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  1. #11

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    Does anyone have an alignment for dummies link or reference, because I'm not following any of this...

  2. #12
    blansky's Avatar
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    Usually every enlarger needs alignment. The manual describes how to do it. One needs to align the negative carrier support as well as the enlarger head in relationship to the baseboard.

    If you use an f stop somewhere in the middle (f8, f11) you may never have a problem but if you enlarge wider open, then the depth of field won't cover your butt.

    The tools that we are talking about is a Versalab Laser Alignment tool which shoots a laser light up off a mirror type surface on the lens or negative holder and bounces the light back down to the baseboard. By making adjustments you align everything.

    Many people here have made home made devices for very little money that work great. Check the archives here or photonet and you'll find tons of info.


    Michael
    I couldn't think of anything witty to say so I left this blank.

  3. #13
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    Hi Michael

    It is my understanding that closing down a process lens for enlarging does not produce any ""Depth of Field" issues.
    Enlarging process lenses are made to be flat field and you may only see a slight depth of focus.
    Closing down the lens should not give you better sharpness .
    Apo lenses are made to work wide open or closed down with the sweet spot two stops from wide open on any lens. they are dramatically different than camera lenses.
    I think this needs clarification as taking the logic that depth of field will pull a negative into focus , workers would start using f32 f22 .
    Could someone help me on this issue as I have heard this before on previous threads and to my knowlege this is not the case.

  4. #14

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    Shorter process lenses [up to 600mm?] are designed to be used at F/22. Longer ones at F/32. The real short ones [105mm?] might be designed for use at F/16. The lenses are at thier best at the designed F/stop.

    Isn't it two issues? Depth of field and depth of focus. The negative is on one side of the lens the paper the other.

  5. #15
    Ed Sukach's Avatar
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    Lenses are lenses. Depth of Field/Focus is not directly related to "Flatness of Field".
    Using a smaller f/stop *will* increase Depth of Field/ Focus.
    Try tilting the easel in enlarging to correct perspective. Stopping down is virtually necessary.
    "Apo" is a shortening of "Apochromatic" ... supposedly additional care is taken to reduce chromatic abberation - a.k.a. "color fringing"" - But I don't know --- Certainly some of the non-Apos are very good as well. Possibly, "APO=Higher Price".

    Yeh, yeh... "Best" aperture is usually designed to be in the center of the aperture range .... but that is probably as over-critical as you can get. I haven't yet seen an enlarging lens that was materially - or even noticeably worse at the extremes of the range.
    If they were as "bad" as some believe, they would not be fitted with adjustable f/stops.
    Carpe erratum!!

    Ed Sukach, FFP.

  6. #16
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    Hi Ed

    I think I must disagree,
    I am sure that the design of lenses for enlargers are not built with depth of field in mind. The are designed to be focused sharp along a flat field which is the enlarger easal.
    I have never corrected un - sharp edges of a print by closing down, alignment of the lensboard negative stage and easal is the only way that I am aware of getting sharp edge to edge.
    As well try putting a lith negative of very small sharp type into your enlarger and project , and then start wide open , middle f stop, and very closed down.
    adjust the density so that each print equal.
    You * will * find that some of the prints are much sharper and ledgible to read.
    In my past , I did a lot of multiple exposing of images and type onto photographic paper and film and I know that selection of apeture for the type was critical.
    This may be a simple test to do and I think that it does indicate some fstops on an *enlarging lens * are better than others.
    This simple test can also answer the debate whether you should have white walls or black walls surrounding ones enlarger.
    Granted when we did these test we were making 8ft murals and the room we worked in was large. We found the type to be sharper with black on the walls not white.

  7. #17
    blansky's Avatar
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    I'm not all that technical. My experience of depth of field/focus is really just anecdotal and I find that printing wide open is not optimal but in my case necessary, for now.

    In my work optimal sharpness is not as necessary as someone doing scenics for example. I try for very sharp eyes (portraits) and the rest is not a huge concern, especially falloff etc.

    Michael
    I couldn't think of anything witty to say so I left this blank.

  8. #18
    Ed Sukach's Avatar
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    I'll try to answer, item by item. Hopefully I'll get the format right..

    Quote Originally Posted by Bob Carnie

    I am sure that the design of lenses for enlargers are not built with depth of field in mind. The are designed to be focused sharp along a flat field which is the enlarger easal.
    The idea of a "flat field" is a primary concern. Even though there are "primary design criteria", there are also "secondaries" ... and those characteristics that are inherently "there". Every "flat field" lens will have a finite depth of field or depth of focus. Example: Mount an enlarging lens onto the lensboard and use it as a taking lens. You will see that everything focuses in much the same way as a taking lens - there will be no razor thin "plane" where everything "snaps in" and then "snaps out".

    I have never corrected un - sharp edges of a print by closing down, alignment of the lensboard negative stage and easal is the only way that I am aware of getting sharp edge to edge.
    ??? Depends on WHY the edges are "unsharp." If sharpness isn't there in the negative, there is little hope for improvement. If there is an amount of misalignment - Stopping down most certainly will increase apparent sharpness. Try tilting the easel -- something I've done to correct perspective. One focuses near the center, and then stops down to gain a suitable amount of "sharp".

    As well try putting a lith negative of very small sharp type into your enlarger and project , and then start wide open , middle f stop, and very closed down.
    adjust the density so that each print equal.
    You * will * find that some of the prints are much sharper and ledgible to read.
    True ... there is an "optimum" aperture for all photographic lenses - part of the design criteria. Has little to do with alignment, though.
    I will, though, take exception to your use of the word "much". With my lenses, Rodenstock, Schneider, Omega, Elgeet(!) - what the heck is on that old Federal ? - It cannot be described as "much". At least not much-- and I have done a fair amount of lens testing (Optical Quality Assurance Specialist - in a previous life) in my opinion.

    Come to think of the "Elgeet" lens -- that is on an old DeJur enlarger I got as a gift. It needs to be rewired ... the electric cord accompanying it disintegrated with time. It has a tilting negative carrier, used for perspective control, and a much neater way to do it than film cans, bricks, sundry other items under the easel to obtain the necessary amount of tilt.

    I guess one could characterize the use of that carrier as, "Aesthetically Adjustable Misalignment".
    Carpe erratum!!

    Ed Sukach, FFP.

  9. #19
    Ole
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    During a long printing session I first checked the focus over the entire printing area.

    I then printed the first (5x7") negative using a glass carrier, put a second (13x18cm) negative in a glassless carrier, printed that, next a 4x5" negative in another glassless carrier, and finished with a 9x12cm negative in a second glass carrier.

    Never once did I adjust focus or realign the enlarger, I merely swapped paper sizes. All prints were sharp from corner to corner.

    BTW, I used the same 180mm Rodagon lens too. And the enlarger is a Durst L138S.
    -- Ole Tjugen, Luddite Elitist
    Norway

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