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Thread: 20х24" enlarger

  1. #1
    mamanton's Avatar
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    20х24" enlarger

    Hello! Let me make the announcement!
    We are going to construct a big enlarger, together with Mr. Kienzle and Mr. Heiland.
    Our plans:
    - 20x24'' (50x60cm) LED cold light source split grade system. We already use those systems in Horizontal 8x10'' De Vere and Vertical 8x10'' Kienzle enlargers. And we are completely satisfied.
    - Horizontal self-tuning enlarger. The main idea is not to use the rails as usual, but put the enlarger approximately perpendicular to the wall, then it will align the plane using lasers by itself.
    - Lenses is a big question! We want to provide the distance for the bellows about 1 meter, but I still don't know which exactly lenses we'll use for 11x14, 12x16, 12x20, 16x20 and 20x24''.
    - Negative carrier is the next big question. Conventional frame with glasses would be so heavy that the enlarger will be able to roll over on its side when the printer will pull it out from the enlarger )) So what we're trying to come up with a new system without glasses.

    to be continued...

  2. #2
    bob carnie's Avatar
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    Re: 20х24" enlarger

    looking forward to your progress

  3. #3
    Drew Wiley
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    Re: 20х24" enlarger

    Without a glass carrier ? How do you expect to achieve any focus accuracy worthy of negatives this big in the first place? Same goes for wide-angle enlarging lenses. Other than the LED light source itself, why try to re-invent the wheel? Big horizontal process cameras could easily be retrofitted for this kind of application.
    I once threw out something like that, superbly made, just to cannibalize the suite of Apo Nikkor lenses.

  4. #4
    ic-racer's Avatar
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    Re: 20х24" enlarger

    Of course the bigger the negative and the longer the lens, the greater error allowed in field flatness. One thing of potential concern is heat. Perhaps Drew has the same thing, but on the CLS2000 Durst head, a separate blower, as strong as a hair blower, is dedicated to just blow on the negative carrier to keep the negative and glass cool.

  5. #5
    Drew Wiley
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    Re: 20х24" enlarger

    Garsh, I once had a Durst color mural head that needed a dedicated 240V breaker just for the damn cooling fan. It drew more wattage than a commerical table saw. That's when I decided to design my own colorhead, at least for big Cibachromes. Modern RA4 prints require just a fraction of that amount of halogen nuking. I've been down quite a bit of this route myself and can certainly sympathize with what they have in mind, but also know the inherent shortcomings. Sure, you could mount distance-measuring lasers on the machine and correct the plane of your target easel within a millimeter each corner. But an aligned track is way easier and cost effective. And my definition of suitable lasers is probably a lot fancier than theirs. I used both lasers and special optics to calibrate my machine; but I have better access to that stuff than most, at least in terms of borrowing it when necessary.

  6. #6
    mamanton's Avatar
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    Re: 20х24" enlarger

    Quote Originally Posted by Drew Wiley View Post
    Without a glass carrier ? How do you expect to achieve any focus accuracy worthy of negatives this big in the first place?
    there are two main ideas - magnetic frame, and the frame which pulls the negative in all directions. We'll see...

  7. #7
    mamanton's Avatar
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    Re: 20х24" enlarger

    Quote Originally Posted by ic-racer View Post
    One thing of potential concern is heat. Perhaps Drew has the same thing, but on the CLS2000 Durst head, a separate blower, as strong as a hair blower, is dedicated to just blow on the negative carrier to keep the negative and glass cool.
    The 8x10'' LED enlargers has no cooling system, as they are very poorly heated. But first rough estimates of the heating of the LEDs on 20х24'' will correspond to approximately 1 kilowatt lamp - like Durst 5x7'' enlarger with CLS1000 head. So, cooling is likely to have to do with silent fans.

  8. #8
    mamanton's Avatar
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    Re: 20х24" enlarger

    Quote Originally Posted by Drew Wiley View Post
    Sure, you could mount distance-measuring lasers on the machine and correct the plane of your target easel within a millimeter each corner. But an aligned track is way easier and cost effective.
    On regular wheels with lasers enlarger can be transportable as needed )) And we found that to make the rails perfectly flat on a distance of three meters was not an easy task, besides, we hid them in the floor level.

  9. #9

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    Re: 20х24" enlarger

    It looks to be a funny project. Go ahead!

    Well... I`m into some existential and metaphysical doubt because I`m shooting and enlarging 5x7"... many times I wonder if it is really worth it when compared to 4x5"... 4x5" is minimal in comparison, with their lightweight cameras and small enlargers... so, a 20x24" enlarger?!?!?

    I know, it`s mostly for fun. For sure most of us actually shoot LF just for that large amount of fun!
    -----
    BTW, most of my LF negatives (up to 8x10") are perfectly flat after the processing. So if 20x24" lies with the same flatness, if heat is not of an issue a vertical glassless carrier seem reasonable... maybe a large clip on top (magnetic) and a "guided", slightly loaded large clip at the bottom will work... just thinking aloud.

    What about the working aperture? If my Componon S 180mm ask for f16 to have a barely flat field, which aperture an 600 (800?) mm lens would need?

  10. #10

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    Re: 20х24" enlarger

    Hello, Mamanton,

    this all sounds really great!

    ""Lenses is a big question! I still don't know which exactly lenses we'll use for 11x14, 12x16, 12x20, 16x20 and 20x24''".

    I was really surprised, how this question could be asked from optical specialists like Mr. Heiland and Mr. Kienzle.
    So today, I had to ask Mr. Heiland himself, and I became calm again - every thing seems to be clear to him, like everytime :-)

    Ritchie

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