Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 74,136   Posts: 1,637,392   Online: 924
      
Page 2 of 2 FirstFirst 12
Results 11 to 16 of 16
  1. #11

    Join Date
    Feb 2007
    Location
    Slovenia
    Shooter
    Multi Format
    Posts
    943
    Images
    9
    The author of the following paper advocates the use of a point light source system: http://www.durst-pro-usa.com/pdf/COL...ED%20LIGHT.pdf

    His argument is that a minimally exposed and developed film is to be preferred for maximum resolution and best tonality. (start with page 36)

  2. #12

    Join Date
    Jul 2011
    Shooter
    8x10 Format
    Posts
    3,305
    Point light sources are pretty arcane, and I don't see why anyone would even need one. But if you love spotting prints... Otherwise, the best
    way to get great tonality along with great resolution is to shoot a larger sized film to begin with, and otherwise have all you darkroom gear
    precisely aligned. The link provided above probably wants to sell you something for tens of thousands of dollars with a mandatory service contract. Don't ask me how I happen to know that.

  3. #13
    cliveh's Avatar
    Join Date
    Oct 2010
    Shooter
    35mm RF
    Posts
    3,993
    Images
    345
    Am I correct in assuming that a point source enlarger would be more suited to a smaller format size?

    “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

  4. #14
    richard ide's Avatar
    Join Date
    Nov 2005
    Location
    Wellington County, Ontario
    Shooter
    Multi Format
    Posts
    1,227
    Point source enlargers were ideal for document reproduction (maps, engineering drawings etc). I have the head of a camera enlarger for 8 x 10 negatives. You could make a print from a negative with a Dmax of .30 and the print would be black lines on a white background. The largest condenser enlarger I came in contact with could enlarge a 21" x 27" image. Distance from lamp to condenser is very critical but easy to set up. Image sharpness is not a problem. As said before, every bit of dust shows.
    Richard

    Why are there no speaker jacks on a stereo camera?

  5. #15
    ic-racer's Avatar
    Join Date
    Feb 2007
    Location
    Midwest USA
    Shooter
    Multi Format
    Posts
    6,607
    Quote Originally Posted by cliveh View Post
    Am I correct in assuming that a point source enlarger would be more suited to a smaller format size?
    Back in the day electron micrographs were frequently made on sheet film a little smaller than contemporary 4x5" film. That film size is small to some, and large to others

  6. #16
    KenS's Avatar
    Join Date
    Jan 2005
    Shooter
    Multi Format
    Posts
    362
    I was just re-reading these posts and just realised that some time ago I had written in an MS Word' to allow me to edit/correct before posting and was interrupted... I 'put it away' and somehow for got to finish what I had 'started'.

    One of the 'other' advantages of the point source enlarger was making 'low' ie 4 to ~20x magnification negatives directly from sectioned and stained tissue samples rather than making the required negatives under the microscope lenses... especially if the sections in question were cut with an ultra-microtome.
    The glass microscope slide is 'inverted' (ie. coverslip 'down') when placed in the negative carrier and 'projected' onto sheet film in a film holder that is 'adjusted' such that the plane of the film is parallel to the plane of the microscope slide.

    This technique was the subject of a paper published in the Journal of Biological Photography some years ago and having used the technique myself, I can confirm the advantages. if anyone is interested, I'll see if I can find my copy and forward or post the issue/date/author.

    Ken

    Ken
    There are holes in the sky where the rain gets in,
    But they're ever so small that's why rain is thin.
    Spike Milligan.

Page 2 of 2 FirstFirst 12


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



Contact Us  |  Support Us!  |  Advertise  |  Site Terms  |  Archive  —   Search  |  Mobile Device Access  |  RSS  |  Facebook  |  Linkedin