Switch to English Language Passer en langue française Omschakelen naar Nederlandse Taal Wechseln Sie zu deutschen Sprache Passa alla lingua italiana
Members: 69,750   Posts: 1,515,786   Online: 989
      
Page 2 of 3 FirstFirst 123 LastLast
Results 11 to 20 of 22
  1. #11
    MattKing's Avatar
    Join Date
    Apr 2005
    Location
    Delta, British Columbia, Canada
    Shooter
    Multi Format
    Posts
    12,011
    Images
    60
    The condensers are lenses.

    As such, they will focus the light over different areas, depending on the distances between the condensers, the light source, and the negative stage.

    I would guess that the focal lengths for the condenser lenses are close to the distances involved, so moving them results in large swings.
    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

  2. #12

    Join Date
    Feb 2009
    Shooter
    Large Format
    Posts
    654
    A pair of condenser lenses works in unison to concentrate the light into a converging conical projection of fixed angle.

    We raise or lower the condenser set so that the light is concentrated into an evenly-illuminated circle that is only slightly larger than the diagonal of the opening in the negative carrier.

    In this way we get the brightest evenly-illuminated projection at the print. The Beseler 23C and 45M condenser enlargers have a convenient upper bellows to allow easy focusing of the circle of illumination by turning an elevation knob to continuously vary the condenser distance above the negative to suit the format.

  3. #13
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,411
    Images
    2
    So the condenser makes a "V" shape, that is, the light exiting the lowest condesner lens is at maximum diameter and converges beyond that point?

    I'll have to experiment some more it sounds like.
    If you are the big tree, we are the small axe

  4. #14

    Join Date
    May 2003
    Location
    Valley Stream, NY
    Shooter
    Multi Format
    Posts
    3,216
    Quote Originally Posted by Ian C View Post
    A pair of condenser lenses works in unison to concentrate the light into a converging conical projection of fixed angle.

    We raise or lower the condenser set so that the light is concentrated into an evenly-illuminated circle that is only slightly larger than the diagonal of the opening in the negative carrier.

    In this way we get the brightest evenly-illuminated projection at the print. The Beseler 23C and 45M condenser enlargers have a convenient upper bellows to allow easy focusing of the circle of illumination by turning an elevation knob to continuously vary the condenser distance above the negative to suit the format.
    That is exactly correct. If you were to set the upper bellows to the largest size negative, that is fully compressed, you will get even illumination for a 35mm or larger negative. However, the image cast onto the baseboard will not be as bright as if you had set it to match the film format you are using. With a diffused type light source, be it a cold light like the Aristo units or a dichro color head, the light source should always be placed as closely as possible to the negative carrier.
    Frank Schifano

  5. #15
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,411
    Images
    2
    Ok this makes sense, but I still don't understand what I saw with my 6x6 carrier. I suppose it could've been my lens' fault; though it was a 75mm, so IDK.

    Thanks guys and gals

  6. #16
    David Brown's Avatar
    Join Date
    Feb 2004
    Location
    near Dallas, TX USA
    Shooter
    Medium Format
    Posts
    3,256
    Images
    5
    From the actual manual:

    The condenser assembly, which can be used with other illumination systems, houses the heat absorbing glass and the lenses which focus the light rays to produce Beseler's exdusive "Cone-of-Light" illumination. Also incorporated in this assembly is the color filter cornpartment and its filter holder, designed to hold 6" color printing filters, variable contrast or neutral density filters.

    The position of the negative stage relative to the condenser lenses is important when using the condenser lamphouse. The negative size indicator and negative stage lock can help you position and hold in place the setting to match your negative.

    There should be an indicator on the right rear of the head, although it is missing on many machines (it's missing on mine.)

    You can easily make one from thin metal, plastic, wood, even cardboard. Here are the indicator mark measurements for the different size negatives, all from the LOWER of the two screw holes:

    4 x 5--one inch up
    3 /14 x 4 1/4--2 3/16" up
    2 1/4 x 3 1/4--3 1/4 " up
    2 1/4 x 2 1/4--4 1/4" up
    35mm--5 3/4" up.

    Keep in mind that the precision required here is not very great. Actually, you can enlarge all the smaller sized negatives with the head set at 4 x 5, although that doesn't make greatest use of the enlarger's light intensity. If in doubt, just fudge a bit on the side of a bigger negative.
    David
    Taking pictures is easy. Making photographs is hard.

    http://www.behance.net/silverdarkroom
    http://silverdarkroom.wordpress.com

  7. #17
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,411
    Images
    2
    Thanks David, that's great info. I'm pretty positive I don't have said indicator, but I'll look. Though, I definitely understand the basic concept now.

  8. #18

    Join Date
    Mar 2004
    Location
    San Francisco Bay Area
    Shooter
    Multi Format
    Posts
    822
    Images
    41
    The indicator screws into the right side rear at the base of the upper bellows. Since it has to be removed to fit large colour heads like the 45S, they are often missing. You can see one here http://grahampatterson.home.comcast....g/beseler2.jpg and this shows why it is often missing: http://grahampatterson.home.comcast....g/DSCN0740.jpg.
    I feel, therefore I photograph.

  9. #19
    holmburgers's Avatar
    Join Date
    Aug 2009
    Location
    Rochester NY (native KS)
    Shooter
    Multi Format
    Posts
    4,411
    Images
    2
    Thanks Graham; indeed, last night I looked at it and saw evidence of "what used to be"!

    One more question has creeped up... what does the filter holder for between the condensers look like? I've got the opening, but no holder. It's not a big deal, I'm going to take 6" Ilford filters, cut out the required curve and make a holder out of matboard, but to get an idea of the holder would be helpful. I'll do some searching, but if someone knows of a link....
    If you are the big tree, we are the small axe

  10. #20

    Join Date
    Feb 2009
    Shooter
    Large Format
    Posts
    654
    The filter drawer is thin sheet aluminum that has been formed to hold the filter. Both the 23C and 45M enlargers are similar in this respect.

    Part #18 here. You’ll have to increase the magnification to see it properly.

    http://www.beselerphoto.com/img/exploded.45mxt.body.gif

Page 2 of 3 FirstFirst 123 LastLast


 

APUG PARTNERS EQUALLY FUNDING OUR COMMUNITY:



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