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  1. #1
    cliveh's Avatar
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    Point source enlarger

    Can someone enlighten me here? Is there a difference between a point source enlarger and a condenser enlarger? Or is the term point source enlarger another name for a condenser?

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

  2. #2
    MattKing's Avatar
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    A point source enlarger is a relatively rare beast. I have never actually used one.

    Most enlargers that we see described as condenser enlargers are actually a compromise. They combine condensers to focus and collimate the light with a semi-diffused light source, such as a frosted bulb.

    A point source enlarger replaces the frosted bulb with a point light source. The condensers need to be carefully matched to the source, and everything needs to be accurately positioned.

    The result: excellent accutance, and maximized dust in your prints!
    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

  3. #3
    ic-racer's Avatar
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    In technical terms it can be reduced to the presence or absence of a frosted globe between the filament and condenser. Back in the heyday the point source was excellent for enlarging electron micrographs. Today some have posted on these forums they use point source enlargers for their expressive printing.
    Last edited by ic-racer; 08-21-2014 at 04:23 PM. Click to view previous post history.

  4. #4

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    http://www.durst-pro-usa.com/world_images/theofcon.htm

    "Most condenser systems are designed to work at a certain given f-stop when using a point light lamp. Most often this f-stop will be f11. When using an opal lamp you are free to use any f-stop on the lens:"

    http://www.durst-pro-usa.com/world_i...s/image005.jpg

  5. #5
    cliveh's Avatar
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    Quote Originally Posted by MattKing View Post
    A point source enlarger is a relatively rare beast. I have never actually used one.
    Do any APUG members use one? If so what do you think about this method?

    “The contemplation of things as they are, without error or confusion, without substitution or imposture, is in itself a nobler thing than a whole harvest of invention”

    Francis Bacon

  6. #6
    KenS's Avatar
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    Point-source enlargers exposures are used by controlling the timing of the exposure while adjusting voltage to the lamp... with the lens ALWAYS used wide open. They also require special 'coatings' on the condensers. Their use is usually the most common for either 'extreme' enlargement of transmission electron micrographs.... scanning electron micrograph negatives are were usually printed using the 'standard' opal lamp.
    A secondary benefit can be obtained by the point-source enlarger is (was?) for making LOW magnification B/W negatives from stained and sectioned tissue slides in order to get the fine detail often difficult to 'acquire' at lower magnification... with even the best of 'standard' microscopes. I have to imagine that 'digital' sensors have now 'replaced' the silver-gelatin negative in electron microscopy.

    In my last job position, I spent many a happy (or frustrating) hour standing in front of a Durst 138S... over some 20 years) .

    Ken
    Quando omni flunkus moritati (R. Green)

  7. #7
    David A. Goldfarb's Avatar
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    There was a fair amount of discussion of this topic around 2005-7 on APUG, so try the search engine to find lots of information in the archive. Here's one of the more detailed threads:

    http://www.apug.org/forums/forum43/2...plication.html
    flickr--http://www.flickr.com/photos/davidagoldfarb/
    Photography (not as up to date as the flickr site)--http://www.davidagoldfarb.com/photo
    Academic (Slavic and Comparative Literature)--http://www.davidagoldfarb.com

  8. #8
    RalphLambrecht's Avatar
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    Quote Originally Posted by MattKing View Post
    A point source enlarger is a relatively rare beast. I have never actually used one.

    Most enlargers that we see described as condenser enlargers are actually a compromise. They combine condensers to focus and collimate the light with a semi-diffused light source, such as a frosted bulb.

    A point source enlarger replaces the frosted bulb with a point light source. The condensers need to be carefully matched to the source, and everything needs to be accurately positioned.

    The result: excellent accutance, and maximized dust in your prints!
    ExactlyIf I were you I'd stay away from themunless you have a specialized need.I recommend an enlarger were the light source can be changedsuch as the Durst L1200.point source enlagers need experience to be tamedand even then print very harsh.so,be prepared to develop very soft negatives.
    Regards

    Ralph W. Lambrecht
    www.darkroomagic.comrorrlambrec@ymail.com[/URL]
    www.waybeyondmonochrome.com

  9. #9

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    I used to have a point source head to fit on a DeVere 504 condenser head by replacing the top of the head. I didn't use it too much, (before giving it away) as found it quite difficult to work with. As I remember, the condenser lenses have to be aligned exactly and the lamp must be in exactly the right position. I think the enlarger lens could only be used at a certain f stop as otherwise would vignette. It certainly gave more contrast and the sharpest grain ever, but the amount of dust and scratches it found made spotting more of a chore. And normally I enjoy spotting! Couldn't even use anti newton glass in the carrier as the texture would show. Was used now and again 20 years ago for lith printing with even more crunch, but would image we would have then sent the prints out for retouching! Personally, I wouldn't be rushing to use one again!

  10. #10
    Ian Grant's Avatar
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    I made a point source head back in the mid 1970's for a De Vere 54a which I used horizontally, the head was quite long. Like Mike says it was very finicky I had to check the alignment of the light source and adjust depending on the degree of enlargement.

    I used it to get maximum contrast and also get the best light output for large prints to keep exposure times under a couple of minutes with the lens stooped down to f11/f16. When I close the company I scrapped the head and enlarger.

    Ian

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