp?

Discussion in 'Enlarging' started by Thomas Bertilsson, Aug 11, 2009.

  1. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    Today I'm printing some seascapes with large expansive skies. I'm enjoying it immensely.

    I use variable contrast paper, Ilford Multigrade filters under the enlarging lens, condenser enlarger.

    So I ran into a problem. I have made two prints of the same negative so far, and after about 1.5 hours of printing I had the print where I wanted it.
    The whole print made at Grade 2 with a 40s main exposure, dodge the bottom and center for 15s, burn bottom for 15s (basically dodging the center for 15s), burn right side for 8s, burn top right corner 20s, burn top left corner 12s, and burn entire top of the print for 15s.
    So I processed this print, and although I was happy with it, it wasn't perfect. I decided I wanted to give a zap at the end with the Grade 5 filter for 10s, and I did. But this print is unsharp while the other is tack sharp.

    Process: I use a metronome and count seconds. I use a big card to do all the dodging and burning and after the Grade 2 exposure is completed, I cover the whole print, then gently slide the Grade 2 filter off the holder under the lens and replace it with the Grade 5 filter. I didn't even touch the enlarger itself and the 3x3" filters weigh maybe two grams each, i.e. not enough to actually move the enlarger.
    Then uncover the print again, and turn enlarger off after the Grade 5 zap was completed.

    So I tried it again, and again, and again. No matter how gently I try to swap the G2 filter for the G5 I get the same amount of blur in the image that I just cannot explain.
    What's going on here?

    Tonally the print is all I want it to be, but I cannot for the life of me get rid of this unsharp element.

    Thanks,

    - Thomas
     
  2. Lee L

    Lee L Member

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    Which enlarger?

    Could it be heat build up, or cooling of the negative while changing filters? That could be popping or unpopping the negative.

    Try the sequence without printing while watching with a grain magnifier to see if you can find the point at which things go out of focus.

    Lee

    P.S. I'm not gonna tell you to print with a single filter like a 'real' photographer. Someone else will be along to do that momentarily, likely by the time I've finished this sentence. :smile:
     
  3. brofkand

    brofkand Member

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    The 5 filter may be scratched, smudged, or otherwise damaged. Especially if the filter is UNDER the lens, in the light path, that could be the problem. Those kind of filters always make me nervous. Does your enlarger have conventions for filters INSIDE the enlarger itself? If so, I'd do that while making darn sure the enlarger's adjustments are tightened as much as they'll go.

    When you cover your paper, you may be moving it the slightest amount. I don't fully understand why you're covering the print.

    Since the blur is consistent, I'd say you're either moving the paper or the filter is damaged.
     
  4. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    False alarm...

    I had to go from an aperture of f/8 to f/5.6 on the lens. That's enough to introduce un-sharpness... I did the same print at f/8 and things are fine again. Damned enlarger lens, it's supposed to be a good one, a Rodenstock Rodagon. The sharpness at f/5.6 compared to f/8, in a print as small as 10x10" is very poor. Clearly visible to the human eye.

    By the way, about covering the print - remember I use a metronome. I turn the enlarger on at the beginning qof the sequence and turn it off at the end. There is, to me, no sense in turning it off in the middle of doing things. I cover the print so I can better see when I change filters.
    I've never seen the filters introduce any problems under the lens, even if they're not perfect. Not enough to notice anyway. The difference in sharpness I'm talking about is not subtle.q
    Covering the print is also a very useful tool that I've used in the past when I use diffusion material above the print, or when I swap dodging tools.

    Lee - You are probably right. I normally don't use split grade printing, but with this particular print I needed some extra pop to the sky, and going from Grade 2 to Grade 2.5 or 3 meant that I had to re-think the entire image.

    - Thomas
     
  5. Lee L

    Lee L Member

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    Glad you got it sorted Thomas. I do split grade print myself sometimes, so I wasn't really telling you not to. I was just predicting the standard, extremely thorough variety of answers.

    Lee
     
  6. Dan Henderson

    Dan Henderson Member

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    Thomas: don't be too hard on your lenses. Just like camera lenses, enlarger lenses are usually sharpest 2-3 stops down from wide open. I made some test prints of a highly detailed subject at different apertures a few years ago and I was astounded at how much the sharpness dropped off at wide open or fully closed.
     
  7. dancqu

    dancqu Member

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    Just wondering, do you focus with lens wide open?
    If so is there any shift in best focus after closing
    down one stop? That is do you tweak the focus
    after stopping down? Dan
     
  8. Sirius Glass

    Sirius Glass Subscriber

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    I focus with the lens wide open using a grain focuser, then I stop down, usually to f/8.

    Steve
     
  9. Bob Carnie

    Bob Carnie Subscriber

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    just an observation

    If you are not using glass carrier then I would put the blame specifically on this. The grade 5 being the last blast along with the fact that 5 sets a lot of the detail in the image , maybe the neg is popping during the second blast.
    If you are using glass then this is ruled out.
    I focus wide open and close down, tried it both ways and have never seen any difference in focus of prints.
     
  10. Thomas Bertilsson

    Thomas Bertilsson Subscriber

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    I haven't had much time for internet activities lately... I am printing up portfolios, and am very busy with it.

    The neg carrier I have is not glass. Although I do have some that are, and it has occurred to me that it might be beneficial to use them. I hate spotting prints, though...

    I'll try glass and see if I can increase sharpness. But I did solve my own problem above by stopping down, although admittedly I may be just curing the symptoms.

    Thanks,

    - Thomas
     
  11. clayne

    clayne Member

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    This sounds very suspect to me. Unsharp across the entire print @ f/5.6?

    There is no way the difference between 1-stop should be clearly visible to the human eye with a Rodagon, especially at 10x10" so I believe something else is amiss.
     
  12. dancqu

    dancqu Member

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    I wouldn't be so sure of that. A stop down with my
    F/5.6 El Nikkor is easily seen as sharper. Dan
     
  13. ath

    ath Member

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    Aligning the enlarger properly and using a glass carrier gave a major rise in technical quality of my prints.
    Suddenly all, even the "grainless" films printed with grain...
     
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  15. keithwms

    keithwms Member

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    I would suggest to inkjet yourself a test grid onto transparency stock and put it in the enlarger to check the alignment, with the lens wide open. You can of course also check the registry with a grain finder but it is much more difficult and better for fine tuning.

    I also doubt that there will be significant differences between 5.6 and 8 except maybe in the extreme corners. But bear in mind that I don't enlarge much, the largest prints I make, even from 4x5, are typically 11x14 or smaller. If you are enlarging significantly beyond that then you may indeed need to stop down to f/11 or whatever. Anyway, as I am sure you are well aware, there is almost no meaningful penalty in resolution when stopping down to f/11 - f/22, and there may in fact be significant gains in corner res and overall smoothness of the illumination, so... it's your call. Nevertheless a registry check may be in order. (Now why do I have a strong feeling that somebody is going to lecture me on diffraction limited lp/mm through a stopped down enlarger lens...)

    Actually I never use a glass carrier. I never came to terms with the idea of something touching my negs :wink:
     
  16. Bob Carnie

    Bob Carnie Subscriber

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    I have been using every size of enlarger lenses, rodenstock mainly.
    With a glass carrier, properly aligned, there is no shift in focus if you focus grain wide open then close down two stops.
    If someone here can prove that a shift is happening then I say their lens is crap and align their enlarger and use glass.
    After a few hundred thousand focuses over the last thirty five years I have never once seen this shift when aligned and using glass.
    Ok maybe I bumped into the enlarger once or twice, maybe I swatted the head while changing filters, maybe I hit the easel or kicked the feet, maybe a train went by and bumped the room I was working in.
    But we are talking about good lens , glass and aligned , focus shift is not going to happen.
     
  17. ic-racer

    ic-racer Member

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    Every lens MTF or resolution test for enlarger lenses I can recall ever seeing shows more sharpness at the center at f5.6 vs f8.
     
  18. keithwms

    keithwms Member

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    Yes but that's only part of the story. We just had a very annoying thread on this very topic. Bottom line (for me at least) is that it's not only about center sharpness. Please visit this flashlet and play with the aperture dial. You will see evidence for what you describe as well as some other very important things going on off center.

    While this particular demo is not for an enlarger lens, the behavior is quite typical and evidenced in almost any chart on any lens.
     
  19. Bob Carnie

    Bob Carnie Subscriber

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    I have sold to discerning photographer thousands of prints, to my eye and theirs the prints are sharp.
    Thomas is posting on a problem that I think is caused by not using a glass carrier. Second exposure or during the first I suspect the neg is popping.

    Every technician I have ever worked with focus lens wide open and decide on whether to stop down or not, I stop down two stops from wide open using apo glass,and have never seen a difference.

    Maybe I am missing something here, and have been doing it all wrong all these years... I hope my clients don't find this out.
     
  20. BetterSense

    BetterSense Member

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    I often print at f/22 if it results in reasonable print times. I haven't noticed it unsharpening my prints. Perhaps I should do more testing.
     
  21. cblkdog

    cblkdog Subscriber

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    I've always refocused at the aperture I'm going to print at. It can make a difference. After printing all day I find spotting relaxing so you can send me your prints to spot.
     
  22. dancqu

    dancqu Member

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    Smaller apertures work to correct lens aberrations.
    Some that may be affected include Astigmatism,
    coma, spherical, chromatic, and a few others;
    depending upon the lens.

    Likely diffraction limiting takes a visable toll only at
    very small apertures; perhaps beyond f45. A mute
    point when enlarging due to prolonged exposures.
    Also, diffraction is a function of the absolute size
    of the aperture. For example, two lenses at the
    same aperture will exhibit diffraction in
    proportion to their focal length. Dan
     
  23. Guillaume Zuili

    Guillaume Zuili Subscriber

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    Let me tell you something about Bob...
    This gentleman has a nasty habit to cut my 35mm strip into single frame to put it into his glass carrier...
    I hate that.
    But... Bob made 30x40 prints which were tack sharp.
    I had this issue before. Very frustrating after a long lith dev to see the final image with one corner out of focus.
    Now I only use glass.
    You should do so Thomas.
    If you go close to Bob one day just look for his scissors and hide them !
    Just to piss him off.
    Otherwise you can trust him 100%.
    :smile:
     
  24. dancqu

    dancqu Member

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    Correction

    The last sentence should read: ... will exhibit
    diffraction inversely in proportion to their focal
    length. Dan
     
  25. smieglitz

    smieglitz Subscriber

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    Well. I'm glad this thread just turned out to be something simple about lenses and negative carriers. When I read the title, I thought Thomas was off again combining split-grade filter printing with unsharp masking on lith prints on Solstice dates or some such thing.
     
  26. Guillaume Zuili

    Guillaume Zuili Subscriber

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