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  1. #21
    Bob Carnie's Avatar
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    Absolutely not

    Enlarger Process Lenses do not behave like camera taking lenses
    and have very , very , very limited depth of focus at the paper plane.

    I would hope that none of the experts here would suggest this is an option.

    Quote Originally Posted by kuad View Post
    so using like an f8 would remedy any possible mis-alignment?

  2. #22
    Ian Grant's Avatar
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    Quote Originally Posted by kuad View Post
    so using like an f8 would remedy any possible mis-alignment?
    It might bring the image into sharp focus, but it won't remedy distortion from the mis-alignment, and what happens when you can't stop dow ?


    Some professional enlargers have adjustable fittings to align the based board. These need to be set up properly particularly if they've been moved etc.

    Few enlargers have any or much adjustment. It's more a case of using a good spirit level to ensure the enlarger head is level front/back as well as sideways.

    This is depedent on how well the column is secured and to what, whether there's flexing or bowing. As Bob Carnie said the top of the column should ideally be brace to a wall or ceiling. De Vere's have adjustable brackets, and I had something made to mount my Durst to a wall rather than the baseboard, and a stabiliser bar to the wall at the top.

    Once the head's level then you set the baseboard with a spirit level as well. That works in practice and a test negative will tell you if its sharp all over.

    Ian

  3. #23

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    Quote Originally Posted by tkamiya View Post
    Exactly.... hence my original question of what is "good enough?" I just discovered, putting a tool on the lens board itself actually causes enough of off center weight that the bubble moves off center by just a little.

    I got it to a point where projected image is square and the image at 20x20 or so is sharp to my unaided eyes. I'm going to stop right here.

    Thanks everybody.
    say you want to make a 12x8 inch print from a 35mm negative. Thats roughly an 8.5 times magnification from the negative. The software I have indicates that the depth of field with 50mm enlarger lens aperture of 5.6 (roughly sharpest) would be 0.08mm. That's depth of field at the negative. You can see from that that negative needs to very flat and the lens must be truly perpendicular because with only a very small error the plane of focus will be tilted outside of the negative plane.
    At the easel things are different. The depth of focus will be 3mm either side of sharpest plane so you have a lot more room for error. But if the neg and lens aren't perfectly aligned, then it will be impossible to get it any sharper in the print. Closing down the enlarger lens will increase depth of field and depth of focus BUT at the expense of introducing diffraction. At F11 depth of field is 4.5mm and depth of focus is 16.5mm either side of plane of sharpest focus BUT the circle of confusion has grown to 0.2mm(required for no diffraction) on the print which means it ain't as sharp as it would have been at f5.6. So if you need to close down because your enlarger isn't aligned properly, then you are going to lose sharpness regardless of having huge depth of field at the easel. (well you might see increased sharpness if your enlarger isn't aligned correctly but not as sharp as it could be.)
    So it comes down to whether you want the sharpest possible or whether your viewing criteria accept less than optimum which brings us to your original question. What is good enough? The answer is get it as close as possible to perfectly aligned, especially neg to lens stage. Yes it's difficult to do but its worth it.

    And the bigger your enlargement the narrower the depth of field at the negative plane. i.e. for big enlargements it's even more critical to get alignment correct.
    Last edited by tlitody; 07-21-2010 at 09:59 AM. Click to view previous post history. Reason: typo

  4. #24
    ruilourosa's Avatar
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    i have two laborator´s 1000 and some meoptas and another durst, i align the best i can, but they stay aligned for a long time, i just recheck when i bump into them or after cleaning the lab, i never had problems. But in my university there were some enlargers very resilient to go on alignment, some meoptas, some beselers, but that was perfectly visible on prints.
    vive la resistance!

  5. #25
    Ian Grant's Avatar
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    Quote Originally Posted by ruilourosa View Post
    i have two laborator´s 1000 and some meoptas and another durst, i align the best i can, but they stay aligned for a long time, i just recheck when i bump into them or after cleaning the lab, i never had problems. But in my university there were some enlargers very resilient to go on alignment, some meoptas, some beselers, but that was perfectly visible on prints.
    Sometimes base boards warp, others are made of covered chipboard, and if knocked go off alignment as the fittings move into the board slightly on one side or the other.

    Ian

  6. #26
    ruilourosa's Avatar
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    yes that´s true, it may fall out of alignment but honestly, to fix that just cut a new baseboard made out of something that does not warp maybe marine laminated wood, or so, and screw it tight...
    vive la resistance!

  7. #27
    MattKing's Avatar
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    Quote Originally Posted by kuad View Post
    so using like an f8 would remedy any possible mis-alignment?
    Nope.

    It helps with some types of alignment problems (e.g. lens and negative carrier not parallel) but not with others (e.g. centre of lens and centre of negative carrier don't line up).
    Matt

    “Photography is a complex and fluid medium, and its many factors are not applied in simple sequence. Rather, the process may be likened to the art of the juggler in keeping many balls in the air at one time!”

    Ansel Adams, from the introduction to The Negative - The New Ansel Adams Photography Series / Book 2

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